Biological Bases of Learning and Memory

Practice flashcards covering the biological mechanisms of memory, types of amnesia, the case of HM, and the neuronal processes of Long-Term Potentiation (LTP).

Henry Molaison (HM)

A patient who underwent a bilateral medial temporal lobectomy in 1953 to control seizures, resulting in profound anterograde amnesia while retaining memories from before the surgery.

Anterograde Amnesia

The inability to later remember events that occur after brain damage has occurred.

Retrograde Amnesia

The inability to remember events that took place prior to the occurrence of brain damage.

Sensory Memory

A brief period of time ranging from fractions of a second to a few seconds where the initial sensation of environmental stimuli is remembered.

Short-Term Memory

A limited capacity memory store containing meaningful information from sensory memory that lasts for seconds to minutes and can be maintained through rehearsal.

Long-Term Memory

A relatively permanent memory store containing consolidated information that can last for hours, days, or decades and is strengthened by retrieval.

Declarative Memory

Also known as explicit memory, it includes memories of events (episodic), facts (semantic), and spatial relationships that can be consciously recalled and talked about.

Nondeclarative Memory

Also known as implicit memory, it operates automatically to control motor behaviors and skills, such as riding a bike, which a person may not be consciously aware of learning.

Episodic Memory

A type of declarative memory involving specific events and experiences tied to a context.

Semantic Memory

A type of declarative memory involving factual knowledge and concepts.

Hebb's Law

The principle proposed in 1949 that if a synapse is repeatedly active at the same time a postsynaptic neuron fires, the structure or chemistry of the synapse will change to strengthen it.

Long-Term Potentiation (LTP)

A long-term increase in the excitability of a neuron to a particular synaptic input, evidenced by an increase in the population excitatory postsynaptic potential ($EPSP$).

NMDA Receptor

A neurotransmitter- and voltage-dependent ion channel that is blocked by magnesium ($Mg^{2+}$) at resting potential and allows calcium ($Ca^{2+}$) to enter when the membrane is depolarized and glutamate is present.

AMPA Receptor

A glutamate receptor that, when activated, allows sodium ($Na^+$) into the neuron to cause depolarization; an increased number of these in the postsynaptic membrane strengthens the synapse during LTP.

Entorhinal Cortex

The part of the brain that controls egocentric guidance, telling an individual which direction to go.

Allocentric Memory

Navigation and memory based on where one is in relation to other things in the environment, which is impaired by damage to the right hippocampus.

Egocentric Memory

Spatial guidance and navigation based on an individual's own perspective rather than external relationships.

Morris Water Maze

A behavioral task used to study spatial learning in rats, involving a hidden platform in a pool of water.

Consolidation

The process by which the hippocampus modifies and links sensory and motor information together to store episodic memories in long-term memory.

Excitatory Postsynaptic Potential (EPSP)

The depolarization of the postsynaptic membrane, which in the glutamate system is increased to help establish conditioned responses during LTP.