Glossary

A

Aggregate Field
The notion that the whole brain participates in behavior.
Amygdala
A collection of nuclei at the base of the temporal lobe, part of the limbic system. Plays a role in several emotional behaviors such as agression and sexual behavior.
Anterior Cerebral Artery
One of the three primary cerebral arteries. Provides blood supply primarily to the frontal and parietal lobes.
Anterior Commissure
A forebrain commissure that provides communication between structures within the temporal lobes.
Autoreceptor
A receptor molecule located in the presynaptic neuron's axon terminal. It is thought to play a role in providing feedback to the presynaptic neuron and play a role in modulating synaptic activity.
Axon
Part of the neuron that carries the neural impulse away from the soma toward the target of the neuron. This part of the neuron carries action potentials.
Axon Hillock
The portion of the axon where the axon leaves the soma. It is here that spatial and temporal summation occur and the action potential begins.
Axon Terminal
The ending of the axon that connects to the neural target. It contains the neural transmitters to be released.

B

Broca's Area
A brain center associated with the motor control of speech and usually located in the left side of the frontal lobe.

C

Commissure
any fiber tract that connects between structures on the two sides of the central nervous system.
Concentration
The number of molecules of a substance per unit volume.
Concentration Gradient
The difference in level of concentration between two areas. There is a tendency for molecules to flow, by chance movements, from regions of high concentrations to low concentrations.
Corpus Callosum
The largest commissure. Provides communication across the midline for most forebrain structures.
Current
Electrical energy flowing, that is, the kinetic energy form of electricity.
Cytoarchitectonics
Cellular architecture: how cells differs between brain regions.

D

Degradation
The process by which neurotransmitter molecules are broken down into inactive metabolites.
Dendrite
Processes of the neuron that receives information from other neurons. That is these structures have places with receptors and are able to form synapses with incoming neurons.
Dendritic Stalk
The thickening of the dendrite where it forms synapses.
Depolarization Phase of the Action Potential
The initial portion of the action potential where the voltage sweeps from the resting potential past the neutral voltage to where the inside of the axon is now positive relative to the outside of the axon.
Diaschisis
The idea that damage to one part of the brain can create problems for another part of the brain.
Diffusion
Diffusion is the effect that the random movement of molecules have that causes the movement of molecules from a region of high concentration to low concentration. Diffusion will stop (that is the change in the relative levels of concentration) when the concentration of the substance in solution is equal at all points.

E

Electricity
Part of the electromagnetic force carried by the movement of charged particles.
Energy
The capacity to do work. What is meant here is that energy makes things happen or change. Without energy, all things stay in their same state.
Engram
A hypothetical change in neural tissue postulated in order to account for persistence of memory.

H

Hippocampus
A structure in the forebrain, part of the limbic system. Seems to be involved in spatial and memory functions.

I

Inferior Colliculus
The lower pair of two pairs of bumbs on the posterior side of the midbrain. These structures relay auditory information from brainstem auditory nuclei to the Medial Geniculate Nucleus.
Internal Carotid Artery
One of the primary arteries that supplies blood to the brain.
Ion
An electrically charged particle. Ions can be positive (e.g. Na+) or negative (e.g. Cl-). Like charges repel or push each other away, and opposite charges attract or draw each other.
Ionotropic
A type of synpatic receptor. The receptor and effector functions of gating are carried out by different domains of a single macromolecule. Compare metabotropic.

K

Kinetic Energy
Energy being expended in performing work.

L

Lateral Ventricles
The two largest cavities, in the forebrain, where the cerebral spinal fluid is produced.

M

Massa Intermedia
A fiber tract that connects the two thalami.
Meninx (pl. meninges)
A membrane, especially one of the three membranes enclosing the brain and spinal cord in vertebrates.
Metabotropic
A type of synpatic receptor. The receptor and effector functions of gating are carried out by separate molecules. Compare ionotropic.
Modulatory Synaptic Actions
Generally used in reference to metabotropic receptors: Actions which are not sufficient to cause cells to fire action potentials. Instead, they influence the electrophysiological properties of the cell, such as changes in resting potentials, threshold potentials, or action potential duration.
Myelin
A sheath of fatty tissue that covers most axons on the nervous system. It serves to speed conduction my limiting true action potentials to the gaps in the sheath. Under the myelin the neural impulse moves at the speed of light. The layer is formed by Schwann Cells in the periphereral nervous system and Oligodendrocytes in the central nervous system.

N

Node of Ranvier
The gap in the myelin sheath where the action potential occurs during saltatory conduction.
Nucleus
The structure in the soma of the neuron that contains the chromosomes.

O

Occipital Horn
The most posterior porjections of the Lateral Ventricles.
Optic Chiasm
Part of the pathways that carry the visual information from the retina in the eyes to the lateral geniculat nucleus. In particular at this location, the axons carrying information from the nasal half of each retina cross, that is decussate, which the axons from the temporal retina do not decussate.
Optic Nerve
The portion of the axons that originate in the ganglion cell layer of the retina that travels from the retina to the optic chiasm.

P

Phrenology
The study of the conformation of the skull based on the belief that it is indicative of mental faculties and character.
Potential Energy
Energy that is available to do work.
Presynaptic Neuron
The neuron which releases the neurotransmitters into the synapse. The axon terminal is part of the presynaptic neuron.
Posterior Cerebral Artery
One of the three primary cerebral arteries. Provides blood supply primarily to the temporal and occipital lobes.
Posterior Communicating Artery
Part of the cerebral circulation, more particulary, part of the Circle of Willis that allows blood from any of the supply arteries in the neck to provide blood to all of the cerebral arteries.
Postsynaptic Neuron
The neuron that which receives the neurotransmitters released by the presynaptic neuron. It is in most synapses a dendrite or soma.

R

Receptor
A molecule in the postsynpatic neuron's membrane to which the neurotransmitters bind, which then directly or indirectly will alter the membrane potential by opening or closing ion channels.
Resting Potential
The voltage that is across the membrane of an axon when that portion of the action is not conducting an action potential but is in a state ready to conduction an action potential.
Reuptake
The process by which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity.

S

Soma
The part of the neuron where the nucleus is found. Most of the protein production and energy storage is performed at this point in the cell.
Sulcus
A groove on the surface of the brain.
Superior Colliculus
The top pair of the two pair of bump on the posterior surface of the midbrain. Plays a role in vision, perhaps a part of the role vision plays in orienting us to the world, and eye movements.
Sylvian Acqueduct
A connecting path for cerebral spinal fluid between the III and IV ventricles.
Sylvian Fissure
The deep groove or sulcus that marks the boundary between the frontal lobe and temporal lobe.
Synaptic Cleft
The space between the two neurons that form the synapse.
Synaptic Vesicle
A membrane structure in the axon terminal that contains the neurotransmitters until they are released.

V

Vasculature
The arrangement of blood vessels in an organ or part.
Voltage
A difference in electrical charge between two locations. One region is more positive than the other. This situation represents the potential energy for electricity.