Eric Kandel

 The cellular basis of memory is a long-lasting change in the efficacy of the synapse. This was shown by Eric Kandel, using a simple experimental model, the sea slug Aplysia. It has a protective reflex that is modified during learning.

During learning the synapse to the left in the drawing becomes activated. This leads to an increased synthesis of cAMP and protein kinases in the target cell (center). The cell nucleus (above) will be affected by the protein kinase. The final result will be an increased synthesis of new proteins and a growth of the main synapse. In this way the synapse will become more efficient and be able to release more transmitter.

Learning takes place in the synapse between sensory and motor nerve cells. A schematic wiring diagram is shown above. An increased release of transmitter each time the sensory neuron is activated leads to a stronger muscle activation. The learning process is mediated via phosphorylation, initially in the synapse resulting in short-term memory and later via changes in gene activation. This results in growth of the synapse and a long-lasting change of function. Therefore, synapses form the building blocks of memory.

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