Memory Flashcards
Patient H.M.
• Severe epilepsy since a young age, uncontrollable
seizures
• Language, perception, motor control, attention all
normal
• Very pleasant personality!
• Higher than average IQ
• All memories up until surgery (about 1.5 years before
surgery) were intact (i.e., only a little retrograde
amnesia)
• No short-term memory problems unless he was
distracted
mirror-drawing task
Have to use the reflection of a mirror to draw
within the lines of a star (cannot see your hand or
the image directly)
• Healthy people get better and better at the task each
day.
• Although H.M. could not remember ever having
performed the task, he was able to improve drastically!
• This was another big discovery for the time: memory
comes in different forms
Declarative memory
(episodic - events, semantic – facts, knowledge) which relies on the limbic MTLs for consolidation, and motor memory, which does not.
Procedural memories
(e.g., learning to drive a car, learning to play an instrument, the mirror-drawing task) depend on simple stimulus-response reward feedback and therefore
on the basal ganglia structures.
global amnesia
like patient HM
materialspecific memory impairment
Unilateral limbic MTL (medial temporal lobes) damage
• Left MTL damage –> verbal memory impairment (e.g., recalling a list of words that you are asked to memorize, recalling the details of a short story that is read to you, recalling the name of someone you just met)
• Right MTL damage –> nonverbal memory impairment (e.g., for sounds, faces, abstract designs, how to get to a particular location, etc.)
reoccurring digit sequence test
Our short term memory span is 7 items +/- 2 (think of the length of a telephone number)
• Hebb found that if he gave undergraduate students many numerical sequences that were of a length of the student’s span+1, and one of these sequences was repeated every so often, the undergraduate student could eventually learn that sequence (he would give them the sequences verbally and they would have to repeat back)
unilateral damage experiments
• The LTh patients were basically as good as the
controls and the temporal pole patients
• The LTH patients were severely impaired. They
required many more repetitions to learn the
sequence
objects on table and have to put back in proper place
• Tested patient H.M. –> no ability whatsoever (obviously)
• Tested patients with unilateral limbic MTL damage:
- If damage was in the left MTL –> patients were just as
good as controls
- If damage was in the right MTL –> the patients with the
damage extending most posteriorly were impaired (RTH >
RTh)
Mishkin performed a variety of different bilateral
lesions and observed the results
- A+ bilateral lesions –> monkeys could perform the DNMS task
- This was expected
- A+H+ bilateral lesions (mimicking H.M.) –> monkeys failed to perform the DNMS task
- This was also expected - H+ bilateral lesions –> monkeys could perform DNMS task!!!
- This confused everyone!
processing of stimuli (declarative memories)
Neocortex Entorhinal/Perirhinal Amygdala
(Initial processing (stamp of familiarity)
of a stimulus in its (emotional contribution)
most basic form)
Hippocampus
(links formed for context)
Hippocampus
- important for spatial context & linguistic context
processing of stimuli (procedural memories)
Neocortex –> Striatum
(Implicit associations learned through stimulus-
response (e.g., how to interact with the stimulus))
How can the animals learn these tasks (e.g., VD, DNMS) that involve reward without the amygdala?
Turns out the amygdala is not required for reward feedback itself but rather the hedonic (pleasurable)
aspects of reward.
Wada Test
• Sodium amytal à sodium amobarbital à barbiturate à
central nervous system depressant/sedative.
• Inject into left internal carotid artery and left hemisphere will temporarily “shut down”.
• Patient raises both arms and names words listed in front of him/her. The right arm will fall and patient will stop talking.
• 10 minutes later, effect has worn off and patient can raise arm and continue talking!
