PSYCO104 Lecture Notes - Lecture 20: Episodic Memory, Retrograde Amnesia, Gyrus
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4 Dec 2014
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October 27 2014
TL - 11
The Forebrain
Memory Formation
The Hippocampus helps support the formation of some types of long-term
memories.
People with damage to the Hippocampus have troubles encoding new
memories.
Specifically, new factual and episodic memories.
One of the effect treatments for epilepsy is to cut the corpus callosum
in half.
A particular individual, HM, had his hippocampus damaged during such a
surgery,
and was unable to learn new memories. However, it was possible for HM
to learn
how to perform new tasks by rote. E.g. He was given the task to pick up
one of
two metallic objects, one was electrified and would provide a small
shock.
Over the course of several such incidents (month), HM 'learned' not
pick up
the one that would shock him.
HM's condition is called Anterograde Amnesia -- the inability to form
new
long-term episodic or factual memories.
Retrograde amnesia is of the kind that previous memories are lost.
Motor and Somatosensory Corteces.
Near the top of of the brain.
When the Motor Cortex is stimilated with electrodes, the sensations of
limbs being moved results. Very local, move the site of stimilation and
a different limb recieves the virtual sensation.
In the case of amputees, the unused area of the motor cortex will
eventually
get 'recruited' for processing other areas of the body. May cause
strange
effects like 'phantom limb'.. brush on forehead is percieved as
something
affecting their missing limb.
Somatosensory Cortex, when stimilated, causes the feeling of textures
on
one's body.
The formation and size of these cortexes can change depending on how
the