 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