Neuro Final

Chapter 5: Hormones and the Brain, Chapter 17: Learning and Memory

Learning

The process of acquiring new and relatively enduring information, behavior patterns, or abilities, characterized by modifications of behavior as a result of practice, study, or experience.

Memory

1. The ability to retain information, based on the mental process of learning or encoding, retention across some interval of time, and retrieval or reactivation of the information
2. The specific information that is stored in the brain.

Amnesia

Severe impairment of memory.

Retrograde amnesia

Difficult in retrieving memories formed before the onset of amnesia.

Patient H.M.

A person who, because of damage to medial temporal lobe structures, was unable to encode new declarative memories. Upon his death we elearned his name was Henry Molaison.

Anterograde amnesia

The inability to form new memories beginning with the onset of a disorder.

Hippocampus

A medial temporal lobe structure important for learning, memory, and spatial navigation.

Declarative memory

A memory that can be stated or described. That which was can declare to others.

Nondeclarative memory

Also called procedural memory. A memory that is shown by performance rather than by conscious recollection. Think performance rather than recollection.

Delayed non-matching-to-sample task

A test in which, on each trial, the participant must select the stimulus that was not seen previously.

Patient N.A.

A person who is unable to encode new declarative memories, because of damage to the dorsal thalamus and the mammillary bodies.

Mammillary bodies

One of a pair of nuclei at the base of the brain that connect to the hippocampus and play a role in memory.

Korsakoff's syndrome

A memory disorder, related to a thiamine deficiency, that is generally associated with chronic alcoholism.

Confabulate

To fill in a gap in memory with a falsification. It often occurs in Korsakoff's syndrome.

Patient K.C.

A person who sustained damage to the cortex that rendered him unable to retrieve autobiographical memories. Upon his death we learned that his name was Kent Cochran.

Episodic memory

Memory of a particular incident or a particular time and place.

Semantic memory

Generalized memory - for instance, knowing the meaning of a word without knowing where or when you learned that word.

Skill learning

Learning to perform a task that requires motor coordination

Priming

Also called repetition priming. The phenomenon by which exposure to a stimulus facilitates subsequent responses to the same or a similar stimulus.

Associative learning

A type of learning in which an association is formed between two stimuli or between a stimulus and a response. It includes both classical and operant conditioning.

Operant conditioning

Also called instrumental conditioning. A form of associative learning in which the likelihood that an act (instrumental response) will be performed depends on the consequences (reinforcing stimuli) that follow it.

Classical conditioning

Also called Pavlovian conditioning. A type of associative learning in which an originally neutral (conditioned) stimulus acquires the power to elicit the response normally elicited by another (unconditioned) stimulus after the two stimuli are paired. A response elicited by the unconditioned stimulus (US) is called an unconditioned response (UR); a response elicited by the conditioned stimulus (CS) alone is called a conditioned response (CR).

Cognitive Map

A mental representation of a spatial relationship.

Place cells

A neuron within the hippocampus that selectively fires when the animal is in a particular location.

Grid cells

A neuron that selectively fires when an animal crosses the intersection points of an abstract grid map of the local environment.

Border cells

A neuron that selectively fires when an animal arrives at the perimeter of a local spatial cognitive map.

Sensory buffer

An element of the type of memory that stores the sensory impression of a scene.

Short-term memories (STMs)

A form of memory that usually lasts only for seconds, or as long as rehearsal continues, especially while being used during performance of a task.

Working memory

A type of short-term memory that holds a limited amount of information available for ready access during performance of a task.

Prefrontal cortex

The most anterior portion of the frontal lobe.

Intermediate-term memory

A form of memory that lasts longer than short-term memory but not as long as long-term memory.

Long-term memories (LTMs)

An enduring form of memory that lasts days, weeks, months, or years and has a very large capacity.

Encoding

A stage of memory formation in which the information entering sensory channels is passed into short-term memory.

Consolidation

A stage of memory formation in which information in short-term or intermediate-term memory is transferred to long-term memory.

Engrams

The physical basis of a memory in the brain. It is sometimes referred to as a memory trace on the assumption that it involves changes in a neural circuit rather than a single neuron.

Retrieval

A process in memory during which a stored memory is used by an organism.

Reconsolidation

The process by which a retrieved memory may be strengthened or altered before being returned to long-term memory.

Posttraumatic stress disorder (PTSD)

Formerly called combat fatigue, war neurosis, or shell shock. A disorder in which memories of an unpleasant episode repeatedly plague the victim.

Neuroplasticity

Also called neural plasticity. The ability of the nervous system to change in response to experience or the environment.

Standard condition (SC)

The usual environment for laboratory rodents, with a few animals in a cage and adequate food and water but no complex stimulation.

Impoverished condition (IC)

Also called isolated condition. A condition in which laboratory rodents are housed singly in a small cage without complex stimuli.

Enriched condition (EC)

Also called complex environment. A condition in which laboratory rodents are group-housed with a wide variety of stimulus objects.

Nonassociative learning

A type of learning in which presentation of a particular stimulus alters the strength or probability of a response according to the strength and temporals spacing of that stimulus. It includes habituation and sensitization.

Habituation

A form of nonassociative learning in which an organism becomes less responsive following repeated presentations of a stimulus.

Dishabituation

The restoration of response amplitude following habituation.

Sensitization

1. A process in which the body shows an enhanced response to a given drug after repeated doses.
2. A form of nonassociative learning in which an organism becomes more responsive to most stimuli after being exposed to unusually strong or painful stimulation.

Cell assembly

A large group of cells that tend to be active at the same time because they have been activated simultaneously or in close succession in the past.

Hebbian synapses

A synapse that is strengthened when it successfully drives the postsynaptic cell.

Tetanus

An intense volley of action potentials.

Long-term potentiation (LTP)

A stable and enduring increase in the effectiveness of synapses following repeated strong stimulation.

Dentate gyrus

A strip of gray matter in the hippocampal formation.

NMDA receptor

A glutamate receptor that also binds the glutamate agonist NMDA (N-methyl-D-aspartate) and that is both ligand-gated and voltage-sensitive.

AMPA receptors

A glutamate receptor that also binds the glutamate agonist AMPA.

Protein kinase

An enzyme that adds phosphate groups (PO4) to protein molecules, altering the protein's function.

Retrograde messenger

Transmitter that is released by the postsynaptic region, travels back across the synapse, and alters the functioning of the presynaptic neuron.

CREB

Cyclic AMP responsive element - binding protein, which binds the promoter region of several genes involved in neural plasticity when activated by cAMP.

Conditional knockout

A gene that can be selectively deactivated in specific tissues and/or at a specific stage of development.

Nootropics

A class of drugs that enhance cognitive function.

Hormones

A chemical secreted by cells that is conveyed by the bloodstream and regulates target organs or tissues.

Endocrine glands

A gland that secretes hormones into the bloodstream to act on distant targets.

Exocrine glands

A gland whose secretions exit the body via ducts.

Castration

Removal of the gonads, usually the testes.

Endocrine

Referring to glands that release chemicals to the interior of the body. These glands secrete the principal hormones.

Autocrine

Referring to a signal that is secreted by a cell into its environment and that feeds back to the same cell.

Paracrine

Referring to cellular communication in which a chemical signal diffuses to nearby target cells through the extracellular space.

Allomones

A chemical signal that is released outside the body by one species and affects the behavior of other species.

Neuroendocrine cells

Also called neurosecretory cell. A neuron that releases hormones into local or systemic circulation.

Neuropeptides

Also called peptide neurotransmitter. A peptide that is used by neurons for signaling.

Neuromodulators

A substance that influences the activity of synaptic transmitters.

Peptide hormone

A class of hormones, each of which consists of a string of amino acids. If the string of amino acids is long enough, it may be called a protein hormone.

Amine hormones

Also called monoamine hormones. A class of hormones, each composed of a single amino acid that has been modified into a related molecule, such as melatonin or epinephrine.

Steroid hormones

A class of hormones, each of which is composed of four interconnected rings of carbon atoms.

G protein-coupled receptors (GPCRs)

A large family of cell-membrane-spanning receptors that, when activated extracellularly, use G proteins on their intracellular surface to affect the receiving cell.

Second messenger

A slow-acting substance in a target cell that amplifies the effects of synaptic or hormonal activity and regulates activity within the target cell.

Cyclic adenosine monophosphate (cyclic AMP, or cAMP)

A second messenger activated in many target cells in response to synaptic or hormonal stimulation.

Inositol triphosphate (IP3)

A member of a class of second-messenger compounds (phosphoinositides) common in postsynaptic cells.

Diacylglycerol (DAG)

A common second-messenger compound in postsynaptic cells.

Transcription factor

A substance that binds to recognition sites on DNA and alters the rate of expression of particular genes.

Steroid receptor cofactors

Proteins that affect the cell's response when a steroid hormone binds its receptor.

Autoradiography

A histological technique that shows the distribution of radioactive chemicals in tissues.

Nongenomic effect

An effect of a steroid hormone that is not mediated by direct changes in gene expression.

Neurosteroids

Steroid molecules produced within the brain that affect neurons.

Aromatase

An enzyme that converts some androgens into estrogens.

Negative feedback

The process whereby a system monitors its own output and reduces its activity when a set point is reached.

Tropic hormones

A class of anterior pituitary hormones that affect the secretion of other endocrine glands.

Releasing hormones

A class of hormones, produced in the hypothalamus, that traverse the hypothalamic-pituitary portal system to control the pituitary's release of tropic hormones.

Pituitary gland

Also called hypophysis. A small, complex endocrine gland located in a socket at the base of the skull.

Anterior pituitary

Also called adenohypophysis. The front division of the pituitary gland. It secretes tropic hormones.

Posterior pituitary

Also called neurohypophysis. The rear division of the pituitary gland.

Pituitary stalk

Also called infundibulum. A thin piece of tissue that connects the pituitary gland to the hypothalamus.

Oxytocin

A hormone, released from the posterior pituitary, that triggers milk letdown in the nursing female.

Arginine vasopressin (AVP)

Also called vasopressin or antidiuretic hormone (ADH). A peptide hormone from the posterior pituitary that promotes water conservation.

Supraoptic nucleus

A hypothalamic nucleus containing neuroendocrine cells that send axons to the posterior pituitary to release oxytocin or vasopressin.

Paraventricular nucleus (PVN)

A nucleus of the hypothalamus implicated in the release of oxytocin and vasopressin and in the control of feeding and other behaviors.

Milk letdown reflex

The reflexive release of milk in response to suckling or to stimuli associated with suckling.

Median eminense

Midline feature on the base of the brain marking the point at which the pituitary stalk exits the hypothalamus to connect to the pituitary. It contains elements of the hypophyseal portal system.

Hypophyseal portal system

Also called pituitary portal system. A system of capillaries spanning between the neurosecretory cells of the hypothalamus and the secretory tissue of the anterior pituitary.

Adrenocorticotropic (ACTH)

A tropic hormone secreted by the anterior pituitary gland that controls the production and release of hormones of the adrenal cortex.

Thyroid-stimulating hormone (TSH)

A tropic hormone, released by the anterior pituitary gland, that signals the thyroid gland to secrete its hormones.

Gonadotropin

Any anterior pituitary hormone that selectively stimulates the gonads to produce steroids and gametes.