Vocab

Section 1: Cells and the Anatomy of the Brain

Neuron - The primary nerve cells cannot be easily made as old ones die off; however, new connections between these neurons continue to change over a person’s lifetime.

Soma - The cell body of the neuron. It has all of the essential parts of the neuron, like the Nucleus, Golgi Apparatus, and Endoplasmic Reticulum.

Neuronal Membrane - The membrane that separates the inside of the cell from the outside; it is filled with cytosol.

Dendrite - This structure receives Signals from other Neurons and brings the input to the cell. The name comes from the Greek word “treelike,” and the system may branch many times.

Axon - This structure is the “wire” transmitting output signals from the cell.

Myelin - This is a fatty substance that is formed by glial cells which insulate the axon.

Nodes of Ranvier - These are the gaps in the myelin on the axons, which are used to access the fields outside the cells.

Axon Hillock - This is the part of the neuron where the axon begins.

Axon Terminal - This is the part of the neuron where the axon ends.

Synapse - This is where one neuron connects to another neuron.

Presynaptic Neuron - This is the first neuron in a synapse.

Postsynaptic Neuron - This is the second neuron in a synapse.

Synaptic Cleft - This is the space between the neurons that neurotransmitters must pass through to reach the postsynaptic neuron.

Vesicles - These are the spherical packets that are in the axon terminal and are filled with neurotransmitters.

Neurotransmitters - Signaling Chemicals in the Nervous System.

Morphology - How the shape of a neuron dictates what job it should do.

Dendritic Arbor - This is the location of the branching dendrites on a neuron.

Interneurons - These neurons connect other neurons within the nervous system and are pretty small, without long axons or large dendritic arbors.

Grey Matter - This type of matter comprises cell bodies and dendritic arbors of neurons.

White Matter - This type of matter comprises myelinated axons of the neurons.

Glia - These are the nonneuronal cells of the Nervous System.

Oligodendrocytes - These cells myelinate axons in the Central Nervous System.

Schwann Cells - These cells myelinate axons in the Peripheral Nervous System.

Astrocytes - This is the most common type of glial cell, and it regulates the chemical makeup of the extracellular fluid in the space between the cells in the nervous system by removing excess signaling ions and maintaining proper balance, along with other functions.

Blood Brain Barrier - This is the barrier between things in the bloodstream and the brain and keeps infections away from the neurons.

Microglia - These cells are smaller than other glia. However, they are critical for neuron health because they help to protect against pathogens. This is important because the brain is isolated from the rest of the body.

Central Nervous System - This consists of the parts of the nervous system encased in bone, specifically the brain and spinal cord.

Meninges - The three layers that surround and protect the Central Nervous System.

Dura Mater - Latin for “tough mother” is the meninges' outermost part.

Epidural Space - This space outside the Dura Mater comprises fats for shock absorption and can be used to inject medication.

Arachnoid Membrane - The middle part of the Meninges features long stringy components.

Subdural Space - If brain trauma occurs, blood may pool here.

Subarachnoid Space is much larger than the Arachnoid Membrane and is filled with Cerebrospinal Fluid, which cushions the brain.

Pia Mater - Latin for “Gentle Mother,” this structure is fragile and follows the brain's contours and allows blood vessels to pass through.

Cerebral Hemispheres - This term refers to the left and right sides of the brain.

Gyri - These are the bumps on the brain.

Sulci - These are the grooves on the brain.

Cerebral Cortex - This refers to the outermost layer of the Cerebrum.

Frontal Lobe - The brain region responsible for thinking, decision-making, emotion, attention, and other cognitive functions.

Motor Cortex - This is located towards the back of the Frontal lobe and is responsible for the movement of muscles.

Prefrontal Cortex - This is the Frontal Lobe region in front of the motor cortex.

Parietal Lobe - The brain region responsible for a sense of touch, temperature, pain, body position, and spatial relationships.

Occipital Lobe - The brain at the back of the Cerebrum processes information from the eyes.

Temporal Lobe - The brain region near the ears responsible for audio processing, music, memory, and object recognition.

Cerebellum - Another structure that sits behind the Cerebrum and has the Latin name for “little brain.” This region is responsible for the motor system and making smooth and coordinated movements, like riding a bike. It has over 50% of all of the neurons in the brain.

Subcortical Structures - Brain regions below the cerebral cortex are in the left and right hemispheres.

Amygdala - This brain region is found in the temporal lobe, and its name in Greek means “Almond.” It is a significant component of the limbic system. It processes threat, stress, reward, and arousal.

Limbic System - One of the systems of the body that regulates emotions.

Hippocampus - This brain region is crucial for long-term memory and spatial navigation and is also considered a part of the limbic system. Its name is from a mythological version of a sea horse, with a horse's upper body and a fish's lower body.

Memory Consolidation - This is the process of transferring short-term memories to long-term memories and creating new ones.

Thalamus - This brain region is in the center of the cerebral hemisphere and acts as the relay station between the body and the brain. Nearly all inputs from your body go through this part of the brain, except for some notable exceptions, like smell.

Hypothalamus - This organ mediates the pituitary gland and many unconscious functions of the body. It is also neighbors with the pituitary gland.

Pituitary Gland - This gland is known for releasing many essential growth hormones. It is neighbors with the hypothalamus.

Hormones - These are the chemical messengers of the body.

Basal Ganglia - These are a cluster of nuclei found in the center of the cerebral hemisphere around the thalamus. This region of the brain is responsible for controlled movements.

Caudate Nucleus, Putamen, Globus pallidus, Subthalamic Nucleus, and Substantia Nigra - These are parts of the Basal Ganglia.

Brainstem - This part of the brain at the bottom is responsible for breathing, heart rate, coordination, and reflexes.

Midbrain - This is the topmost part of the brainstem, and it regulates eye movement and the pupillary light reflex, which constricts your eye when there is bright light. It also connects to the auditory information to create an environmental map.

Pons - This is the middle part of the brainstem, and it contains regions to integrate visual and audio information, coordinating facial movements, chewing muscles, hearing, and balance. The name comes from the Latin word meaning bridge.

Medulla - This is the lowest part of the brainstem, and it is responsible for touch sensations from the face, swallowing food, vomiting, regulating heart rate, blood pressure, breathing, and other functions.

Spinal Cord - This is the other major part of the Central Nervous System other than the brain.

Vertebrae - This is what the spinal cord is encased in.

Reflexes - This is what the cell bodies in the spine are responsible for.

Cervical Spinal Cord - This is the top part of the spinal cord. (Head, Neck, Shoulders)

Thoracic Spinal Cord - This is the middle part of the spinal cord. (Chest and Torso)

Lumbar Spinal Cord - This is the lower part of the spinal cord. (Hips and Front of the Legs)

Lumbar Spinal Cord - This is the bottom part of the spinal cord. (Buttock, Back of the Legs, Genitalia)

Ventricular System - This is a series of open holes inside the Central Nervous System filled with Cerebrospinal Fluid.

Lateral Ventricle - Each Cerebral Hemisphere contains this element of the Ventricular System.

Third Ventricle - This is where the Lateral Ventricle is connected to the left and right Thalamus

Cerebral Aqueduct - This is what the Ventricular System narrows into.

Fourth Ventricle - This is what the Cerebral Aqueduct widens into.

Central Canal - The CSF can be found here in the Spinal Cord.

Choroid Plexus - This material lines the ventricles and creates new CSF.

Nervous System - This part of the Peripheral Nervous System comprises all axons leaving and entering the spinal cord that bring information to and from the body's tissues. This part of the Nervous System controls voluntary actions.

Autonomic Nervous System - This part of the Parasympathetic Nervous System controls involuntary actions. The name for this part of the Nervous System also comes from the Greek Word “autonomia,” meaning independence.

Sympathetic Nervous System - This part of the Nervous System is responsible for your body's “fight or flight” response.

Sympathetic Chain - This is a specialized set of Ganglia that runs alongside the spinal cord.

Parasympathetic Nervous System - This part of the Nervous System inhibits stress and is responsible for the rest and digestion functions. The neurons that allow this area to function are in the brainstem and the sacral spinal cord.

Section 2: Neural Communication

Ions - These are atoms that have a positive or negative charge.

Membrane Potentials - This is a way to describe the electrical charge that a cell has compared to the electrical charge elsewhere. This is measured in millivolts(mV).

Resting Membrane Potential - This is when a neuron or other cell

that can send electrical signals is not doing so.

Cytosol - This is the fluid inside of the cell.

Extracellular Fluid - This is the fluid outside of the cell.

Channel - This is an opening where ions can pass through the neuronal membrane.

Permeability - This is the ability of a particular ion to pass from one side to another of the neuronal membrane.

Passive Transport - This is when an ion moves from one area to another due to a natural force and requires no energy expenditure.

Ionic Concentration - This is the number of ions in a particular volume of water forming a solution (such as the cytosol or the extracellular fluid)

Diffusion - This is the process of an ion moving from an area of high concentration to an area of lower concentration.

Concentration Gradient - This measures how the concentration of something changes from one place to another.

Electrical Potential - This is another term for electric charge.

Ion Channels - These are proteins that form specialized openings in the neuronal membrane through while ions can pass through.

Gating - This is the process of triggering an ion channel to open or close.

Voltage-gated Ion Channels - This type of ion channel opens and closes when the membrane potential is at a particular voltage.

Ligand Gated Channels - This type of channel opens when a particular molecule binds to a specific location on the track.

Conformation - This occurs when a molecule triggers a change in shape, which can open a channel and allow ions to flow through.

Active Transport - This is when an ion is actively moved or forced to go against either the concentration gradient, the electrical potential, or both. This type of transport also requires energy produced by the cell.

Sodium-Potassium Pump - This is a crucial pump in neurons for establishing the resting membrane potential. This pump breaks down ATP and conforms in its phosphorylated state, binding three sodium ions from the cytosol and releasing any bound potassium ions and in its phosphorylated state, binding two potassium ions and from the extracellular fluid and releasing any bound sodium ions.

-60 to -80mV - This is the resting electrical potential of most neurons.

Potassium Leak Channels - These channels are always open and are not gated in any way. They slowly leak potassium ions out of the cell.

Electrical Driving Force - This is the force that occurs when the electrical potential across the cell membrane becomes so large that the potassium ions on one side will start to repel each other and force some ions back into the cell. This force is proportional to the difference inside and outside the cell.

Chemical Driving Force - This is the force that drives Potassium ions out of the cell and counteracts the electrical driving force. This force is proportional to the difference inside and outside the cell.

Equilibrium - When the Electrical and Chemical Driving Forces are equal, the cell is in this state.

Equilibrium Potential - This is the membrane potential that the cell is at when a certain ion reaches equilibrium.

The Nernst Equation - This is the equation that is used to mathematically calculate the equilibrium potential for a certain ion. (E-(kt/ze) * ln(Red/Ox))

Goldman Equation - This equation is similar to the Nernst Equation but takes into account that many different ion channels are open at the same time and takes that into account. The equation is really long and annoying.

Action Potential - This is the electrical potential across the neuronal membrane when the cell is active and firing. It only lasts a few milliseconds.

Rising Phase - This is the first phase of the action potential. During this phase, the membrane potential becomes more and more positive due to an influx of positive ions. This is also called depolarization.

Overshoot - This is the part of the action potential where the membrane potential becomes positive (+30-40 mV) instead of negative.

Falling Phase - This is where the membrane potential becomes more and more negative due to positive ions leaving the cell. It has many names, such as hyperpolarization or repolarization.

Afterhyperpolarization - This is when the cell becomes more negative than the resting potential(-80 mV) and is near the end of the action potential.

Stimuli - These are things that can trigger the action potential.

Threshold - This is the point where the action potential is triggered; anything lower than the trigger does not activate the action potential. (-60 and -50 mV)

All or None Principle - This principle states that the action potential will either fully trigger or not trigger at all.

Absolute Refractory Period - This is when an action period cannot be activated after a previous one is still firing. This is because the voltage-gated channel is still opening.

Effluxes - This is when something flows out of the cell.

Delayed Rectifier - This is meant to describe the slow-acting voltage-gated potassium channel and how lets the concentration get a bit too low before returning to the resting potential.

Relative Refractory Period - This is the period where it is more difficult to active an action potential, as it it during the undershoot.

Propagation - This is the process of moving the action potential down the axon.

Saltatory Conduction - This is the conduction down a myelinated axon, as the message skips down the inside of the axon, bouncing on the Nodes of Ranvier, and finally reaches the axon terminal.

Synaptic Transmission - This is the transfer of a signal from one neuron to another through the synapse.

Mitochondria - This is contained in the axon terminal of the presynaptic cell to help produce ATP that powers synaptic transmission.

Microtubules - These are contained in the axon terminal and are long cytoskeletal elements. They do not exist where the axon terminal begins.

Electrical Synapses - These are synapses where the pre and postsynaptic cells are located close enough to have a single set of channels or gap junctions that physically connect them and their neuronal membranes. However, while this type of transfer is fast, the original message cannot be changed.

Voltage-Gated Calcium Channels - These channels are important in the transfer of electrical messages into chemical cones. When the action potential propagates down the axon and reaches the terminal, the voltage-gated calcium channels open. When they open, calcium ions rapidly enter the cell.

SNARE Proteins - These membrane-bound proteins capture vesicles of neurotransmitters that are facing the synaptic cleft.

Synaptotagmin - This is a SNARE Protein that binds with calcium so that the protein is conformed and the two membranes merge, letting the neurotransmitter move out of the vesicle.

Exocytosis - This is the process of releasing chemical neurotransmitters from the presynaptic cell.

Endocytosis - This is the process of recovering a versicle separating back out of the neuronal membrane.

Reuptake Transporter Proteins - This is one way that neurotransmitters are moved out of the synaptic cleft, where proteins move neurotransmitters back into the presynaptic cell. There are other methods of doing what these proteins do, like uptake by glial cells, enzymatic degradation, or letting the neurotransmitter diffuse away over time.

Postsynaptic Density - This is the area of the postsynaptic membrane that is thickly clustered with receptors and their attached molecular machinery.

Ionotropic Receptors - This is a type of ligand gated ion channel receptor. These are membrane-spanning proteins that have a central pore to allow ions to pass.

Excitatory - This is a type of impact that makes it easier to create an action potential.

Excitatory Postsynaptic Potential - This is the brief and transient depolarization that might result from positive ions flowing through ionotropic receptors.

Inhibitory Postsynaptic Potential - This is the brief and transient depolarization that might result from negative ions flowing through ionotropic receptors.

G-Protein Coupled Receptors - This is a type of ligand gated ion channel receptor. They are also known as metabotropic receptors.

Synaptic Integration - This is when all of the EPSPs and IPSPs and are added together.

Spatial Summation - This is when there is lots of synaptic summation over different areas.

Temporal Summation - This is the instance where multiple EPSPs or IPSPs occur in rapid succession at the same synapse and are summed over time.

Metabotropic Receptors - These are another type of receptors other than the ionotropic receptors. They are slower but allow for more complex signals. They are activated in a series of steps, that starts with the binding of neurotransmitters, like the ionotropic receptors, however they themselve are not ion channels. These receptors activate G Proteins or GCPRS or G protein coupled receptors.

GCPRS - These are a type of protein in the metabotropic receptor that split apart into subunits, each of which activates its own set of signal proteins or effector proteins. These proteins can also affect a cell’s metabolism.

Kinase C (PKC) - This is a part of the activation of metabotropic receptors and phosphorylates many different molecules.

Phosphorylation - This is the process of adding a phosphate group to molecules.

Phospholipase C (PHC) - This is a membrane-bound receptor that the G protein binds to in the kinase C pathway.

Inositol-1,4,5-triphosphate (IP3) - This is a molecule that PHC splits into. It binds to specific ligand-gated receptors, IP3-gated calcium channels embedded in the membranes of the ER, which open and allow internal stores of calcium to flow into the cytosol.

Diacylglycerol (DAG) - This is a molecule that PHC splits into. It stays bound to the membrane and activates PKC.

Signal Cascades - This takes longer to produce an effect than the ionotropic receptors, but there is signal amplification, which activates many different ion receptors.

Second Messenger - This is a concept that a molecule that is created or activated by the effector proteins then goes on to affect other parts of the cell.

Serotonin - This is a neurotransmitter that helps to regulate mood. SSRIs block this specific neurotransmitter.

Selective Reuptake Inhibitors - These are specific drugs that inhibit the function of synapses that release serotonin. This means that there is more time for the molecule to bind and rebind to the cell, making a larger impact on the postsynaptic cell.

Agonist - This is a molecule that can bind and activate a receptor to induce a biological reaction.

Antagonist - This is a molecule that can interfere with a receptor's ability to receive chemicals.

Competitive Agonists - These are receptor agents that compete for the same binding site as the endogenous neurotransmitter. They are only really effective if they are much more concentrated than the endogenous receptor.

Noncompetitive Agonist - This is a type of receptor that binds at a different site than the endogenous neurotransmitter, which alters the conformation of the receptor to decrease or silence the effect.Allosteric Site- This is a site that a noncompetitive agonist binds to and is not the site where the endogenous neurotransmitter is.

L-DOPA - This is a drug that is used to treat Parkinson’s disease, which involves the death of dopamine-producing neurons in the basal ganglia. This drug also acts as a dopamine agonist.

Modulatory - This means that the neurotransmitter’s effect is more complex than just excitatory and inhibitory.

Dopaminergic Neuron - This is a neuron that produces Dopamine.

Glutamine - This is the most common excitatory neuron in the brain. Dysregulation of this type of neuron can lead to seizures and sometimes cell death. The dysregulation of this type of cell can be found in epilepsy patients.

Gamma-Aminobutryic Acid(GABA) - This is the most common inhibitory neuron, whose agonists are known for their calming effect. Too little of this neuron can have a similar effect as too much Glutamine. Both of these molecules work together to form a balance in the brain, with them being the two sides of an on-and-off switch.

Excitotoxicity - This is cell death that results from too much excitation.

Catecholamines - These are a group of modulatory neurons made from the same precursor molecule, tyrosine. These molecules include dopamine, norepinephrine, and epinephrine. Neurons that produce these molecules are found in the parts of the brain responsible for movement, mood, attention, and the function of the internal organs.

Tyrosine - This is the precursor molecule for all of the catecholamines.

Ventral Tegmental Area(VTA) - Dopamine produced here is important for regulating the reward system. Drugs like cocaine and methamphetamine directly affect this system, and addictions can be formed.

Substantia Nigra - This is one area where dopamine is produced and where it is used for regulating voluntary movement.

Parkinson’s disease - In this disease, dopamine-producing cells in this area die off, making it difficult for patients to move their muscles voluntarily.

ADHD, schizophrenia, Parkinson’s - Dopamine Diseases

Norepinephrine - This is produced from dopamine by the conversion of a particular enzyme found in cells that specifically produce this neurotransmitter. These cells are found in a small bundle. These neurons send axons all over the brain to help regulate mood and attention, as well as other functions.

Locus Coeruleus - This is a specific region in the brainstem, and in Latin, it means “blue spot” because it sometimes appears blue.

Epinephrine - This chemical is called adrenaline and can treat many conditions, such as clot formation, restarting the heart, and relieving the airway during an allergic reaction. It also plays a vital role in the right or flight response via stimulation of the parasympathetic nervous system.

Serotonin - This chemical is also called 5-hydroxytryptamine (5-HT), and it is produced by a relatively small number of neurons with cell bodies found in the raphe nuclei of the brainstem. This chemical is used in many places but mostly targets the digestive tract. In the brain, it has many functions, most famously emotions. For this reason, it is a common target of drugs for anxiety and depression. Other drugs that target this system include LSD, MDMA, and psilocybin(Magic Mushrooms).

Acetylcholine - This is the primary neurotransmitter found at the neuromuscular junction. This makes it a target for many drugs, for example, a poisonous nerve gas that targets the muscles of the lungs and heart. However, small doses of this chemical can help to treat heart conditions and other medical problems. Nicotine is also a partial agonist to this chemical.

Section 3: The Sensory and Motor Systems

Somatosensation - This comes from the Greek word “soma,” meaning body. This refers to the senses of touch, temperature, pain, pressure, and vibration.

Vestibular System - This is the body system that provides a sense of balance and position in space.

Proprioception - This is the sense that tells you the position of your body, and your bones, joints, and muscles.

Sensory Transduction - This process of converting light, sound, or pressure sensations on the skin to electrochemical signals is called sensory transduction.

Sensory Receptor - This can be an entire cell or a cell process(dendrite or axon that has developed a particular shape) that detects and transduces a specific stimulus of that sensory system.

Receptive Field - This is where a sensory receptor can detect a stimulus.

Retina - This is where light transduction into an electrochemical signal on the inner surface of the back of the eye occurs. The neurons here are seemingly inside out. The light must pass through the thick fluid.

Pigmented Epithelium - This is a layer in the eye that needs to be outside of the layer of photoreceptor cells to help support their functions. These cells also have many other functions, like absorbing excess light and eliminating old cells.

Choroid - This is just outside of the pigmented epithelial layer of the eye, and it needs to be just outside of these cells to help support their function.

Fovea - This is the very center of the retina, and it is where the vision is the most acute or sharp.

Rods - These tend to have more discs and are more sensitive to low levels of light and peripheral vision. These are located towards the edges of the retina.

Cones - These cells are more useful in high-light settings and are located in the center of the retina. Specific cones can be more receptive to areas of the visible spectrum, like red, blue, and green.

Opsins - This is another word for pigment.

Rhodopsin - This is a pigment that rods have.

Trichromatic - This is a system of vision that primates have, meaning they use only three kinds of cones.

Mantis Shrimp - This animal can see ultraviolet and infrared light.

Phosphodiesterase - This molecule is an enzyme active when the opsin encounters a G protein.

Cyclic Guanosine Monophosphate(Cyclic GMP) - This molecule helps keep special ion channels open. When it is broken down, there is not enough of it to bind to receptors, and therefore, they close.

Photoreceptor Neurons - These are neurons that are meant to sense light.

Cornea - This is the front transparent layer of the eye where much of the refraction occurs. This is also the place that is altered in Lasik.

Iris - This is where the eye is colored. This part of the eye expands and contracts based on the light.

Pupil - This is the small hole where light enters the eye.

Crystalline Lens - This is a many-layered crystalline structure, where light passes through after going through the cornea.

Visual Field - This is the field that you can see.

Farsightedness - This is where the image gets focused behind the retina, and it can be caused by normal aging and the retina getting less flexible.

Myopia - This is another name for near-sightedness, and it is where the eyeball is shaped such that the distance from the cornea to the retina is too long, and the image focus falls in front of the retina. Glasses can be used to fix this problem.

Bipolar Cells - These cells are bonded to when photoreceptor cells are depolarized, and glutamate binds to them.

Retinal Ganglion Cells - These cells synapse with the bipolar cells in the visual system, and the axons of these cells make up the optic nerve at the back of the eye.

Optic Nerve - This is referred to the blind spot of the eye since there are no photoreceptors here.

Amacrine Cells - These cells distribute information from one bipolar cell to many ganglion cells.

Horizontal Cells - These cells form connections between one central rod or cone to many more distant photoreceptors and several bipolar cells, creating lateral inhibition.

Lateral Inhibition - This refers to the capacity of excited neurons to reduce the activity of their neighbors.

Center-Surround Receptive Fields - These are retinal neurons that are depolarized and inhibit surrounding neurons. The purpose of this is to make edges sharper and enhance contrast in images.

Retinofugal Pathway - This term comes from the Latin word meaning fleeing, and it is the path of information from the eye into the Central Nervous System via the optic nerve.

Optic Chiasm - This is the part in the Retinofual Pathway where both eyes come together and is named for the Greek letter chi, which looks like an X.

Decussation - This is the crossing of neurons in the Retinofugal Pathway.

Optic Tract - This is the bundle of neurons after they have crossed with each other.

Binocular Vision - This vision comes from comparing an object from two different places, like the left and right eye, and using that to calculate depth.

Lateral Geniculate Nucleus - This is a place in the brain where the axons of the retinal ganglion synapse with gray matter. This part of the brain is also specialized for processing visual inputs. Specific layers of this structure perform different functions, and the signals from the left and right eye are kept and processed separately. The cells in this area are relatively similar to those that are not in this region. For example, these cells have a center and a surround that inhibit each other to highlight or amplify the edges falling onto the field. The map of the receptive fields in this area is also the same as in the retina, meaning if two points are next in space, they will hit neighboring parts of the retina. Then, they will also be represented by neighboring parts of this area. This area also receives input from other areas other than the eye, and using that, it will decide how to process the visual information.

Primary Visual Cortex or V1 - The neurons of the LGN that leave the thalamus and project to the occipital lobe and synapse there, bringing their action potential signals here. This region is also specialized for doing the initial processing of visual input, and as a result, it is one of the most highly studied regions of the brain. Layer 4 of this region is the most important, but it can have six or more layers.

4C - This is the layer of the V1 that receives most of the input. Spiny stellate neurons are found there. In the other parts of V1, there are many pyramidal cells. This area is also called the striate cortex because of its distinct layers.

Spiny Stellate Neurons - These are cells whose dendrites are covered with spines to maximize the number of synapses that they can have.

Monocular - This means that since the layers of the LGN only have input from one eye, the neurons of the input layers of V1 also only get input from one eye. Once you move past the 4C input, player information from the two eyes starts to mix.

Retinotopic Map - This is the map that is created in the LGN that is meant to represent the visual field. Since all of the visual information from the right eye is processed in the left side of the brain and vice versa, the retinotopic map is lateralized in the same way. This map is created on the retina, but is also preserved in V1; the central part is at the back, while the peripheral areas are represented more towards the front. The image is upside down and backward, but your brain still responds to that information in a way that makes sense.

Cortical Magnification - This refers to the fact that some neurons in the visual cortex are responsible for processing an object of a given size in the visual field as a function of the location of the stimulus. Conversely, something in the peripheral view tends to be processed by fewer neurons.

Extrastriate Cortex - This is an area where visual input moves to. This includes the occipital lobe areas which surround the Primary Visual Cortex. The area where the information moves depends on the information.

Dorsal Extrastriate Pathway - This is the pathway that visual information takes, and it goes from V1 to the top or dorsal parts of the occipital and parietal cortex. These are processes the information about spatial orientation, depth perception, and the location, direction, and velocity of objects in space. Damage to this area can result in issues with perceiving motion visually, spatial orientation, and the guidance of movements through visual space.

Area MT - This is where motion perception relies on the most. All of the neurons here are sensitive to motion in general, but it also contain many direction-selective neurons.

Direction Selective Neurons - These neurons only fire if they sense movement in a specific direction.

Akinetopsia - Motion blindness. Damage to Area MT can cause this.

Ventral Extrastriate Pathway - This is the pathway where information about color, shape, and form is sent from V1 to areas in the bottom or ventral parts of the occipital and parietal cortex that are specialized for processing these types of inputs. This pathway also helps to process faces, symbols, colors, text, and other visual objects. Damage to this region can result in difficulty recognizing objects.

Visual Agnosia - This is the condition of inability to recognize particular objects or symbols.

Prosopagnosia - This is known as face blindness, where patients cannot identify people based on their faces. Instead, they have to rely on their voices and other cues. They can identify individual features, like hair and eye color, but struggle to piece them together in a face.

Parallel Processing - This is where the information from a stimulus is processed in different information channels and then processed in parallel by different cells at all levels of the visual system.

Pinnae - This is the outer part of the ear.

Tympanic Membrane - This is where the sounds bounce off of, also known as the eardrum.

Middle Ear - This is the part of the ear that transforms the pressure waves of air into physical movements.

Ossicles - These are the tiniest bones in the body and are found in the ear.

Eustachian Tubes - These tubes connect the Middle Ear and the back of the throat. These tubes can be congested during an infection.

Malleus - This is one of the ossicles and comes from the Latin word hammer.

Incus - This is one of the ossicles and comes from the Latin word Anvil.

Stapes - This is one of the ossicles and comes from the Latin word Stirrup.

Cochlea - This is a part of the ear whose name comes from the Latin word meaning snail. It transduces sounds and has the semicircular canals which transduce the movement of the head.

Semicircular Canals - These are canals in the Cochlea that discern how the head moves.

Utricle and Saccule Structures - These are structures that, along with the inner ear, help to keep balance and constitute a significant part of the vestibular system.

Labyrinth - This.is a part of the inner that encases many other structures in the inner ear. It is made of a bony, hollow structure that protects the inner ear.

Oval Window - The stapes push against this flexible membrane, which then transfers the physical movement to the liquid inside of the membrane.

Scala Vestibuli - This is the top part of the liquid section inside the Cochlea.

Scala Media - This is the middle part of the liquid section inside the Cochlea.

Scala Tympani - This is the bottom part of the liquid section inside the Cochlea.

Basilar Membrane - This membrane separates the Scala Tympani from the Scala Media. This membrane has varying widths and stiffness across so that each section will resonate with a different frequency. It is stiffer and narrower outside of the spiral and is the floppiest and broadest at the center or apex of the spiral. High pitches sound vibrate the outer section of the cochlea and lower pitch sounds vibrate the inside of the spiral.

Organ of Corti - This is where auditory transduction takes place. This organ contains special hair cells.

Stereocilia - These are hairlike structures found on neurons in the Organ of Corti that are used for auditory transduction.

Tectorial Membrane - is a gelatinous membrane that extends over the hair cells of the cochlea. When sound waves enter the cochlea, they cause the hair cells to vibrate.

Endolymph - This is the substance that. the hair cells and the Organ of Corti are bathed in, and is very light in potassium ions. This substance fills the scala media.

Inner Hair Cells - The stereocilia of these cells are bent back and forth as the organ of Corti moves, which opens and closes small ion channels. When the cells bend towards the tallest cell, a channel opens and allows an influx of potassium. This depolarization causes voltage-gated calcium channels to open in the basal end of the hair cell, which may create an action potential.

Tip Links - These are ion channels in the inner hair cells that open and close with movement.

Outer Hair Cells - These cells are not meant to transduce sounds; instead, they receive a feedback signal from the inner hair cells and expand and contract their neuronal membranes. This makes the cells larger and smaller and thus changes the size of the Tectorial Membrane, amplifying or dampening the response of the inner hair cells to specific frequencies.

The Auditory Pathway - This is the pathway that audio information travels across in the brain. It has many different stops at brainstem nuclei and alternative pathways connecting them all. Moth nerves process input from both ears at the cochlear nerve, unlike the visual system, which keeps the left and right eyes separate.

Cochlear Nerve - This is where audio information from both eyes mix.

Intraneural Intensity Differences - This is one way the neurons detect where sound comes from since your ears do not provide a spatial map like the eyes. Another part is using the time it takes for sound to go from one side of the head to another.

Inferior Colliculus - This is where all of the ascending audio pathways converge.

Medial Geniculate Nucleus - This is where audio signals are sent after going to the Inferior Colliculus. It is made up of many different sub-regions that have a variety of different cell types connecting to other regions. This part of the brain is thought to influence the direction and maintenance of attention.

Insular Cortex - This is where the Primary Auditory cortex is found. It is tucked between the temporal and parietal lobes.

Primary Auditory Cortex(A1) - This is found in the insular cortex, and takes its input from the MGN to the fourth layer of the cortex. Output from this area targets various other auditory critical processing areas, including language and speech processing. This region also has a map of the primary auditory cortex, and it matches the mapping of the basilar membrane and is organized by pitch as a tonotropic map. Most neurons here also have a frequency to which they will maximally respond. A surprising amount of this area must be damaged for hearing loss to occur, while damage to the cochlea or inner ear is much more likely.

Sweet, Sour, Bitter, Salty, Umami - The five tastes.

Kikunae Ikeda - He was the scientist who discovered the taste of Umami. He got this as it was a significant flavor of seaweed, which is a typical dish in Japan.

Umami - This type of flavor indicates the amino acid L-Glutamate.

Glutamate - This is an amino acid found in Umami and binds to bipolar cells.

Sweet - This type of flavor indicates the presence of high-calorie foods and sugars.

Sour - This type of flavor indicates the presence of vitamins and minerals.

Salty - These types of foods are necessary for maintaining homeostasis.

Papillae - These are the small bumps on the tongue.

Taste Buds- These are the primary sensory cells in the taste system, and they are much smaller than the papillae and are found in clusters near and among the papillae. These are barrel-shaped and contain many sensory cells.

Tastant - This is a taste particle of food that binds to the taste receptors on the taste cells.

Taste Cells - Each of these cells has a specific type of taste receptor for one of the five tastes. Therefore, any method to depolarize this cell via a tastant or other mechanism will produce that sense of taste. These cells do not fire action potentials, but the transduction for each type of these cells is different and has its way of depolarizing the cell. They also become less responsive to pain. However, this aspect is not well studied.

Salt and Sour Taste Cells - For these types of cells, the tastant enters the cell via an ion channel and depolarizes it. (Sodium Channels or Hydrogen Ion Channels that induce Potassium Leak Channels).

Bitter Cells - These cells bind to specific G-protein coupled receptors instead of primary ion channels. This cell gives off the taste of L-glutamate, activating the PLC Pathway and triggering the production of IP3 second messengers, which mid to special receptors deep inside the cell to release intracellular stores of Calcium Ions, triggering the voltage-gated calcium channels to allow even more calcium into the cell.

Sweet Cells - These cells bind to specific G-protein coupled receptors instead of primary ion channels. In naturally occurring sweet compounds like saccharides(sucrose), the activation of GCPRs depolarizes taste cells by activating a molecule to trigger a second messenger, which closes nearby K+ channels. Artificial sweeteners activate different G proteins and follow the same path as bitter and Umami Cells.

Umami Cells - These cells bind to specific G-protein coupled receptors instead of primary ion channels. This cell gives off the taste of L-glutamate, activating the PLC Pathway and triggering the production of IP3 second messengers, which mid to special receptors deep inside the cell to release intracellular stores of Calcium Ions, triggering the voltage-gated calcium channels to allow even more calcium into the cell.

Cranial Nerves - These are bundles of axons that connect the brain to the face and head since these body regions do not use the spinal cord to send signals like the limbs and torso do.

Nerves 7,9,10 - These are the three cranial nerves that bring taste and information about other vital functions in the mouth, throat, and face and information to the brain.

Gustatory Nucleus - This is where the taste information targets after going through the cranial nerves. This part of the brain is also found in the medulla.

Primary Gustatory Cortex - This is where taste information goes after the gustatory nucleus, found between the temporal and parietal lobes.

Olfactory Epithelium - This is a large cluster of cells lining the top and back of the nasal cavity. This area comprises basal cells and support cells to provide structure, as well as olfactory receptors to be transduced by the olfactory system. There are about 12 million olfactory receptors distributed among hundreds of different types of receptors that each respond to different odors. Most dogs have about a billion receptors, and bloodhounds have 4 billion.

Basal Cells and Support Cells - These cells are found in the Olfactory Epithelium, and they have specialized dendrites where airborne particles may bind olfactory receptors to be transduced by the olfactory system.

Smell Receptor Cells - These cells have dendrites that extend into the sensory epithelium, with many hair-like cilia extending outwards that are covered with receptors for smell particles. These smell particles dissolve in the mucus layer covering the olfactory epithelium. Rodents have the most enormous amount of different odorant receptors, making this the largest known gene family in any mammal.

Golf - This is the unique protein all olfactory cells use for transduction.

Nasal Signal Cascade - This is the cascade for the sense of smell. It starts with the activated G protein subunit beginning to stimulate adenylyl cyclist to produce cyclic adenosine monophosphate from ATP in the cell. This second messenger bonds to special cAMP-gated ion channels in the cell, allowing sodium and calcium to flow into the cell. These ions, in turn, trigger calcium-gated chloride ion channels to open, which allows the chloride to flow out of the cell. This creates an action potential, which then travels to the olfactory bulb.

Cribriform Plate - This is the thin sheet of protective bone that the axons of the olfactory receptor pass through to synapse in the olfactory bulb.

Olfactory Bulb - This area has approximately two thousand glomeruli. Many axons converge to a single glomerulus in this area. It seems that receptor neurons that express a particular receptor converge on the same glomerulus, keeping the information for that odor in a specific location within the olfactory bulb.

Olfactory Nerve - This is the pathway through which the olfactory bulb sends information to the brain. It is also known as cranial nerve 1. Olfactory Signals are the only ones directly sent to the cerebral cortex; other sensations are relayed through the thalamus.

Glomeruli - These are small spherical structures where the olfactory receptor axons terminate onto the next neuron in the pathway.

Olfactory Cortex - This is one of the targets for olfactory signals and is located in the temporal lobe. Still, smell signals go to other areas like the hippocampus and the amygdala.

Population Coding - This is the process of having large numbers of broadly tuned neurons identify and encode particular stimuli. This can be helpful in the senses sense, as even if one cell does not work, the rest of the cells can still send the entire message.

Somatosensation - This is the sensory category that includes all sensations received from the skin and mucous membrane, including touch, pain, and temperature, as well as sensations from the limbs and joints.

Epidermis - This is the outer layer of the skin in mammals and serves as a barrier to water and pathogens.

Dermis - This is a thicker layer found under the epidermis that contains blood vessels, sweat glands, and other essential glands and structures.

Subcutaneous Layer - This is a layer of skin under the dermis. This fatty layer contains blood vessels, connective tissue, and the axons of the sensory neurons that are our focus.

Mechanoreceptors - These receptors provide information about touch, pressure, and vibration. These are Meissner’s corpuscles, Pacinian corpuscles, Merkel’s Disks, and Ruffini’s corpuscles. These receptors are opened with physical force instead of voltage or chemicals. These mechanoreceptors are connected to relatively large, myelinated axons, critical for rapid transmission to the brain, except for pain and temperature.

Pacinian Corpuscles - These are the largest and most well-known corpuscles, and they feature many layers of insulation at the tip, like an onion. The layers allow the receptor to adapt to a touch stimulus over time. There is a burst of action potential at the onset, but as the fluid redistributes, the pressure is reduced on the receptor. This receptor is meant to sense vibration.

Meissner’s Corpuscles - These mechanoreceptors are much smaller than the Pacinian corpuscles and tend to be located in the ridge of glabrous skin, like that found on your hands, fingers, lips, or soles of the feet. These receptors are meant to transduce information about low-frequency vibration or flutter. They can also rapidly adapt, like Pacinian Corpuscules.

Glabrous - Hairless.

Merkel’s Disk - This can be found in both skin that has hair and glabrous skin. This type of receptor fires action potentials for the whole stimulus duration. These nerve endings are exceptionally high in density in the fingertips and lips, and they transduce light touch.

Riffini’s Endings - This receptor does not adapt quickly and fire action potentials during the duration of the stimulus. They are found in all skin and detect tissue stretch.

Touch Receptive Fields - The receptive fields for the two receptors close to the surface are small and can give price definition with sharp edges; however, the field with the Ruffini’s endings, and Pacinian Corpuscles lie more deeply in the dermis and subcutaneous layer, their transduction is fewer prices, and their receptive fields are more extensive, providing less precise information, like force and vibration.

Two-Point Discrimination - This is a method of finding out how much resolution out skin. This is measured by how close two objects are on this skin before your skin cannot tell they are two distinct points.

Innervated - This means that the area has a high density of mechanoreceptors.

Cervical - This is the upper part of the spinal cord and is the first part of the spinal cord.

Thoracic - This is the middle upper part of the spinal cord and is the first part of the spinal cord.

Lumbar - This is the middle part of the spinal cord and is the first part of the spinal cord.

Sacral - This is the bottom part of the spinal cord and is the first part of the spinal cord.

Dermatome - This is all of the skin that is innervated by one level or segment of the spinal cord and varies from one person to another. This can help to diagnose conditions like Shingles.

Shingles - This condition is a reactivation of the chicken pox virus. It causes a rash to appear in the dermatome where it was inactive and only that dermatome, giving a striped appearance to the rash.

Thermoreceptors - These are nerve endings that transduce temperature. They do not have any specializations to their receptors and are therefore referred to as free nerve endings. These nerves use unmyelinated, small axons, so the signals are relatively slow.

Low Threshold Receptors - Temperatures between 15 and 45 C activate these thermoreceptors.

High Threshold Receptors - Temperatures higher than 45C and below 15C activate these thermoreceptors and are perceived as painful.

Nociception - This is the neural process of injurious stimuli in response to tissue damage.

Nociceptors - These receptors are transduced at accessible nerve endings located in the epidermis, like thermoreceptors.

Capsaicin - This is a chemical that can cause hot reactions without actually being hot because the protein receptors that bind capsaicin open the same calcium channels that are activated by thermoreceptors. It is found in peppers.

Menthol - This chemical can cause cold reactions without actually being cold because the protein receptors that bind capsaicin open the same channels that are activated by thermoreceptors. It is found in cold medications.

Hyperalgesia - This is caused by a temporarily reduced threshold for pain in a damaged or neighboring area of tissue, and this is your body’s way of getting you to be gentle around a damaged area, giving it time and space to heal properly. This process begins with the emission of chemicals at the injury site and triggers inflammation.

Congenital Analgesia - This hereditary insensitivity to pain is very rare and dangerous because the organism can never learn that certain stimuli are dangerous. Genetic mutations, defects in the free nerve endings, or problems with the axon connections in the brain can cause this.

Pathway of Touch - This path goes from the afferents to the Dorsal Root Ganglions, then they decussate and then synapse in the thalamus to then be relayed to the cerebral cortex.

Dorsal Root Ganglions - This is where the sensory neurons of the somatosensory system have their cell bodies or soma in these little bundles.

Afferents - This refers to the axons of sensory neurons.

Efferents - This refers to the axons of motor pathway neurons.

Dorsal Column Nedial Lemniscal (DCML) System - This is the system of how touch sensations travel up to the brain.

Dorsal Columns - These are the bands of white matter in which the touch information travels while in the spinal cord. Here, information about the upper and lower body are kept separate. Some axons do not synapse here and go straight to the two dorsal column nuclei. However, some do, primarily for repetitive motions, like walking. After they synapse here, they decussate immediately.

Medial Lemniscus - This is Greek for Ribbon and is the pathway that winds through the brainstem on its way to the thalamus.

Gracile Nucleus. - This is a part of the medulla where information about the touch sensations of the lower body can be found.

Cumneate Nucleus - This is where information about touch sensations from the upper body can be found and is right next to the gracile nucleus.

Contralateral - Opposite Side.

Ventral Posterior Lateral Nucleus - This is where touch signals synapse on the third and final neuron in the pathway.

Primary Somatosensory Cortex - This is where the axons of the third and final neurons travel a relatively short distance. It is the central processing area for somatosensation.

S1 - This is the primary somatosensory cortex that is located at the front of the parietal lobe and is next to the Primary Motor Cortex.

Primary Motor Cortex M1 - This works together with and is next to the S1, and both of them work together to sense the environment and respond to it.

Somatosensory Neurons - These neurons are arranged spatially or topographically so that neighboring neurons represent neighboring regions of the body or face. This organization is at every level of the DCML and the anterolateral spinothalamic pathway.

Anterolateral Spinothalamic Pathway - This is the pathway that has the preservation of spatially organized somatosensory neurons.

Sensory Honomunculus - This is the Honomculus that is displayed in S1. The Latin word means “little man”.

Lower Motor Neurons - These are neurons that synapse directly onto the muscles, and they release acetylcholine as their neurotransmitter in the neuromuscular junction. Cell bodies for these neurons are often found in the spinal cord with only their axons extending out of the vertebrae forming the bottom or ventral spinal root.

Myofibrils - Upon receiving the signal from the acetylcholine, calcium channels in the cell open and start a chain reaction within this part of the muscle cells causing the filaments to lengthen or shorten.

Upper Motor Neurons - These are cells that provide the information to the lower motor neurons and they originate in the brain or brainstem.

Myotatic Reflex - This is a type of reflex that does not communicate with the brain to produce a reaction, for example, the knee-jerk reaction.

Muscle Spindle - This is a small proprioceptive element deep within the muscle that sends information down its axon of afferent into the spinal cord via the dorsal root, where it synapses directly on the lower motor neuron for that same muscle.

Premotor Cortex and Supplementary Motor Cortex - These are regions of the brain that help with motor planning and are next to the motor cortex.

The Lateral System - These paths are where voluntary motor information is carried. This name comes from the white matter of the spinal cord, namely in the side parts of it.

Corticoculbar System - This is often included even though it does not run in the spinal cord at all, as it controls brainstem nuclei that innervate cranial muscles to control the voluntary movement of the facial muscles.

Corticospinal Tract - This is one part of the lateral system, and it runs from the cerebral cortex to the spine, beginning in the primary motor cortex. The axons of these neurons descend through the white matter of the brain and brainstem, where they form a bump on the underside of each side of the medulla. Since these bumps look slightly triangular, this is also known as the pyramidal tract. At the bottom of the medulla, the neurons decussate and descend through the spinal cord, and synapse at the lower motor neurons in the central grey matter of the spinal cord.

Monosynaptic Pathway - It is one neuron in the cortex and descends to the proper spinal cord segment for its target muscle, making these neurons the longest in the body.

Rubrospinal Tract - This is a much smaller component of the Lateral System, which is named that because it begins in a small region of the midbrain called the red nucleus after the pinkish appearance of the region. The path also decussates, but it does so at a higher level in the midbrian. This pathway plays a more significant part in the anatomy of other animals, but in primates, it mainly defines muscle tone.

Red Nucleus - This is where the Rubrospinal Tract begins and is a small midbrain region that appears pinkish.

Ventromedial Pathways - These are the motor pathways found in the center bottom of the spinal cord, direct torso, and trunk muscles and are responsible for posture and balance. These pathways begin in a variety of nuclei found in the brainstem and terminate on lower motor neurons that direct the muscles of the core and trunk. These pathways are much less distinct than the lateral pathways; some decussate, some do not, and some target lower motor neurons on both sides of the body.

Vestibulospinal Tract - This originates in the vestibular organs of the inner ear that provide information about gravity, spin, and other forces on the body and head. Some axons go up to the head, and some go down to the neck and muscles to allow the body to compensate for changes in spin or force on the head.

Tecospinal Tract - This originates in the roof or rectum of the midbrain section, where visual input is mixed with auditory and somatosensory inputs to form. cohesive map of the world.

Reticulospinal Tract - This arises from the reticular formation found in the pons segment of the brainstem and targets the torso and legs.

Basal Ganglia. - These regulate motivation, and damage to it (Parkinson’s and Huntington’s Disease) lead to motor impairment like shuffling gait or spastic twitches.

Striatum - This is a part of the Basal Ganglia and comprises the caudate and putamen.

Globus Pallidus - This is a part of the Basal Ganglia that has an internal and external section.

Subthalamic Nucleus - This is a part of the Basal Ganglia and is found under the thalamus.

Substantia Nigra - This is a part of the Basal Ganglia and is also a part of the midbrain in the brainstem.

Direct Pathway - This facilitates movement, which makes it easier to get a movement started or to keep it going. Motor input from the cortex activates the striatum, which inhibits the inhibitory neurons in the Globus Pallidus and reduces inhibition on the thalamus, which allows more movement to happen.

Indirect Pathway - This inhibits movement, and it makes sure that there is no excess movement occurring that is not wanted. Motor input from the cortex activates the striatum, which inhibits a different portion of the Globus Pallidus, which disinhibits the subthalamic nucleus, which disinhibits the other portion of the Globus Pallidus.

Dopaminergic Input from the Substantia Nigra - This decides whether the direct or indirect pathway is used to create a movement. In the Striatum, the direct pathway has D1 dopamine receptors. depolarize the cell in response to dopamine bonding, and D2 receptors hyperpolarize in response to dopamine bonding. Because of this, whenever the substantial nigra is activated, there is always an increase in motor activity because the Direct Pathway is stimulated and the indirect pathway is inhibited.

D1 Receptors - These are cells in the Substantia Nigra that depolarize in response. to dopamine bonding.

D2 Receptors - These are receptors in the Substantia Nigra that hyperpolarize in response to dopamine bonding.

Cerebral Deep Nuclei - This provides the output for the structure in the Cerebellum.

Cerebellar Cortex - This is wrinkly like the cerebral cortex and contains almost all the neurons in the cerebellum and contains almost all the neurons in the cerebellum.

Fastigial Neurons - This received input from sections of the cerebellar cortex that process vestibular, somatosensory, auditory, and visual information., its output projects to the vestibulospinal and reticulospinal tracts to integrate sensory input with motor commands to produce flexible and adaptable motor commands, and is crucial for motor coordination.

Interposed Nucleus - This plays a similar role to the Fastigial Neurons but targets the red nucleus, influencing the rubrospinal tract.

Dentate Nucleus - This is the most significant part of the cerebellar nuclei, located next to the interposed nuclei. It receives input and sends output to the motor cortex, assisting with the planning and timing of movements.

Purkinje Cells - This cell’s dendrites create a coral-like array of branches, and the dendritic tree is almost two-dimensional and almost flat when viewed from the side. They are organized in parallel, allowing single, horizontal axons to make contact with Purkinje cells at the same time. All of the output from the cerebral cortex comes from these cells.

Motor Learning - This is an unconscious learning process through repetition in which the brain and body adapt to ongoing feedback about a motor command. In this system, the Cerebellum is thought to be a feedback control system.

Section 4: Synaptic Plasticity and Memory

Synaptic Plasticity - This plasticity occurs at synapses and affects the brain’s capacity to learn, develop, store information, and grow. This idea that synapses could change is new, first proposed 1949 by Canadian psychologist Donald Hebb.

Donald Hebb - He was the first person to present the idea of synaptic plasticity in Canada in 1949. He also created the Hebbian Theory.

Hebbian Theory - This theory hopes to explain the changes in neural networks and how they are developed based on experiences.

Synaptic Strength - This is the strength of the signal at the synapse and how they become more tightly wired as they are used more often.

Ocular Dominance Columns - These are stripes of tissue across layer 4C that get their input from one eye only. David Hubel and Torsel Wiesel introduced this concept in the 1960s. They used awake cats that were fixed in place and looking at the light on a screen, and they observed that no matter where in layer 4C of V1 they paced an electrode, the neurons there seemed to fire action potentials in response to input from either eye.

Monocular Deprivation - This is where one eye of an organism is sealed shut soon after birth such that the sealed eye never gets light during the organism’s development. They found that the dominance column shrank nearly entirely away, while the column for the open eye seemed to fill the space. This effect can be seen even for a short period.

Critical Periods - These are essential stages of development where plasticity is uniquely high and developmental fade is influenced potentially for an entire lifetime based on the environmental inputs they receive. These stages can be seen in visual and auditory development. Random Fact: Putting an eye patch on an adult’s eye for a few hours will affect the eye’s contribution to binocular vision in VI. However, the effect is relatively short-lived.

Somatosensory Cortex - This area undergoes significant change due to cortical plasticity.

Homunculus - This is a representation of a map of the body in the brain.

Whiskering - This is the motion of whiskers back and forth and relay information to the brain.

Barrel - This is a little dot in the rodent’s primary somatosensory cortex.

Barrel Field - This is the entire area of whistler representation.

Phantom Limb Syndrome - This disease gives sensations in the skin region whose cortical representations border the missing body part. It is common to evoke this syndrome in a missing hand or arm touching the face, as the face representation is right next to the hand in the S1 homunculus.

Santiago Ramon y Cajal - He was a scientist who first speculated that learning was essential to the growth and development of new connections between neurons in 1894.

Eric Kandel - He was a scientist who, in the 1960s, used new technology to study memory circuits in very simple animals like the sea slug Aplysia California. He also later earned a Nobel Prize.

Aplysia California - These animals have a soft underbelly where their gill is located. If any part of their underbelly is touched, they retract the bill into the body cavity to protect it.

Habituation - This is learning to ignore a stimulus that lacks meaning(as it is neither good nor bad nor linked to anything else)

Synaptic Weakening - This is what happens during habituation, and it makes the postsynaptic receptor less responsive to signals.

Sensitization - This is the opposite of habituation, and it is learning that a stimulus is essential and strengthens the behavioral response.

Siphon Sensory Neuron - This stimulates the production of a second messenger we’ve seen before, cAMP, which then activates PKA and then phosphorylates many proteins, probably including nearby K+ channels, which alter their activity to reduce the probability of then opening them, reducing the possibility of an action potential.

Electrophysiological Recordings - This is a method of experimentation that measures whether the strength of a synapse changes as a result of an experiment. This is done by recording the membrane potential of the presynaptic neuron.

Long-term potentiation (LTP) - This is the strengthening of a synapse that is usually based on changes in the postsynaptic receptors. This can last for weeks in living mammals and potentially last for a lifetime. This change is related to the memory storage process in the hippocampus, and interfering with this process makes it difficult for the organism to remember what they were doing since the hippocampus is responsible for consolidating memories. Increasing this can induce “super memory” for a short period.

Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid(AMPA) receptor - glutamine binds to this receptor in the postsynaptic cell in normal conditions. These are also isotropic, allowing sodium to flow into the cell, depolarizing it, and making it more positive.

N-methyl-D-aspartate(NMDA) receptor - If there is enough cell depolarization, the positive charges will repel the positively charged magnesium, allowing ions to flow through this receptor. While AMPA only lets sodium through, this type lets sodium and calcium into the postsynaptic cell.

Calcium Calmodulin-Dependent Protein Kinase(CaMKII) - This is a second messenger enzyme that uses multiple mechanisms to shepard new APA receptors to be inserted into the postsynaptic neuronal membrane. This substance can also phosphorylate existing AMPA receptors making them work more efficiently, and works to change the structure of the postsynaptic part of the synapse, leading to changes in the dendritic spine shape. Additionally it phosphorylates CREB, a transcription factor, which is critical for producing the new proteins that will be necessary to maintain these structural changes long term.

CREB - This is a transcription factor which is critical for producing the new proteins that will be necessary to maintain these structural changes long term.

Long-term Depression - This is the opposite of LTP and can be caused by other signals removing AMPA receptors from the postsynaptic membrane, weakening their synaptic connection.

Factual Memory -These are Memory of facts, like what is the date of Irving.

Amygdala,Hypothalamus,Cingulate Gyrus - Parts of the limbic system.

H.M. - This was a young man who had severe epilepsy who underwent brain surgery in the 1950s to remove his hippocampus to control his seizures. Beacuse of this H.M. could not form new memories, but remembered all of his old ones.

Entorhinal Cortex - This has six layers, like most other regions of the cortex, and helps process perceptual and sensory information before sending it along. The hippocampus only has three layers making it nore simple than other regions of the brain.

Perforant Path - This is the bundle of entorhinal cortex cell axons that send information to the dentate gyrus.

Dentate Gyrus - This is a part of the hippocampus that is famous for being one of the few locations in the human brain where evidence of neurogenesis can be found. This is also the first region that information from all of the sensory circuitry comes together and forms full and complex representations, such that the formed memories can associate those variable stimuli together.

Neurogenesis - This is the birth of new neurons.

Mossy Fibers - These are granule cell axons.

Granule Cells - These are small neurons in the dentate gyrus.

Ammon’s Horn - This is where the mossy fibers synapse. In Latin, this place is called Cornu Ammonis, and then neurons synapse specifically in CA3.

Pyramidal Cells - These are large neurons that are similar to the large cells found in the six layered regions of the cerebral cortex.

Schaffer Collaterals - These are axons that are thought to be crucial for the consolidation of short term memory into long term memory.

Fornix - This is the projection of the axons of the pyramidal cells that brings information from the hippocampus to a range of deep brain regions.

Short term memory - This type of memory requires constant attention and does not last. You can retain around 5 to 9 items in their short term memory. The prefrontal cortex, especially the top and sire regions are important to this type of memory.

Long term memory - This is the result of three different processes: encoding, storage, and retrieval of information. Encoding is the act of learning new information, storage is the process of the brain filing away this new information, and retrieval is the process of remembering the information.

Explicit Memory - This is any memory that can be recalled.

Semantic Memory - These are memories without any context or emotions.

Episodic Memories - Memories that are related to a specific episode in your life.

Implicit Memory - This is unconscious and unlearned memory, which takes longer to learn but you remember for life. For example, riding a bike. This does not require the hippocampus.

Procedural Memory - This is the memory of learning motor skills. This involves motor regions in the cerebellum and is a type of implicit memory that relies on the basal ganglia.

Priming - This is when exposure to a stimulus influences your memory.

Classical Conditioning - This is the process of getting a subject to form an association between a meaningful stimulus and a neutral item.

Section 5: Technology and Neuroscience

BRAIN - This is a new research effort that stands for Brain Research through Advancing Innovative Neurotechnologies. It was created in 2013 by President Obama and focused on giving scientists the tools they need to get a dynamic picture of the brain in action. The Initiative funding began in 2014, gaining 46 million dollars for developing new tools to analyze the brain. The outcomes have included the Human Connectome Project and new microscope technology.

Connectome - This is a map of neural circuit structure and function.

Perturbation - This is the process of changing or altering something in the brain and then seeing what changes occur in the resulting behavior.

Noninvasive Methods - These are methods of getting information from the brain without having to physically alter it.

Lesion Studies - These types of experiments are still done on animals but are often considered unethical to do this.

Paul Broca - He was a French surgeon who visited a patient in the hospital who was suffering from a progressive impairment in his ability to speak and soon died. During the patient’s autopsy, Broca discovered a lesion to the left frontal area of the patient’s cerebral cortex from syphilis. An area of the brain is named after him.

Electrical Brain Stimulation(EBS) - This is the insertion of an electrode implant into a subject’s brain to stimulate certain neurons. It was used as early as the beginning of the nineteenth century.

Deep Brain Stimulation - This is using implanted electrodes to treat Parkinson’s disease and tremors.

Electroshock Therapy - This is the process of using electrodes on the scalp surface for treatment-resistant major depression.

Transcranial Direct Current Stimulation (tDCS) - This uses one positive and one negative electrode to run current through the brain, increasing or decreasing activity in particular regions. The stimulation produced by this method is very small. It may have a small impact, but research is being conducted on it as it is an easy and inexpensive alternative to other methods.

Transcranial Magnetic Stimulation - This is the process of inducing a magnetic field to modulate the excitability of a region of the cortex. This magnetic field induces an electric field within the cortex, causing neurons to depolarize or hyperpolarize depending on the field.

Optogenics - This is the process of introducing foreign genes that express the code for ion channels that open or close in response to light, like those found in the retinas.

Channelrhodopsin-2 - This is a light-absorbing pigment that also acts as an ion channel. When it is artificially injected into neurons, it opens ion channels that are sensitive to blue wavelengths of light.

Intracellular or Single Unit Recording - This is the process of recording from the brain that involves an electrode implanted in a particular neuron.

Extracellular Recording - This is the process of recording the membrane potentials around a cell, and is more popular than Intracellular Recording.

Phrenology - This was a baseless but popular method of early neuroimaging in the nineteenth century, in which a practitioner would feel the bumps on a subject’s skull to explain their neurological traits.  This technique was created by Franz Joseph Gall who lived from 1758 to 1828 and believed that a persons personality traits could be derived from particular regions of the brian and that they could be read from the scalp.

Theory of Localization - This is an idea that particular areas of the brian have particular unique jobs to do.

Electroencephalogram - This was the first noninvasive way to study the brain and was invented by German psychiatrist Hans Berger in the 1920s, and Berger lived from 1873 to 1941. Modern day versions of this instrument use small metal disks called electrodes that are held together by a fabric cap and attached to the surface of the scalp with a little sticky jelly-like material. Using this technology, Berger was the first person to identify the different types of electrical waves that are present in the typical functioning brain and showed differences in individuals who might have mental conditions.

Dipole - This is an area of negative charge next to an area of positive charge. Most large neurons in a given section of the cerebral cortex tend to be in alignment with each other, creating this.

Event Related Potential - This is the process of scientists looking at the brain waves that resulted from one specific stimulus shown to a subject.

N170 - This is the brain wave reaction of seeing a human face, and the amplitude is based on the type of face shown, with emotional faces having higher amplitudes. This is also changed in schizophrenia patients and other patients with neurologican conditions.

Spatial Resolution - This is the accuracy of pinpointing a certain region of the brain where activity is coming from.

Magnetic Resonance Imaging - This is a medical imaging technique that uses a strong magnetic field to produce detailed images of the inside of the body or other organism. It was one of the biggest breakthroughs of cognitive neuroscience.

Radio Frequency Pulse - This is a pulse of energy that only lasts a moment and is used in MRIs to help the cells create a radio signal that can be detected by the MRI.

Functional MRI - These are maps of the changes in blood flow in real time on an MRI.

Fusiform Face Area - This is a part of the brain that is focused on recognizing faces, and is located in the lower surface of the temporal lobe. It is only the size of a brape and was first found with fMRIs.

Brain Machine Interface - This is a system that allows a person to control a device or machine using only their thoughts.