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perceptual learning

Learning to recognize a particular stimulus.

stimulus-response learning

Learning to automatically make a particular response in the presence of a particular stimulus; includes classical and instrumental conditioning.

classical conditioning

When a neutral stimulus is followed several times by an unconditional stimulus that produces a defensive or appetitive response (the unconditional response), the first stimulus (now called a conditional stimulus) itself evokes the response (now called a conditional response).

Hebb rule

The hypothesis proposed by Donald Hebb that the cellular basis of learning involves strengthening of a synapse that is repeatedly active when the postsynaptic neuron fires.

instrumental conditioning

A learning procedure whereby the effects of a particular behavior in a particular situation increase (reinforce) or decrease (punish) the probability of the behavior; also called operant conditioning.

reinforcing stimulus

An appetitive stimulus that follows a particular behavior and thus makes the behavior become more frequent.

punishing stimulus

An aversive stimulus that follows a particular behavior and thus makes the behavior become less frequent.

motor learning

Learning to make a new response.

long-term potentiation

A long-term increase in the excitability of a neuron to a particular synaptic input caused by repeated high-frequency activity of that input.

hippocampal formation

A forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the hippocampus proper (Ammon's horn), dentate gyrus, and subiculum.

entorhinal cortex

A region of the limbic cortex that provides the major source of input to the hippocampal formation.

granule cell

A small, granular cell; those found in the dentate gyrus send axons to field CA3 of the hippocampus.

dentate gyrus

Part of the hippocampal formation; receives inputs from the entorhinal cortex and projects to field CA3 of the hippocampus.

field CA3

Part of the hippocampus; receives inputs from the dentate gyrus and projects to field CA1.

pyramidal cell

A category of large neurons with a pyramid shape; found in the cerebral cortex and Ammon's horn of the hippocampal formation.

field CA1

Part of the hippocampus; receives inputs from field CA3 and projects out of the hippocampal formation via the subiculum.

population EPSP

An evoked potential that represents the EPSPs of a population of neurons.

associative long-term potentiation

A long-term potentiation in which concurrent stimulation of weak and strong synapses to a given neuron strengthens the weak ones.

NMDA receptor

A specialized ionotropic glutamate receptor that controls a calcium channel that is normally blocked by Mg2+ ions; involved in long-term potentiation.

AP5

2-amino-5-phosphonopentanoate; a drug that blocks NMDA receptors.

AMPA receptor

An ionotropic glutamate receptor that controls a sodium channel; when open, produces EPSPs.

dendritic spike

An action potential that occurs in the dendrite of some types of pyramidal cells.

protein kinase

An enzyme that attaches a phosphate (PO4) to a protein and thereby causes it to change its shape.

CaM-KII

Type II calcium-calmodulin kinase, an enzyme that must be activated by calcium; may play a role in the establishment of long-term potentiation.

tyrosine kinase

A type of protein kinase that may play a role in the establishment of long-term potentiation.

nitric oxide synthase

An enzyme responsible for the production of nitric oxide.

long-term depression

A long-term decrease in the excitability of a neuron to a particular synaptic input caused by stimulation of the terminal button while the postsynaptic membrane is hyperpolarized or only slightly depolarized.

short-term memory

Memory for a stimulus that has just been perceived.

delayed matching-to-sample task

A task that requires the subject to indicate which of several stimuli has just been perceived.

transcranial magnetic stimulation

Stimulation of the cortex by the magnetic field produced by alternating current passing through a coil placed against the skull; disrupts normal activity of the affected brain region.

nucleus basalis

A nucleus of the basal forebrain that contains most of the acetylcholine-secreting neurons that send axons to the neocortex; degenerates in patients with Alzheimer's disease.

MGm

The medial division of the medial geniculate nucleus; transmits auditory and somatosensory information to the lateral nucleus of the amygdala.

extinction

With respect to classical conditioning, the reduction or elimination of a conditional response by repeatedly presenting the conditional stimulus without the unconditional stimulus.

self-stimulation

Making a response that causes the electrical stimulation of a particular region of the brain through an implanted electrode.

medial forebrain bundle/MFB

A fiber bundle that runs in a rostral-caudal direction through the basal forebrain and lateral hypothalamus; electrical stimulation of these axons is reinforcing.

mesolimbic system

A system of dopaminergic neurons whose cell bodies are located in the ventral tegmental area and whose terminal buttons are located in the nucleus accumbens, amygdala, lateral septum, hippocampus, and bed nucleus of the stria terminalis.

nucleus accumbens

A nucleus of the basal forebrain near the septum; receives dopamine-secreting terminal buttons from neurons of the ventral tegmental area and is thought to be involved in reinforcement and attention.

mesocortical system

A system of dopaminergic neurons whose cell bodies are located in the ventral tegmental area and whose terminal buttons are located in the cerebral cortex and hippocampus.

conditioned reinforcer

A previously neutral stimulus that has been paired with an appetitive stimulus, which then itself becomes capable, of reinforcing a response.

conditioned punisher

A previously neutral stimulus that has been followed by an aversive stimulus, which then itself becomes capable of punishing a response.

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anterograde amnesia

Amnesia for events that occur after some disturbance to the brain, such as head injury or certain degenerative brain diseases.

retrograde amnesia

Amnesia for events that preceded some disturbance to the brain, such as a head injury or electroconvulsive shock.

Korsakoff's syndrome

Permanent anterograde amnesia caused by brain damage resulting from chronic alcoholism or malnutrition.

confabulation

The reporting of memories of events that did not take place without the intention to deceive; seen in people with Korsakoff's syndrome.

short-term memory

Immediate memory for events, which may or may not be consolidated into long-term memory.

long-term memory

Relatively stable memory of events that occurred in the more distant past, as opposed to short-term memory.

consolidation

The process by which short-term memories are converted into long-term memories.

priming

A phenomenon in which exposure to a particular stimulus automatically facilitates perception of that stimulus or related stimuli.

declarative memory

Memory that can be verbally expressed, such as memory for events in a person's past.

nondeclarative memory

Memory whose formation does not depend on the hippocampal formation; a collective term for perceptual, stimulus-response, and motor memory.

perirhinal cortex

A region of limbic cortex adjacent to the hippocampal formation that, along with the parahippocampal cortex, relays information between the entorhinal cortex and other regions of the brain.

parahippocampal cortex

A region of limbic cortex adjacent to the hippocampal formation that, along with the perirhinal cortex, relays information between the entorhinal cortex and other regions of the brain.

working memory

Memory of what has just been perceived and what is currently being thought about; consists of new information and related information that has recently been retrieved from long-term memory.

reference memory

A form of long-term memory of stable conditions and contingencies in the environment; includes perceptual memory and stimulus-response memory.

place cells

A neuron of the hippocampus that becomes active when the animal is in a particular location in the environment.

theta rhythm

EEG activity of 5-8 Hz; an important indication of the physiological state of the hippocampus.

ventral angular bundle

The bundle of axons that conveys information from the hippocampal formation to the basolateral amygdala.

recurrent collateral

A branch of an axon leaving a particular region of the brain that turns back and forms synapses with neurons near the one that gives rise to it.