See the original press release and BBCNEWS (Photo caption)
			Primary Investigators:
			Vladimir Brezina, Ph.D.
			Elizabeth Cropper, Ph.D.
			Jian Jing, Ph.D.
			Steven Rosen, Ph.D.
			Ferdinand Sven Vilim, Ph.D.
			Klaudiusz R. Weiss, Ph.D.

Cellular Mechanisms of Behavioral Plasticity:

A striking feature of even the simplest animal behaviors is that they are plastic, i.e. they can be adjusted to compensate for changes in the external environment, as well as changes in the internal state of the animal. We use a multidisciplinary approach that combines behavioral, morphological, electrophysiological, computational, cellbiological and molecular-biological techniques to explain the neural basis of various forms of short-term plasticity.

In view of the complexity of the questions that we address, we have chosen to ask them in a preparation that has a relatively simple nervous system - the marine mollusc Aplysia californica. The central nervous system of this animal is distributed into several ganglia, each of which consists of a limited number of neurons. Many neurons are large and easily identifiable as unique individuals. The ability to recognize the same neurons from animal to animal has greatly facilitated the functional characterization of individual cells as sensory neurons, motor neurons and interneurons. This in turn has allowed the reconstruction of neuronal circuits that mediate a variety of behaviors. In particular, we have studied circuits that mediate feeding behavior. These circuit-level analyses have provided new insights into the organization of neuronal networks into mediating and modulatory components, and have led to a new conceptualization of command neurons.

Another advantage of reidentifiable neurons is that they can be specifically characterized with biochemical and molecular-biological tools. Using these tools, the neurons can then be manipulated in physiological experiments. In this way we have determined the specific contributions of different transmitter substances, and obtained insights into the functional role of peptide cotransmitters as opposed to small-molecule primary transmitters. In general, we expect that our approach will yield a unified understanding of plasticity that extends from behavior all the way to the molecules involved.

Aplysia in different behavioral states. Left, Aplysia moves slowly. Middle, Aplysia lifts head after smelling food in water. Right, Subsequently, Aplysia bites. Notice mouth opening that exposes the feeding apparatus, the radula. (Photo by Timothy Kang, Jin-sheng Wu and Jian Jing)