Eric Kandel: Synaptic Changes in the Hippocampus Johnia Murray Imani Ross IB Psychology II 1A

Background Info Kandel was a pioneer in moving the study of the mind from an investigation of behavior to an investigation of impulses Deals with learning and memory in the hippocampus of the brain Memories don’t reside in a single, specific spot of the brain Neural (neurons->synapses->impulses) change occurs between the synapses

What is this?

Synapses Sites at the end of a neuron Place where nerve cells communicate with one another Use neurotransmitters as messages to each other

Getting Down to Specifics. . . 1982 Experiment Eric Kandel and James Schwartz Observing changes in sending neurons Used a California sea snail, the Aplysia

Aplysia Study A California Sea Snail Observed changes in sending neurons Has 20,000+ unusually large nerve cells Classically conditioned (Ch. 8 from last year) the snail to withdraw its gills when water is squirted at it Learning occurs Snail releases serotonin at certain synapses Becomes more efficient at transmitting signals

Aplysia Study cont’d NOVAscienceNOW – A Memorable Snail - PBS http://www.youtube.com/watch?v=yLa-cXg8BwM

Synapses and Memory Increased synaptic efficiency makes for a more efficient neural circuit Sending neurons now need less imprinting to release neurotransmitters The receiving neuron receptor cites may increase Long Term Potentiation a long-lasting strengthening of the response of a postsynaptic nerve cell to stimulation across the synapse that occurs with repeated stimulation and is thought to be related to learning and long-term memory

Synapses and Memory cont’d LTP provides a neural basis for learning and remembering associations (reference to Ch.8) Drugs that block LTP, interfere with learning At least 40 cognitive enhancers are currently in some phase of development or clinical trial Target market: those with Alzheimer’s Disease, with mild cognitive impairment

Hippocampus: Where is it located?

Hippocampus Where initial events must come here in order to be turned from short term to long term memory Short term memory is processed in the hippocampus Neurons have to cross over the synapses to leave a mark or ‘tag’ Declarative Memory A memory for fact and events People, places and objects

Hippocampus cont’d Contains a cognitive map of external environment Registers spatial information Space surrounding you (or animals) Registers single sensory modality Sight, sound, touch or pain

In short. . . Synaptic changes affect our learning ability and memory Memories are stored in different places A lot of work is done in the hippocampus Don’t do drugs Snails are more than just slimy creatures that look nasty There’s still a lot to be discovered about the brain

Reference List Myers, David G. (2006) Psychology (AP Edition). :Macmillan – Worth Publishers. Mayford, Mark; Siegelbaum, Steven A; Kandel, Eric R. (2012) Synapses and memory storage. CSH Perspectives in Biology, 4(6). Retrieved from http://cshperspectives.cshlp.org/content/4/6/a005751.full