Which sea slug genus was central to Eric Kandel’s learning and memory research? The genus was Aplysia. Its simple nervous system made it possible to trace changes in behavior down to specific neurons and synapses.
Kandel and his colleagues focused especially on Aplysia californica, the California sea hare or sea slug. They studied its defensive gill-withdrawal reflex, in which the animal retracts delicate gill tissue after a threatening touch. The reflex can undergo habituation, sensitization, and conditioning, giving researchers measurable forms of learning in an animal with far fewer neurons than a mammal.
This reductionist strategy helped show that learning changes the effectiveness of synaptic connections. Work on Aplysia connected short-term memory with biochemical changes in existing synapses and linked long-term memory with gene expression, protein synthesis, and the growth of additional synaptic connections. Kandel shared the 2000 Nobel Prize in Physiology or Medicine for discoveries concerning signal transduction in the nervous system. A common mistake is to treat Aplysia as a species name; it is a genus containing several sea-hare species, including Aplysia californica.