About Aplysia

The research interests of this laboratory are the neuronal and molecular mechanisms underlying learning and memory. The marine mollusc Aplysia californica and hippocampal cultures and slices are being used as model systems. In Aplysia we are studying mechanisms of implicit (nondeclarative) memory associated with simple forms of learning such as habituation, sensitization, classical or Pavlovian conditioning and operant conditioning. In hippocampal preparations we are studying mechanisms of explicit (declarative) memory associated with more complex learning processes such as remembering a place or how to solve a maze problem.

APLYSIIDEA - SEA HARES From "Molluscan Melange" Captain Alex Roth Jr. "These animals, called "Sea Hares" due to their fancied resemblance to rabbits caused by their four tentacles, are members of the sub-class. Unlike other members of the Gastropoda, they do not have outer shells to protect the soft body, but instead have a thin, triangular, twisted plate inside the body, near the centre of the back over the single gill. Some species get to be ten inches (25.4 cm) long, with a rounded body, neck and two pair of tentacles. The soft mantle forms broad swimming lobes, and many of the species are brilliantly colored. They eat seaweed and occasionally detritus. Certain of them exude a toxic purplish fluid similar to the purporin of the muricids; however, this fluid is harmless to humans."

As these studies progress, we will be able to compare and contrast learning rules and memory mechanisms among these different memory systems.

A variety of molecular, biochemical, biophysical, electrophysiological, imaging, and computer simulation techniques are used to analyze the properties of the neural circuits and the individual neurons. For example, with intracellular recording techniques we have found that simple forms of learning involve changes in synaptic transmission at existing synaptic connections. We have also determined that these changes are induced by the elevation of intracellular second messengers such as cAMP and DAG, which appear to act by modulating specific membrane channels and other cellular processes such as those associated with the machinery for transmitter release. We are now investigating how these processes are modulated both in the short-term of minutes by covalent modifications and in the long-term of days by growth factors and cAMP-induction of new gene transcription and protein synthesis. The empirical analyses are complemented with realistic mathematical modeling in order to determine whether the observed processes and their interactions are sufficient to explain the behavior of the system.

For more information about Aplysia, see: http://www.seaslugforum.net/aplycali.htm