Learning and Memory

Henry Molaison

old memories intact

could not retain new material after surgery

retrograde amnesia

loss of memories formed before onset of amnesia

anterograde amnesia

inability to form memories after onset of a disorder

MRI of H.M’s brain: amygdala and most of the _________ and cortex from both temporal lobes were removed

hippocampus

Surgical patients with similar surgery but an intact hippocampus showed no ______ ________

memory impairment

experiments with monkeys provided concrete evidence that H.M;s memory deficit was caused by loss of the ______ _______ _______, including the hippocampus

medial temporal lobe

Parahippocampal gyrus

hippocampus

perirhinal cortex

entorhinal cortex

delayed matching-to-sample task

test of object recognition memory that requires monkeys to declare what they remember

declarative

things you know that you can tell others

nondeclarative

things you know that you can show by doing

Patient N.A

suffered damage to dorsomedial thalamus and mammillary bodies (caused amnesia)

N.A had short-term memory like H.M; however…

cannot form declarative LTMs

Similarity to N.A and H.M in symptoms paired with damage to different regions suggests a ______ _____ _______

larger memory network

Mammillary bodies may serve as processing system connecting the medial temporal lobes to _______ and other cortical sites

thalamus

Damage to the ______ ______ can cause amnesia

medial diencephalon

Korsakoff’s syndrome

degenerative disease

due to lack of thiamine

patients often don’t recognize memory impairment

confabulate

fill gap in memory with fascination

Treatment with _____ can reduce further damage for Korsakoff’s syndrome

thiamine

memory impairment caused by damage to mammillary bodies, dorsomedial thalamus, and _____ ______

frontal cortex

Patient K.C

suffered extensive damage to left frontoparietal cortex and right parieto-occipital cerebral cortex and from dramatic bilateral shrinkage of hippocampus and adjacent cortex

declarative memory

semantic and episodic memory

semantic memory

generalized declarative memory

episodic memory

detailed autobiographical memory

Current model of declarative memory formation

1. sensory processing in cortex

2. parahippocampal, entorhinal, perirhinal cortex

3. hippocampus

4. medal diencephalon (mammillary bodies

5. declarative memory storage in cortex

Damage to either medial temporal lobe or medial diencephalon/mammillary bodies will prevent formation of any new _________ ________ without loss of previously formed memories

declarative memories

nondeclarative memory

skill and cognitive skill learning

priming

associative learning

nonassociative learning

operant conditioning

spatial learning

skill learning

learning to perform a challenging task through repetition

types of skill learning

sensorimotor, perceptual, and cognitive (impaired by damage to basal ganglia)

priming

change in stimulus processing due to prior exposure to stimulus

Which patient was priming perceived in

Patient H.M

perceptual priming

visual form of words

conceptual priming

meaning

different types of priming are related to reduced activity in different ______ ______

cortical areas

parts of brain used in episodic memory

medial temporal lobe

neocortex

parts of brain used in semantic memory

medial temporal lobe

neocortex

parts of brain used in skill learning (procedural)

striatum, motor cortex, cerebellum

parts of brain used in priming

neocortex

associative learning

association between two stimuli or between a stimulus and response

classical conditioning

neutral stimulus, repeatedly paired with a stimulus that elicits a response, begins to elicit the response of stimulus when presented alone

nonassociative learning

changes in behavior toward a stimulus without associating it with a specific reward or punishment

parts of brain used in classical conditioning

amygdala

cerebellum

parts of brain used in nonassociative learning

reflex pathaways

operant conditioning

association made between behavior and consequences of behavior (reinforcement and punishment)

Neurons in reward circuit encode _____ ____

reward type

nucleus accumbens neurons become ______ around time rat presses lever for reward

active

_______ respond to presses for one type of reward but not the other

neurons

spatial learning

allocentric and egocentric

allocentric

path according to external cues

egocentric

path according to one’s own position or sequential events

representation of space in brain

place cells

grid cells

boundary cells

head direction cells

place cells encode ____ _____

3D space

place cell

hippocampus

grid cells

medial entorhinal cortex

boundary cells

medial entorhinal cortex

head direction cells

presubiculum

Cells for navigating develop early and ____ with age

change

parts of the brain for spatial memory

hippocampus and cortex

parts of the brain for STM

prefrontal cortex

different regions for different attributes

sensory buffer

briefest recollection of sensory impressions

STMs

last ~30 seconds (with rehearsal, maybe a few minutes)

working memory is a form of STM

Stages of memory

1. incoming info

2. sensory buffers (encoding)

3. STM (consolidation) →

4. LTM (retrieval) ←

LTM

very large capacity (influenced by emotion)

LTM processes

encoding

consolidation

retrieval

LTM is large but subject to ______

forgetting

LTM is susceptible to alteration during _____

retrieval

Lab rates experiment: three conditions

Standard

impoverished

enriched

animals in the EC developed

heavier, thicker cortex

larger cortical synapses

more dendritic branches and spines on cortical neurons

long-term potentiation (LTP)

stable and enduring increase in effectiveness of synapses

3 circuits in hippocampus known to display LTP

1. prefrontal pathway

2. mossy fiber

3. schaffer collaterals

Tetanus

brief, high-frequency burst of electrical stimuli

Tetanus causes presynaptic neurons to produce a high rate of ______

APs

For tetanus, postsynaptic neurons respond by producing larger _______

EPSPs

most -studied form of LTP uses transmitter _______ and depends on NMDA receptors along AMPA receptors

glutamate

during normal activity, glutamate released at _____ synapses activates only AMPA receptors

CA1

NMDA receptors at rest have ________ ____ (Mg2+) blocking their calcium channels

magnesium ion

_____ receptors respond when larger quantities of glutamate are released (1)

NMDA

stronger stimulation of AMPA receptor ______ membrane, releasing Mg2+ from NMDA receptors (2)

AMPA

NMDA receptors then respond to ____ by allowing Ca2+ to enter (3)

glutamate

influx of Ca2+ activates intracellular enzymes, causing changes in ______ receptors (4)

AMPA

Presynaptic changes in LTP (1)

retrograde transmitter travels back across synapse

Presynaptic changes in LTP (2)

ensures more glutamate will be released and further strengthens synapse

Synapses that are not strengthened will become weaker and ____ _____

fade away

pharmacological treatments that block LTP also impair _______

learning

mice that overxpress NMDA receptors have enhanced LTP and better ______

LTM

research implicates LTP in ____

memory

Time course of LTP is similar to that of _____ ______

memory formation

Theory of LTM storage in cortex

experience activates some form of LTP in the hippocampal formation

axons from amygdala and hippocampus to layer 1 of cortex induce ______

plasticity

fearful stimulation intensifies plasticity specifically of the ____ _____ that have apical dendrites in layer 1

pyramidal neurons

______ makes memory last longer

plasticity

_____ makes memory more vivid

fear