Transcript The Neural Basis Of Memory

Memories
are stored throughout
our brains, and linked together
through neural pathways.
Different
brain areas are involved
in different memory types and
stages.
Eric
Kandel – Austrian Psychiatrist
Identified
changes in the
structure & function of neurons in
the brain when learning (a new
memory) occurs.
 Worked
with large seaweed eating
slugs called Aplysia californica.
 It
has a relatively simple nervous system –
only 20,000 neurons, compared to trillions
in humans.
 The
neurons can be seen by the naked
eye, so can be observed, stimulated or
removed .
Kandel
used a thin electrode to
stimulate the siphon (like a
tail). This caused the siphon to
contract.
Read
the second column on Pgs
335 of your text and summarise
Kandel’s experiment.
Kandel observed that, after learning, the
slugs neurons functioned differently
 More
neurotransmitter produced &
released
 More
dendrites developed and made
more connections with other neurons
 Synaptic
connections form –
neurotransmitter passes more easily
next time this pathway is used
 These
changes are collectively
called: LONG-TERM POTENTIATION
 With
Short-Term memory storage, there is
only an increase in the release of the
neurotransmitter
 With Long-Term memory storage, all the 3
changes mentioned on the previous slide
occur.
 Each time the memory is recalled, the
communication links in the memory circuit
are strengthened.
 Difficult to generalise to humans, but similar
changes have been found in fish, chicks and
mammals.
Thalamus
Amygdala
 The
hippocampus is just above each ear and
4cm straight into the brain, 3.5 cm long.
 Shaped like a sea-horse??, wrapped around the
thalamus, extending into the temporal lobes.
 The
hippocampus and the medial temporal lobe
are involved in the formation of new long-term
memories (not storage)
 The
-
-
Hippocampus is specifically involved in:
Deciding if the info received by the sense is
worth remembering
Mapping & organising memories before sending
them to other parts of the brain for storage –
maybe several sections at once.
Seems to provide a cross referencing system for
memories – draws all the different aspects of a
memory from parts of the brain.
 Important
in recalling spatial relationships in the
world around us. (Damage results in disorientation
& impaired ability to navigate in familiar
surroundings).
 Helps process sense of smell
 Left hippocampus – verbal memory Eg word lists &
digit span
 Right hippocampus – spatial & visual memory Eg
facial recognition, visual directions
 Mainly
involved in declarative memories (about
facts or events) – not procedural (how to do things)
 Case
Study – HM (Henry Molaison)
-
Severe epileptic – medial temporal lobes
removed to try to stop seizures
-
Most areas of functioning unaffected – except
memory
-
He couldn't remember things he experienced
after surgery; couldn’t form new memories
of personal events or general knowledge
-
ST memory worked as long as he didn’t get
distracted