[Wesleyan University]
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Allan Berlind

Professor Emeritus
Ph.D. (zoology) Harvard University

 

Campus Extension: 3483
Room #: Shanklin Lab 211
E-Mail: ABERLIND@WESLEYAN.EDU

 

 

 

 

 

Pattern generation by a rhythmic neural system.

 

Ongoing and projected research in this laboratory concerns the mechanisms of pattern generation by a simple neuronal system and the mechanisms by which patterns of neuronal activity are modified by neurohormones and neurotransmitters. The system being studied is the crustacean cardiac ganglion, a network of nine nerve cells that is entirely responsible for initiating and controlling a simple behavior (heart contraction). In total isolation, the ganglion is spontaneously active, in a pattern that consists of regularly repeating bursts of nerve impulses (in an intact animal, each burst would control one heart contraction). The activity of the isolated ganglion can be modified by a variety of neurohormones and neurotransmitters, which in intact animals act as cardioexcitors or cardioinhibitors.

Pattern generation (the process by which this group of nerve cells generates the bursting activity) in this system involves network interactions (nerve impulse-mediated synaptic effects and electrical transmission between the constituent nerve cells), but also a prominent role of endogenous properties of the individual neurons (unique electrical characteristics which function as "burst-organizers" even in the absence of synaptic effects).

The major focus of my current research is an electrophysiological analysis of the relative contributions of the network and endogenous components to the generation of the normal patterned output of system. This includes study of the properties of each of two classes of neurons within the ganglion (the so-called "pacemaker" neurons and the motorneurons) and the effects of activity in one neuron class on the activity of the other (including activation of the motorneurons by the pacemakers and feedback from the motorneurons to pacemakers).

A second related line of research involves neurohumoral effects on the activity of the cardiac ganglion. The internal neurochemistry of the system is almost unknown, and my laboratory is currently trying to identify neurotransmitters used within the ganglion. The mechanism of action of extrinsic modulators of ganglionic activity (e.g. hormones, or transmitters released by regulatory nerves from the central nervous system), is being analyzed by a combination of electrophysiological and pharmacological approaches.

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