Glossary
- Action potential
- The “all or nothing” electrical signal sent by a neuron.
It is initiated in the cell body and travels down the axon
of the neuron to the next neuron. It
is created by the flow of ions across the neurons membrane through small
pores that open on cue. Such a
change in the concentration of ions leads to the separation of charge, also
known as “potential.”
- Adenylyl cyclase
- A membrane bound enzyme that catalyzes
the formation of cyclic AMP (adenosine 5’ monophosphate) from ATP
(adenosine 5’-triphosphate).
- Agonist
- A drug that increases or facilitates a neurotransmitter or its
receptor.
- Amygdala
- An area of the brain located near the hippocampus
in the temporal lobe that has strong links with emotion and memory.
- Androgynous
- Neither specifically feminine nor masculine, suitable to or for either
sex. In this case refers to the
fact that naloxone has the same effect on the dopamine system for men and
women.
- Anesthesic
- Anything that produces lack of
tactile perception.
- Antagonist
- A drug that interferes with the action of a neurotransmitter
or its receptor.
- Anterograde memory interference
- Refers to difficulty with remembering things that happen after an event.
In this case it refers to the difficulty of remembering things that
occurred after the treatment.
- Antipsychotics
- A class of pharmaceutical drugs
that have been shown to negate psychotic symptoms in patients with disrupted
thought patterns, hallucinations or delusions.
- Assertion training
- In many cases the mentally ill are socially withdrawn and unable to lead a
fulfilling life. Assertion
training teaches them not to be afraid of social situations by teaching them
how to better interact and fit-in in interpersonal situations.
- Autoreceptors
- A receptor located on the
pre-synaptic membrane that is able to exert its effects on the pre-synaptic cell
in response to neurotransmitter release. These
receptors most often modulate the synaptic transmission (i.e. signals between
neurons) in progress.
- Axon
- The long thin extension of a neuron that is
capable of transmitting electrical impulses over long distances to other cells.
Adapted from Carlson's Physiology of Behavior.
- Basal ganglia
- Masses of gray matter (i.e. cell
bodies) underneath the cortex of the brain that are important to such things as
movement. It includes the
substantia nigra, putamen, caudate nucleus, and globus pallidus.
Adapted from Kandel's Principles of Neural Science.
- Behavioral
- Pertaining to the actions of a person or animal.
In this case behavioral specifically refers to the actions that might
indicate the effectiveness of certain treatment.
- Brainstem
- This is the area of the central
nervous system that is best described anatomically as the segue between the
brain and the spinal cord, and is divided into three sections: the midbrain,
pons, and medulla.
Adapted from Carlson's Physiology of Behavior.
- cAMP
- Cyclic AMP is a compound produced in the
cytoplasm of a cell (fluid inside the cell) that can activate proteins or genes.
By activating certain key proteins or genes, cAMP can thus change the
“behavior” of the cell. Because cAMP acts as a messenger between the receptor and the
target gene or protein, it is known as a “second messenger”.
- Caudal
- This is a descriptive term used to
indicate direction within the nervous system.
It is derived from the Latin word for “tail” and thus indicates a
direction towards the “tail”. Its
use is frequently reserved for descriptions of the spinal cord, while
“posterior” is used in its place for describing locations/ directions within
the brain.
Adapted from Carlson's Physiology of Behavior.
- Caudate nucleus
- This is a group of nerve cell
bodies (as indicated by the term ‘nucleus’) found deep within the brain, and
is part of the basal ganglia. It
is somewhat hook shaped, running parallel to the lateral ventricles and then
hooking under itself in the caudal (posterior) area of the brain.
The lateral ventricles can be clearly seen in coronal sections (see
diagram below) of the brain using an MRI. They
appear as two twin “holes” in the very center, with the caudate nucleus just
next to them.
Adapted from Haines' Neuroanatomy.
- Cell bodies
- This descriptive term is most
helpful in the anatomy of cells within the nervous system. Most cells are relatively compact with few or no extensions.
Because neurons can stretch between distant locations, it is important to
distinguish between these long extensions (axons and dendrites) and the
main body of the cell which contains many crucial organelles, as well as the DNA
for the cell. See picture under axon
for a better understanding.
- Cognitive
- Pertaining to the act or process of knowing including both
awareness and judgment or a product of this act.
- Efficacy
- Literally, the power to produce an
effect. In this case it is the
power of a drug to reduce symptoms.
- Endogenous
- Refers to compounds produced or
synthesized within an organism.
- Endorphin-antagonist
- An antagonist in the neurological sense in a chemical that is similar to
another chemical and for that reason is able to fill the place that the
chemical it is similar to would have taken on a nerve but is not similar
enough for the nerve to recognize it as that chemical and make use of it for
neural communication.
- Exogenous
- Refers to compounds
that are introduced into an organism from an outside source.
- Hippocampus
- A prominent structure found within
the temporal lobe. It has a very
distinctive “swirl” pattern when viewed with an MRI machine, and is
responsible for the formation of memories, and the processing of new memories.
- Histamine
- A molecule released into the
environment by damaged or dying cells. It
is a key component of the inflammatory response of the immune system to an
unwanted or foreign entity within the body, hence its involvement in allergic
reactions.
- Hyper
- A prefix used to indicate “excess” or
“above”
- Hypo
- A prefix used to indicate “less than
normal” or “under”
- Inhibitory
- In reference to the nervous system,
the term “inhibitory” is used to describe any influence (whether it is a neurotransmitter,
electrical stimulus, or neural connection) that will prevent a neuron from
firing its action potential, or make it harder for that neuron to fire its action
potential. This term can also
be used to refer to the effects on a whole system or group of neurons that act
together.
- Internalization
- Literally, to incorporate (as values or patterns of culture) within
the self as conscious or subconscious guiding principles through learning or
socialization. This refers to
designating the voices as internal mechanisms as opposed to external
stimuli.
- Ligand
- In this context, ligand refers to any
compound that can act on a receptor. It
may be endogenous, or exogenous in origin.
- Limbic system
- This system is primarily
responsible for such behavioral responses as feeding behavior, “fight or
flight” responses, aggression, sexual responses, emotional responses and
emotional memory. It is composed of
many structures throughout the brain, including the hippocampus, amygdala
and the singulate gyrus, which can be seen in diagram under brainstem,
above.
- Mast cells
- A cell of the immune system found
throughout the body. They contain
small packets called “granules” that they release following interaction with
another cell, which triggers excitatory autonomic events (“fight” response)
as well as inflammatory reactions such as swelling.
- Midbrain
- This is an area of the brainstem
that is the closest to the brain. It
contains all of the ascending and descending axons from the brain and spinal
cord, as well as key nuclei involved in other aspects of behavior.
See picture under brainstem for a better understanding.
- Efficacy
- Literally, the power to produce an
effect. In this case it is the
power of a drug to reduce symptoms.
- Neurochemistry
- Chemical
processes and phenomena related to the nervous system.
- Neurological
- Literally, pertaining to the scientific
study of the nervous system especially in respect to its structure,
functions, and abnormalities. Related
to the nervous system.
- Neurotransmitter
- A natural
chemical released at the end of an axon (terminal bouton) that acts on another
neuron, either exciting that neuron, or inhibiting it.
- Nucleus accumbens
- An area of the ventral
striatum (i.e. near the “base” of the caudate nucleus and putamen)
with strong connections to the limbic system. This receives dopaminergic connections from the ventral
tegmental area in the mesolimbic system (see Overview of Dopaminergic
Pathways).
- Orientation
- In this case, orientation refers to the nature of the hallucinations.
Whether they be auditory, visual or other.
- Parkinson’s Disease
- A disease associated with
the degradation of the substantia nigra, a darkly pigmented area of the midbrain
that houses many dopamine producing neurons.
The resulting symptoms are severe motor deficits.
Patients suffering from Parkinson’s Disease exhibit uncontrollable
shaking, especially of the hands, and have great problems initiating movement so
even simple actions like walking are extremely difficult.
- PET scan
- Short for “Positron Emission
Tomography,” a PET scan is a great tool for viewing the dynamic (changing)
aspects of brain activity. A
patient is injected with a radioactive isotope which emits a signature gamma
ray. When different areas of the
brain are being used, blood flow to these areas will increase, thus increasing
the concentration of the radioactive isotope in these areas.
This allows researchers to see what parts of the brain are “active”
during different behavioral or thought processes.
- Placebo
- An inert or innocuous substance used especially in controlled experiments
testing the efficacy of another substance (as a drug).
- Positive symptoms
- The symptoms of schizophrenia
are separated into two categories, positive and negative. This web page is focusing only on the positive symptoms which
include such visible abnormalities as thought disorders, delusions, and
hallucinations. These are all the
classic, hallmark symptoms associated with the disease.
- Putamen
- An area of the basal ganglia, and the
subcomponent of the basal ganglia, the striatum. (See striatum or basal ganglia)
- Reinforcement
- Reward of some kind.
In this case the patients are reinforced socially with smiles and
extra attention when they vocalize less in response to the hallucinations
they experience.
- Relapse
- Relapse refers to a state of returned symptoms.
Literally, a recurrence of symptoms of a disease after a period of
improvement.
- Retrograde memory interference
- Refers to difficulty with remembering things that happen before an event.
In this case it refers to the difficulty of remembering things that
occurred after the before the treatment.
- Reuptake
- Following release of a neurotransmitter
into the synaptic cleft, there are three things that can happen to the
“excess” neurotransmitter that is not immediately taken up by the
receptors because they are all “full.”
If the neurotransmitter does not diffuse away, or breakdown, then
mechanisms often exist for reuptake, a process in which the neurotransmitter
is repackaged into vesicles and taken back into the cell to be released later.
- Rostral
- This is a descriptive
term used to indicate direction within the nervous system. It is derived from the Latin word for “head” and thus
indicates a direction towards the “head”.
Its use is frequently reserved for descriptions of the spinal cord, while
“anterior” is used in its place for describing locations/ directions within
the brain. For a better
understanding, see diagram under caudal.
- Second messenger
- A compound that acts as a
“messenger” between an activated receptor, and the receptor’s targets
within the cytoplasm. See cAMP.
- Seven membrane-spanning G-protein linked receptor
- This
is a type of receptor whose long protein chain is sort of “stitched” into
the membrane of a cell so that is crosses the membrane seven times.
This means that one end of this “protein thread” will face the
external environment, while the other will face the internal environment.
When the appropriate molecule binds to the external end, it causes the
internal end (or “cytoplasmic tail”) to change its structure slightly. This change in structure causes the internal end to detach
from the G-protein it normally attaches to, thus allowing the G-protein to
become active. Once active, the
G-protein breaks into two parts which can then activate other proteins,
eventually leading to an internal change for the cell, such as turning on or off
a gene. This is a type of second
messenger system.
Unactivated. . .
Activated. . . .
- Adapted from Essential Cell Biology.
-
- Striatum
- The area of the basal ganglia composed
of the putamen and the caudate nucleus. The
putamen and caudate nucleus are only next to each other in the
front (anterior) or the brain. As
you continue in the caudal direction, they separate.
- Synapse
- The junction between two neurons.
See picture under axon.
- Synaptic cleft
- Because neurons do not actually
come into physical contact with each other, at the synapse there is a
tiny space between each neuron and this space is known as the synaptic cleft.
See picture under axon.
- Tardive-dyskenisia
- In this case it refers to an unconscious facial tic or spasm caused by
nerves misfiring.
- Titrate
- Adjust. In this case adjusting the dosage of the patient to a level
that best suits them.
- Ventral tegmental area
- An area of the midbrain
that sends dopaminergic projections to the frontal cortex or the nucleus
accumbens.
- Vesicle
- A tiny “package” made out of
membrane that contains concentrated “doses” of neurotransmitter, and
localized to the end of the axon (the “terminal bouton”).
When an electrical signal passes down the axon this is a trigger for the
packages of membrane to merge with the pre-existing cell membrane, thus opening
(like soap bubbles that touch) and allowing the neurotransmitter to spill
into the synaptic cleft. For
better understanding, see picture under axon.
- Vesicular storage
- The process of loading neurotransmitter
into vesicles.
