Chapter 3 Psych

Action Potential

A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.

Axon

Part of the neuron that extends off the soma neurons; main output of the neuron.

Brain Stem

The “trunk” of the brain comprised of the medulla

Broca’s Area

An area in the frontal lobe of the left hemisphere. Implicated in language production.

Central Nervous System

The portion of the nervous system that includes the brain and spinal cord.

Cerebellum

The distinctive structure at the back of the brain

Cerebrum

Usually refers to the cerebral cortex and associated white mattermthe subcortical structures.

Contralateral

Literally “opposite side”; used to refer to the fact that the two hemispheres of the brain process sensory information and motor commands for the opposite side of the body (e.g. the left hemisphere controls the right side of the body).

Corpus Callosum

The thick bundle of nerve cells that connect the two hemispheres of the brain and allow them to communicate

Dendrites

Part of a neuron that extends away from the cell body and is the main input to the neuron.

Diffuse Optical Imaging (DOI)

A neuroimaging technique that infers brain activity by measuring changes in light as it is passed through the skull and surface of the brain.

Electroencephalography (EEG)

A neuroimaging technique that measures electrical brain activity via multiple electrodes on the scalp

Frontal Lobe

The front most (anterior) part of the cerebrum; anterior to the central sulcus and responsible for motor output and planning language

Functional Magnetic Resonance Imaging (fMRI):

A neuroimaging technique that infers brain activity by measuring changes in oxygen levels in the blood.

Limbic System

Includes the subcortical structures of the amygdala and hippocampal formation as well as some cortical structures; responsible for aversion and gratification.

Myelin Sheath

Fatty tissue of electrical impulses among neurons.

Nervous System

The body’s network for electrochemical communication. This system includes all the nerves cells in the body.

Neurons

Individual brain cells

Neurotransmitters

Chemical substance released by the presynaptic terminal button that acts on the postsynaptic cell.

Occipital Lobe

The back most (posterior) part of the cerebrum; involved in vision.

Parietal Lobe

The part of the cerebrum between the frontal and occipital lobes; involved in bodily sensations, visual attention, and integrating the senses.

Peripheral Nervous System

All of the nerve cells that connect the central nervous system to all the other parts of the body.

Positron Emission Tomography (PET)

A neuroimaging technique that measures brain activity by detecting the presence of a radioactive substance in the brain that is initially injected into the bloodstream and then pulled in by active brain tissue.

Soma

Cell body of a neuron that contains the nucleus and genetic information synthesis.

Spatial Resolution

A term that refers to how small the elements of an image are; high spatial resolution means, the device or technique can resolve very small elements; in neuroscience it describes how small of a structure in the brain can be imaged.

Split-brain Patient

A patient who has had most or all of his or her corpus callosum severed.

Synapses

Junction between the presynaptic terminal button of one neuron and the dendrite, soma of another postsynaptic neuron.

Synaptic Gap

Also known as the synaptic cleft; the small space between the presynaptic terminal button and the postsynaptic dendritic spine

Temporal Lobe

The part of the cerebrum in front of (anterior to) the occipital lobe and below the lateral fissure; involved in vision, auditory processing

Temporal Resolution

A term that refers to how small a unit of time can be measured; high temporal resolution means capable of resolving very small units of time; in neuroscience it describes how precisely in time a process can be measured in the brain.

Presynaptic terminal button-

The extension found at the end of the axon where information is conveyed to the next neuron.

Receptor-

The binding site for neurotransmitter.  The neurotransmitter must fit in the receptor in a lock and key fashion and when it binds, it opens an ion channel that allows ions to flow into or out of the postsynaptic cell.

Vesicle

Packages containing neurotransmitter.  They must bind to the cell membrane and dispense their neurotransmitter through a process using exocytosis (the process of having a synaptic vesicle containing various neurotransmitters fuse with the cell membrane and release the neurotransmitter into the synapse).

Spines

- Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.

Motor Neuron-

Allows us to initiate movement and behavior, ultimately allowing us to interact with the world around us.

Sensory Neuron-

Helps us receive information about the world around us.

Interneuron-

Processes the sensory input from our environment into meaningful representations, plan the appropriate behavioral response, and connect to the motor neurons to execute these behavioral plans.

Multipolar neurons 

communicate sensory and motor information in the brain. For example, their firing causes muscles in the body to contract. Multipolar neurons have one axon and many dendrites which allows them to communicate with other neurons

Bipolar Neurons

involved in sensory perception such as perception of light in the retina of the eye. They have one axon and one dendrite which help acquire and pass sensory information to various centers in the brain. 

Unipolar neurons 

structured in such a way that is ideal for relaying information forward, so they have one neurite (axon) and no dendrites. They are involved in transmission of physiological information from the body’s periphery such as communicating body temperature through the spinal cord up to the brain. 

Oligodendroglia/Schwann cells

- These cells provide myelin in the CNS and PNS.  The oligodendroglia provide myelin in the CNS where each oligodendroglia provides several “pads” of myelin around multiple nearby axons.  Schwann cells are found in the PNS and each cell wraps around one segment of the elongated nerves found in the periphery.

Microglia

They are responsible for identifying and chewing up substances that come into the brain that don’t belong there or cells that have died and need to be removed from the brain.  So, they help identify if an infectious agent comes into the brain and they help clean up waste in the brain when cells die.

Astrocytes

come from the Greek word for “star” because their shape resembles a star shape.  Astrocytes function to support neurons by maintaining chemical balances in the brain, removing waste in the brain, and performing reparative functions in the brain.  They also help in the formation of the brain-brain-barrier by creating tight junctions over the openings in the blood vessels. 

Cell membrane-

The cell membrane is composed of a lipid bilayer of fat molecules and separates the cell from the surrounding extracellular fluid.

Ion Channels

There are proteins that pass the membrane, forming ion channels that allow particular ions to pass between the intracellular and extracellular fluid.  These ions are in different concentrations inside the cell relative to the outside of the cell and these ions have different electrical charges.

Pressures acting on ions - Identify that two forces act to maintain a steady state when the cell is at rest.

3 Sodium ion and 2 Potassium ion

Diffusion

is the force on molecules to move from areas of high concentration to areas of low concentration.

Electrostatic pressure

is the force on two ions with similar charge to repel each other and the force of two ions with opposite charge to attract to another.

The giant squid axon

Hodgkin & Huxley used the giant squid's unusually large axon to measure electrical activity and discover how Na⁺ and K⁺ movement produces the action potential.

Charctheristic of Action potential

Characteristics

§All-or-nothing (once an action potential begins, it will not stop)

§Depolarized past threshold of excitation (The neuron’s membrane becomes less negative than its threshold (about −50 mV), triggering an action potential.

§Results in neurotransmitter release (Once the action potential reaches the end of the terminal buttons, neurotransmitter is released into the synapse to pass the message on to the postsynaptic cell.)

IPSP’s

are Inhibitory Post Synaptic Potentials.  These potentials result when either positively charged ions leave the cell or negatively charged ions enter the cell.

EPSP’s

are Excitatory Post Synaptic Potentials.  These potentials result when either positively charged ion’s enter the cell.

Explain Action Potential process

During an action potential, when the neuron reaches the threshold, Na⁺ channels open and sodium rushes into the cell due to diffusion and electrostatic pressure, making the inside more positive. As this happens, K⁺ channels open. At the peak, the Na⁺ channels close, and K⁺ moves out of the cell due to diffusion and electrostatic pressure. Because K⁺ continues leaving briefly, the inside becomes more negative than its normal resting state, causing a brief hyperpolarization before returning to normal

Node of Ranvier

gaps in the myelin sheath that wrap around the nerve fiber's axon

Saltatory Conduction

When the action potential skips from Node of Ranvier to the next Node of Ranvier, it is called saltatory conduction.

Enzymes

One method that is used to remove neurotransmitter from the synapse is through enzymes.  Enzymes can find neurotransmitter in the synapse and break it down before it can bind to the receptors again. Either that, or be reuptaked by the same cell that released it.

Sympathetic

Fight-or-Flight

Parasympathetic

Rest-and-Digest