Neuroexam 1

Brainstem

Connects cerebrum to spinal cord and cerebellum (in descending order: midbrain, pons, and medulla oblongata)

the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions

Midbrain (mesencephalon)

• receives sensory and motor information from the rest of the body.

• superior colliculi: visual stimuli

• inferior colliculi: auditory stimuli

Medulla Oblongata

Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.

Pons

A brain structure that relays information from the cerebellum to the rest of the brain.

• key structure for motor control

• also regulate respiration and heart rate

Cerebellum (little brain)

Balance and coordination

• predicting the consequences of movement, timing, attention, learning

• key in motor learning

cerebellar ataxia

Condition associated with damage to cerebellum (lack of balance and coordination)

cerebellar agencies

Condition in which cerebellum isn't present, affects walking, talking, and social behavior.

Diencephalon

Central portion of the brain. superior to brainstem, inferior to corpus callous and cerebral cortex.

• epithalamus, thalamus, subthalamus, and hypothalamus

Thalamus (relay station)

Processes info from each sensory modality (except smell), receives info from the cortex and transmits it to motor systems

• 30 clusters of nuclei that transmit specific kinds of cognitive info (sensory, motor, auditory, touch, etc)

Hypothalamus

A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

• influences release of pituitary hormones - if in a stressful situations, brain signals pituitary gland to release hormones that will travel across blood stream

Endocrine system

System of glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.

• hypothalamus

• pituitary

• pineal gland

Pineal gland

Near center of the brain, tucked where the left and right thalamus come together

• secrets melatonin - important in regulating sleep and wakefulness

Basal Ganglia

Group of forebrain structures critical for voluntary movement - for autonomic and habitual responses. Important for learning new behaviors, especially those reinforced by rewards

Striatum

Largest structure of basal ganglia the caudate nucleus and putamen together - related voluntary movements

Globus pallidus

Component of the basal ganglia that connects to the thalamus which relays information to the motor areas and the prefrontal cortex

• control conscious and proprioceptive movements

Limbic system

Neural system located below the cerebral hemispheres; associated with emotions and drives

• includes the amygdala,m hippocampus, hypocampys, and basal ganglia

Amygdala

Recognizes signs of threats and emotional significance and activates the sympathetic nervous system

• anterior tip to hippocampus

Hippocampus

a neural center located in the limbic system; helps process explicit memories for storage

• temporal lobe

Cerebral cortex

outer region of the cerebrum, containing sheets of nerve cells; gray matter of the brain. area underlying the cerebral cortex contains white matte

• gyro/gyrus: hills

• sulci/sulcus: valley

longitudinal fissure

separates left and right hemispheres

occipital lobe

A region of the cerebral cortex that processes visual information -no clear line where it ends and where the temporal and parietal lobe begin

Parietal lobe

A region of the cerebral cortex whose functions include processing information about touch.

• tactile/sensation

• separated from frontal lobe by central sulcus, is posterior to the central sulcus

Temporal lobe

A region of the cerebral cortex responsible for hearing, language, speech, emotion, and memory.

• separated from the frontal and parietal lobe by lateral sulcus

• hippocampus, and amygdala lie within subcortical areas of temporal lobe

Frontal lobe

A region of the cerebral cortex that has specialized areas for movement, abstract thinking, planning, memory, and judgement

Prefrontal lobe

portion of the frontal cortex involved in higher-order thinking, such as memory, moral reasoning, and planning

• anterior part of prefrontal lobe

MRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scans show brain anatomy.

• perturbation of water molecules without a radio frequency pulse

Structural MRI (Magnetic Resonance Imaging)

Can see volume, area, and cortical thickness of brain/structures

Functional MRI (fMRI)

technique that uses magnetic fields to visualize brain activity using changes in blood oxygen level

RSI (restriction spectrum imaging)

Method of brain imaging that is based on less diffusion of water molecules inside the cell then outside the cell

• can estimate cell density

Electronencephalogram (EEG)

an amplified recording of the waves of electrical activity sweeping across the brain's surface. These waves are measured by electrodes placed on the scalp.

Axial plane (superior to inferior)

A horizontal flat surface dividing the brain into upper and lower parts -hamburger bun or bagel

Coronal plane (anterior to posterior)

Method of slicing brain: like loaf of bread

Sagittal plane (left to right)

Method of slicing brain that separates the left and right of the brain

Dorsal and ventral

Similar to anterior and posterior

Rostral and Caudal

From head towards end of spinal cord

Central Nervous System (CNS)

brain and spinal cord

Spinal cord

a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain

• vertebrae protect the spinal cord

• meninges (protective tissue) protect spinal cord and brain within the vertebrae

Central canal (Spinal cord)

center of spinal cord that runs through spinal cord to brain ventricles which contains cerebrospinal fluid

Peripheral nervous system (PNS)

the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

• spinal nerves

Somatic divison (PNS)

Communicates information between CNS and body parts (skin and muscle) Controls body movements Touch and sensory information

Autonomic division (PNS)

CNS communicates with organs and occurs unconsciously Respiration, heart rate, digestion, etc

Sympathetic division (AD of PNS)

fight, flight, or worry (often responds to stress and threats)

Parasympathetic division (AD of PNS)

rest and restore

Cranial nerves

12 pairs of nerves that carry messages to and from the brain

• between your neck, brain, face, and torso

• help you hear, taste, smell, and feel sensations

Glial (Glia) cells

cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning and thinking

Oligiodendrocytes (glial)

Form myelin around axons in CNS (helps info travel faster)

• single cells can be wrapped around several axons (up to 50)

• one of the major cell types in the cerebral white matter

• myelinated surface of axons = internodes/non myelinated

• non myelinated= nodes of ranvier

Schwann (glial)

Surrounds neuron by covering them with a myelin sheath. Major glial cell in peripheral nervous system (PNS)

• single axon

Microglia (glial)

CNS: very tiny, clean debris left by neurons that are damaged/dead and synapses that aren't used

• alerts brain to injury or disease, then gets rid of toxins or pathogen

Radial glia (glial cells)

CNS: Provide scaffolding by helping newly born neurons

• responsible for production of neurons in the cerebral cortex

Astrocytes - STAR (glial cells)

CNS: carry nutrients, like glucose to neurons. provide the cellular link between neurons and blood brain barrier

Neuron

a nerve cell; the basic building block of the nervous system

Dendrite

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Cell membrane of neuron

• forms the border of a neuron and acts to control the movement of substances into and out of the cell

• neurons need energy to create ionic concentration gradients, get energy from glucose, which turns into ATP

cell body (soma)

contains the nucleus and other parts of the cell needed to sustain its life

• "factory of the cell"

Axon (nerve fibre)

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

• carries nerve impulses away from the cell body

Axon terminal

The endpoint of a neuron where neurotransmitters are stored.

• make synaptic connections with another nerve cell

Ganglia

Group of neurons

Plasticity

the brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience

corpus callosum

the large band of neural fibers connecting the two brain hemispheres and carrying messages between them

• white matter tracts

Medial

toward the midline (nose back to head)

Lateral

Away from the midline (ear)

Grey column - gray matter shaped like butterfly

Contains cell bodies of neurons whose axons communicate with nearby body parts

• contains cell bodies of interneurons, motor neurons, neuralgia cells, and unmyleinated axons

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

how the message is communicated

Dendrite, cell body, axon, axon terminal, synaptic cleft

excitatory input

Information entering a neuron that signals it to respond and fire

Inhibitory input

Information entering a neuron that signals it not to respond and fire

Intracellular fluid

Fluid within the neuron. Contains negatively charged proteins (Prot-) as well as potassium ions K+

Extracellular fluid

Fluid outside the membrane contains high concentrations of sodium (Na+) and chloride (Cl-)

What happens when a neuron is fired?

Sodium channels are embedded within the membrane. Once the neuron is active/depolarized enough the sodium channels open and Na+ enters

One reasons why Na+ flow into neuron after channels open?

• Diffusion: movement of a substance from an area of high concentration to a region of lesser concentration. Na+ enters the neuron because inside of the neuron is less concentrated with Na+ than the outside. Na+ diffuses across membrane toward the less concentrated inferior of the neuron

Another reason why Na+ flow into neuron after channels open?

Electrostatic pressure: Opposites attract, drives positively charged Na+ to the negatively charged inside of the neuron

sodium-potassium pump (how does neuron maintain a higher Na+ concentration outside compared to inside)

For every 2 K+ ions pulled into the neuron, 3 Na+ are pumped out. Without the activity of the sodium potassium pump, Na+ would not enter the neuron bc there wouldn't be diffusion or electrostatic pressure.

Action potential

explosion of electrical activity that is created by a depolarizing current. when a neuron fires an action potential ion channels open began to open. The action potential sweeps along the neuron

Action potential threshold

Critical level of depolarization required to trigger an action potential - about -55mV

Membrane potential/voltage

difference in charge inside compared to outside of neuron.

• the resting membrane potential of a neuron is usually -70mV

Voltage-gated channels

When membrane potential endures enough depolarization to reach -55mV, these ion channels began to open at initial segment (axon hillock) of the axon

Depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

• excitatory

Polarization

Membrane potential/action potential becomes more negative, trying to prevent neuron from firing

• inhibitory

how neurotransmitter/action potential gets to axon terminal without sodium channels in axons?

Action potential jumps from one to another - myelin makes the process faster.

Myelinated axons: glial cells that form bands of myelin that surround axon nodes of ranvier= gap in myelin sheath of a nerve

Saltatory conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

Conduction velocity

the speed at which an action potential is propagated along the length of an axon

refractory period

a period of inactivity after a neuron has fired

• the brief inactivation gate of the Na+ channel

Order for sensory neurons in skin

Dendrite, axon, axon terminal, spinal cord

Axon hillock

The conical region of a neuron's axon where it joins the cell body; typically the region where nerve signals is generated - where action potential is the highest

neuron firing rate

of action potentials per second

Synthesis of neurotransmitters

Begin with amino acids or other nutrients from dietary proteins. The axon terminal turns amino acids into neurotransmitters. they are then packaged into vesicles.

for larger neurotransmitters- cell body, vesicles, axon terminal

exocytosis

At the axon terminal. merging of the vesicles with the membrane leading to the secretion of the contents (neurotransmitters) into the synaptic cleft.

Autoreceptor (negative feedback loop)

When neurotransmitters bind to presynaptic neuron's receptors. This can signal presynaptic neuron to slow down firing, like brakes on a car.

Reuptake

clears neurotransmitters from synapse. in presynaptic membrane, transporter proteins transport neurotransmitters molecules back into presynaptic terminal to be packaged into vesicles

degradation/inactivation

neurotransmitters molecules in synapse or presynaptic terminal may be inactivated by enzymes or broken into inactive components.

What is the main excitatory and inhibitory neurotransmitters?

Glutamate and GABA

• glutamate has relation to episodic seizures -GABA has relation to anxiety medicine

neuromodulators

a neurotransmitter that acts to modulate activity in a large number of neurons rather than in a single synapse. Act at a distance

• dopamine, serotonin, and norepinephrine.

Volume transmission

Phenomenon characterized by the diffusion of a chemical signal (e.g., a neurotransmitter) through the extracellular fluid to reach target cells at some distance from the point of release.

• ability of neurochemical to act as a distance well beyond its site

excitatory neurotransmitters

Binds to receptor on the postsynaptic neuron. Causes ion channels within receptor to open, this allows Na+ and other positive ions to enter neuron and cause depolarization

Neurotransmitter gated Na+channels

Only opens when a neurotransmitter binds to it

excitator postsynaptic potential (EPSP)

When Na+ enters and causes depolarization in the membrane. Increases the membrane potential and increases likelihood of neuron firing

inhibitory neurotransmitters

binds to receptors that cause opening of Cl- chlorice or cause K+ channels to open and they flow out of neuron

inhibitory postsynaptic potential (IPSP)

Causes hyperpolarization of postsynaptic neuron, this decreases the likelihood of neuron firing as the membrane potential continues to decrease

Spatial summation

When EPSP or IPSP occur at different places on dendrites and cell body, and they add together

• if this causes depolarization that exceeds firing threshold at the axon's initial segment, voltage-gated Na+ open, and action potential occurs

• if IPSPs add, this strongly inhibits neuron from firing

Temporal summation

neurotransmitters bind and dissociate from receptors, allows other neurons to bind to the same receptor.

if neurons binds to a receptor quickly enough in rapid succession, ESP's and ISPs can add - affecting neuron will fire or not