learning and memory - university of...

Memory

Psychology 3910

Guest Lecture by Steve Smith

Note: Due to copyright restrictions, I had to remove the images from

the Weschler Memory Scales from the slides I posted online.

Wechsler Memory Scales - III

• Consists of 11 subtests, 6 primary and 5 optional.

• Primary

– Logical Memory (e.g.,

the “Anna Thompson

passage”; 2 tests)

– Verbal Paired

Associates (2)

– Faces (2)

– Family Pictures (2)

– Letter-Number

Sequences

– Spatial Span

• Optional

– Basic Awareness

Assessment

– Word Lists (2)

– Visual Reproduction

– Digit Span

– Mental Control

(reordering days,

months, etc.)

Rey Complex Figures Task: Assesses Spatial Memory

Specificity of Tasks

• The subtests of the WMS-III

and similar tools are not

random.

– Based on deficits shown by

patients with brain damage.

• Memory deficits can involve

different time frames as well

as different types of memory.

Outline

• Patient H.M. and the Medial Temporal Lobes

• Patient J.K. and Implicit Memory

• Patient K.C. and Two Kinds of Explicit Memory

• The Hippocampus and Memory

• Multiple Memory Systems

Part I: Patient H.M. and the

Medial Temporal Lobes • Suffered a laceration of the left supraorbital region

at age 9.

• Developed several epilepsy in his teens.

– Foci appeared to be in medial temporal lobes.

– High doses of anticonvulsants did not provide adequate

seizure control.

William Beecher Scoville

performed a bilateral anterior

temporal lobectomy on August

23, 1953.

The Extent of H.M.’s Lesion

Outcome of the Surgery

• Seizures were severely reduced.

• His overall IQ score rose from

104 to 118 (average = 100).

• Memory problems emerged.

– Dense anterograde amnesia.

“Every day is alone in itself, whatever

enjoyment I’ve had, and whatever

sorrow I’ve had… It’s like waking from a

dream; I just don’t remember.”

• Short-term memory was relatively intact

– Forward digit span = 7

– Backward digit span = 5

– Impairments emerged when stimuli exceeded STM.

– Impairments also emerged after delays.

Some Abilities are Spared

From Rempel-Clower et al. (1996)

Immediate vs. Delayed Recall in

Hippocampal Patients

• Preserved linguistic, social, motor, and basic

problem-solving skills.

• Autobiographical memory for his presurgical life

was partially preserved.

– Superior memory for remote vs. recent (presurgical)

events.

Some Abilities are Spared

H.M. and other amnesic patients, like controls, benefit from the

prior exposure. H.M. retained improvement 4 months later.

Session 1) asked H.M. to draw target patterns

Session 2) Just shown dots and asked to connect them

Findings = priming , H.M. drew more target patterns. Once again, he

had no recollection that he had ever done anything like this before.

Procedural/Motor

Memory

• Mirror-Drawing

Performance improved

dramatically.

H.M. claimed that he

had never done the

task before.

H.M. Demonstrates Memory for

Stimulus - Response Learning

Showed retention

2 years later!!!

Later Life…

• H.M. could

encode some

novel stimuli if

allowed time to

study it.

• Limited spatial

abilities

(including his

neighborhood).

• Died December 2, 2008.

Impact of H.M.

• H.M. demonstrated that damage to the hippocampus

and nearby cortex leads to anterograde amnesia.

Explicit Memory Circuit

Impact of H.M.

• His selective impairments proved that memory is

not a unitary construct.

– Different brain systems are involved in different forms

of memory.

Part II: Patient J.K. and Implicit Memory

Golin Recognition Task

Priming

• Previous experience with a stimulus influences

later responses to that stimulus.

– Influenced by perceptual factors (e.g., font, CAPS,

modality, etc.).

– Not influenced by depth of processing.

chase chase cha_ _

• Perceptual priming utilizes a posterior cortical network

involving extrastriate areas.

Patient J.K.

• Developed Parkinson’s disease

in his mid-70’s.

• Had age-normal explicit

memory.

• He was able to encode new

information about current

events.

• Impairments in performing

previously learned motoric tasks

(e.g., turning on lights).

Procedural Memory System

• Responsible for memory of rules, habits.

• An automatic, unconscious, implicit memory system.

• Affected in Huntington’s disease.

• Spared by hippocampal/diencephalic damage.

Procedural Memory System • Learning sequences of responses activates motoric

areas.

• Repeated exposure to a sequence leads to

decreased RTs.

1 2 3 4

The area of the cortex controlling the limb increased with

task mastery…even without awareness.

Remember that in the lecture, we had sample trials with 12 different responses

(e.g., 1, 4, 3, 4, 2, 1, 4, 3, 2, 1, 4, 3).

Classical Conditioning

• Animal studies indicate that the cerebellum is necessary for some forms of conditioning to occur (e.g., eyeblink conditioning). – Cerebellar lesions abolish the CR.

– But, timing is everything in the brain…

Delay vs. Trace Conditioning

• Delay Conditioning

– The CS is still present when the US starts.

– Both stimuli end at the same time.

– No memory trace is necessary.

Delay vs. Trace Conditioning

• Trace Conditioning

– There is a brief interval between the end of

the CS and the beginning of the US.

– A memory trace is required.

Delay vs. Trace Conditioning

• Delay Conditioning

– Requires activation in the

interpositus nucleus of the

cerebellum as well as in

the cerebellar cortex.

– Not impaired by hippocampal damage.

• Trace Conditioning

– Impaired by hippocampal damage.

– Does this mean it’s a form of declarative memory?

Part III: Patient K.C. and Two

Kinds of Explicit Memory

• Traumatic head injury

following a motorcycle

accident.

• Damage to the medial

temporal lobes, frontal,

parietal, and occipital

cortex (especially in the

LH).

Tulving et al. (1991). JEP.

Patient K.C.

• Preserved semantic knowledge

about real-world events.

• Preserved linguistic and analytic

skills, and STM.

• Preserved semantic knowledge

about his own life (e.g., knew which

high school he attended).

• But, he had no episodic memory

about his life.

https://www.youtube.com/watch?v=tXHk0a3RvLc

Elements of Episodic Memory

• A sense of subjective time.

• Autonoetic awareness, or the ability to be aware

of subjective time.

• A “self” that can travel in subjective time.

The Case of Clive Wearing

• https://www.youtube.com/watch?v=ipD_G

7U2FcM

Patient M.L.

• Has complete loss of autobiographical memory

for events both before and after brain injury.

• Has damage to right ventral frontal cortex.

• This region is

connected to the

medial temporal lobe

via the uncinate

fasciculus.

Implications of Patient K.C. and M. L.

• The neural substrates of episodic and semantic

memory are different.

• Episodic memory utilizes a circuit involving the

hippocampus and (left) PFC.

Part IV:

The Hippocampus and Memory

• Input from neocortex projects to the granule cells

of the dentate gyrus.

Hippocampal Anatomy

• These cells then project to pyramidal cells in

Ammon’s horn (via the mossy fibre pathway and

the Schaeffer collateral pathway).

Hippocampal circuitry

Projects to the

posterior neocortex.

Projects to the frontal

cortex, thalamus, basal

ganglia, and hypothalamus.

Hippocampal Circuit Diagram

Hippocampal Circuit Damage

• Extent of damage may influence length of

retrograde amnesia.

– Lesions isolate to CA1 (patients R.B. and D.G.) were

associated with 1-2 years of amnesia.

– Lesions to the hippocampus and surrounding

structures were associated with 15-25 years of

amnesia.

• Complete loss of the hippocampus results in

complete retrograde and anterograde amnesia.

– Some implicit memory remains (patient V.C.).

Theories of Hippocampal Function

• Site of memory storage.

• Consolidation of memories.

– Problem: some retrograde amnesia extends for

decades…were the memories stored in the

hippocampus that long?

• Address book for storage locations.

• Tagging memories with respect to context (time

and location of occurrence).

Part V: Multiple Memory Systems

• Damage to the left and right temporal lobes

leads to different patterns of deficits.

– Right temporal lobe damage leads to impairments on

face-recognition, spatial-position, and maze-learning

tasks (e.g., stylus maze).

Hemispheric Asymmetries

• Damage to the left and right temporal lobes

leads to different patterns of deficits.

– Left temporal lobe damage leads to impairments on

most language-based memory tests, as well as on the

Hebb recurring-digits test.

• No effect

in left

temporal

lobe

patients.

• HERA

– Hemispheric encoding and

retrieval asymmetry

• Frontal lobe contributes to

encoding and retrieval.

– Left PFC = encoding of both

episodic and semantic

memory.

– Right PFC = episodic

memory retrieval.

Hemispheric Asymmetries

Hippocampal vs. Perirhinal Lesions

Hippocampal vs. Perirhinal Lesions

• Animals with

hippocampal lesions

are normal on object

discrimination but

impaired on context

discrimination

• Animals with rhinal

cortex lesions show

the opposite pattern.

Hippocampal vs. Perirhinal Lesions

Diencephalic Amnesia

• Korsakoff’s syndrome – B1 (Thiamine) deficiency associated

with alcoholism.

• Neuropsychological symptoms – Anterograde amnesia

– Temporally graded retrograde amnesia

– Confabulation

– Meagre content in conversation

– Poor insight

– Apathy

Denby et al. (2009). AJNR.

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Harding et al. (2000). Brain.

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Diencephalic Amnesia

• Associated with damage to the mammillary bodies

and the dorsomedial and anterior thalamic nuclei.

Anterior Nuclei of the Thalamus

Harding et al.

(2000). Brain,

123, p. 146

Summary: Neurobiology of Memory