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Learning and Memory. Dr. Kline FSU-PC. What is memory?. What do you think???. I. STM vs. LTM. Short Term Memory (STM)-- also called working memory is memory for events that have just occurred.   -Capacity is 5 to 7 units of information ± 2 (e.g., a phone number)

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Learning and Memory

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Learning and Memory

Dr. Kline

FSU-PC


What is memory?

  • What do you think???


I. STM vs. LTM

  • Short Term Memory (STM)-- also called working memory is memory for events that have just occurred.

      -Capacity is 5 to 7 units of information ± 2

    (e.g., a phone number)

  • Long Term Memory (LTM) --memory for events longer than can be held in STM & is relatively permanent.

    (e.g., Who was your first grade teacher?)


What is the process by which STM is transferred to LTM?

  • What do you think???

  • Consolidation


Neurological & behavioral evidence that STM & LTM exist independently of one another:

  • 1. People with hippocampal damage can form STM memories, but cannot form LTM memories.

  • 2. Head trauma victims have difficulty remembering events just prior to the trauma, but not for memories much earlier than the event.

  • 3. Retrieval of information from STM is easier than for LTM.


II. Explicit Vs. Implicit memory

  • Explicit memory-- memory for facts or specific events; may be directly tested for by asking the subject questions.

    “Who is the president of the United States?”

    Implicit memory --memory that does not require specific events or facts, is largely out of awareness & cannot be directly assessed.

    (riding a bike, shifting gears in car)


III. Declarative Vs. Procedural Memory

  • Declarative memory --memory that a person can state in words, is based on facts & events.

  • ---synonymous to explicit memory

  • Procedural memory --consists of motor skills.

  • ---similar to implicit memory (not all implicit memory is motor)


IV. Brain Damage: Explicit Memory impairments!

Comes from the case study of H.M (27 yrs) who had severe epileptic seizures that were damaging his brain.

He elected to have surgeons perform a  

bilateral medial temporal lobectomy to remove source of seizures.

Portions of the temporal lobe, hippocampus, & and amygdala were removed.


H.M.—Post Operative

  • H.M.’s personality & intellect were intact.

  • His IQ went up a few points & seizures were dramatically reduced.

  • However, he had massive memory deficits that radically changed his life.


Memory deficits in H.M.

  • 1. H.M. had moderate retrograde amnesia which is loss of memory for events in the past for about a year or two leading up to the surgery.

  • 2. H.M.’s memory for remote events (such as events of his childhood) was intact.

  • 3. H.M. had profound anterograde amnesia or memory loss for events that occurred following surgery.

    --He can’t form any new Long Term memories!!!!


Formal Assessment of H.M.’s Anterograde Amnesia:

  • 1. Digit Span +1 Test—5 digits were read to H.M. at 1 sec. intervals. If he got all 5 correct, on the next trial the same 5 digits were presented in the same sequence with 1 new digit added at the end & so forth for additional trials.

  • -After 25 trials of this task, H.M. still could not successfully repeat more than 7 digits (beyond STM span).

  • -Most normal Ss can learn up to 18 digits!!!


2. Verbal and Nonverbal Matching to sample tests:

  • The S is presented with a sample item & then after a delay, an array of test items is presented from which the S must select the one that matches the sample.

  • With verbal stimuli, H.M. did very well & could match the items! In contrast, H.M. performed very poorly with non-verbal stimuli.

    Why????

  • He rehearsed the verbal material thereby keeping it in STM, but couldn’t do this with the non-verbal stimuli. Thus, his STM appeared to be working.


3. Mirror Drawing Test:

  • H.M. was to draw a line within the boundaries

    of a star-shaped target by watching his hand in a

    mirror (10 trials on 3consecutive days).

  • -Errors (marks out of boundary) were calculated to determine learning.

  • -H.M. did well, showing that his implicit motor skill learning ability was intact. However, he had no memory for doing the task.


4. Rotary-Pursuit Test:

  • H.M. held a stylus in contact with a target rotating on a revolving turntable (record player).

  • He did well & improved his performance significantly over 9 daily sessions, despite not recalling doing the task.

  • Again, motor skill learning had been spared or preserved.

    But, explicit knowledge of having done the task was not.


The influence of H.M.’s case on search for Neural basis of memory:

  • 1. Was the first case to strongly implicate the medial temporal lobes in memory (hippocampus).

  • 2. H.M.’s case challenged the view that memorial functions are diffusely & equivalently distributed through the brain.

  • 3. The case provided support for the view of two distinct modes of storage for STM & LTM.

  • 4.The medial temporal lobes play an important role in memory consolidation.


V. Korsakoffs Syndrome:

  • A disease that develops in individuals who chronically consume alcohol.

  • -caused by a thiamine (vitamin B 1) deficiency that occurs almost exclusively in severe alcoholics.

  • -memory loss—severe retrograde & anterograde amnesia.

  • neurological damage is diffuse, striking damage in dorsal medial nucleus of thalamus, frontal cortex.


VI. The case of N.A. (1960)

  • N.A. was accidentally stabbed through the right nostril with a fencing foil, that penetrated his skull & went upwards in the forebrain.

  • Since the injury he had been unable to retain any new permanent memories & has had great difficulty finding employment.

  • CAT scans reveal a small lesion in the left dorsomedial nucleus of the thalamus.


VII. Alzheimer’s Disease:

  • Is a progressive degenerative disease that ultimately results in death, marked by severe retrograde & anterograde amnesia.

  • Early onset: late 40’s early 50’s prior to 60’s, is more severe that late onset!

  • -Late onset: after 65, we have 50% chance of developing this by age 85.


Alzheimer’s Disease: Symptoms

  • starts with minor forgetfulness (where’s checkbook, etc.)

  • Steadily progresses to serious memory loss

  • Depression

  • Restlessness

  • Hallucinations & delusions (seeing dead relatives)

  • Anterograde & retrograde amnesia


Alzheimer’s Disease: Genetic basis???

  • -does seem to run in families, especially in families with early onset.

  • -Best evidence--nearly all Down’s Syndrome patients will eventually develop the disease if they survive to middle age.

  • -It may depend on at least 2 or 3 different genes


Alzheimer’s Disease: Neurological damage

  • 1. There is widespread atrophy of the cortex with plaques & tangles in the hippocampus.

  • 2. Entorhinal cortex is also destroyed, acetylcholine neurons are diseased.

  • 3. The plaques contain deposits of a protein known as Beta-amyloid. An injection of this protein into a rat’s brain can damage neurons & produce symptoms resembling those of Alzheimer’s disease.


Role of hippocampus in memory

  • 1. Hippocampus--It is known that the hippocampus is critical in the consolidation of LTM.

  • It is thought that infants & young toddlers have early memory problems due to an immature hippocampus.

  • Older people with difficulty in explicit memory may show dying or diseased neurons in the hippocampus.


Evidence for hippocampus in memory:

  • 1. Case study of H.M.

  • 2. Alzheimer’s patients (often severe hippocampal damage preceeds most other damage.)

  • 3. Animal models of hippocampal damage—rats with hippocampal lesions can’t perform 8-arm radial maze task.


What is 8-arm radial maze task?

  • A rat is placed in the center of 8 arms of a maze in which food is placed in the end of the arms.

  • Rats have to learn which arms have a unique cue (e.g., rough surface) that signals they have food.

  • Normal rats learn this very fast, don’t revisit arms they’ve been to before. Rats with hippocampal damage will reenter correct arms while failing to try others.

  • In other words, they can’t remember they were there before.


Role of the frontal cortex in memory

  • The prefrontal cortex plays a large role in memory.

  • Evidence for this comes from N.A., Korsakoff’s patients, & animal models.

  • Prefrontal cortex deteriorates in older age. Aged monkeys perform more poorly on many of the same tasks as do monkeys with prefrontal cortex damage.


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