Gender	Male
E-mail	klaudiusz.weiss@mssm.edu
Education and Training	Ph.D., State University of New York
	Postdoctoral Training, Columbia University

Visit Dr. Klaudiusz Weiss's Lab for more information.

Education and Training	Ph.D., State University of New York
	Postdoctoral Training, Columbia University

Cellular Mechanisms of Behavioral Plasticity
We use a multidisciplinary approach that combines behavioral, morphological, electrophysiological, cell biological and molecular-biological techniques to explain the neural basis of those forms of behavioral plasticity that are due to changes in the motivational state of animals.

In view of the complexity of these questions, 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 of which 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.

Our laboratory has been using the feeding behavior of Aplysia to determine the cellular mechanisms that are responsible for those forms of behavioral plasticity that result from changes in the level of hunger and arousal of the animal. Circuit-level analysis has provided new insights into the organization of neuronal networks into mediating and modulatory systems and led to a new conceptualization of command neurons. Studies of transmitters and modulators involved in the regulation of behavior have resulted in purification and sequencing of several novel neuropeptides and to molecular cloning of the mRNA of these molecules. These neuropeptides have now been localized to specific neurons, and shown to act as cotransmitters. To a large extent our research is now focused on the role that these peptidergic cotransmitters play in optimizing the efficiency of behavior in response to changes in the motivational state of the animal. We are particularly interested in determining:

1. The relationships between different forms of behavior and the patterns of neuronal activity.
2. The dependence of peptide cotransmitter release on the pattern of neuronal activity.
3. The physiological consequences of the interactions between multiple cotransmitters.
4. The subcellular mechanisms involved in the interaction of multiple transmitters and cotransmitters, with particular emphasis on the identification of second messengers and kinases, as well as proteins phosphorylated by these kinases.

We expect that this approach will yield a unified picture in which our understanding of behavioral plasticity will extend all the way from behavior to the molecules involved.

Visit Dr. Klaudiusz Weiss's Lab for more information.

Chang DJ, Li XC, Lee YS, Kim HK, Kim US, Cho NJ, Lo X, Weiss K, Kandel ER, Kaang BK. Activation of a heterologously expressed octopamine receptor coupled only to adenylyl cyclase produces all the features of presynaptic facilitation in aplysia sensory neurons. Proc Natl Acad Sci U S A 2000 Feb 15; 97(4): 1829-34.

Brezina V, Church P, Weiss K. Temporal pattern dependence of neuronal peptide transmitter release: models and experiments. J Neurosci 2000 Sep 15; 20(18): 6760-72.

Klein AN, Weiss K, Cropper E. Glutamate is the fast excitatory neurotransmitter of small cardioactive peptide-containing Aplysia radula mechanoafferent neuron B21. Neurosci Lett 2000 Jul 28; 289(1): 37-40.

Vilim F, Cropper E, Price DA, Kupfermann I, Weiss K. Peptide cotransmitter release from motorneuron B16 in aplysia californica: costorage, corelease, and functional implications. J Neurosci 2000 Mar 1; 20(5): 2036-42.

Morgan PT, Perrins R, Looyd PE, Weiss K. Intrinsic and extrinsic modulation of a single central pattern generating circuit. J Neurophysiol 2000 Sep; 84(3): 1186-93.

Orekhova IV, Weiss K. Optimization of rhythmic behaviors by modulation of the neuromuscular transform. J Neurophysiol 2000 Jan; 83(1): 260-79.

Weiss K. The neuromuscular transform constrains the production of functional rhythmic behaviors. J Neurophysiol 2000 Jan; 83(1): 232-59.

Brezina V, Orekhova IV, Weiss K. The neuromuscular transform: the dynamic, nonlinear link between motor neuron firing patterns and muscle contraction in rhythmic behaviors. J Neurophysiol 2000 Jan; 83(1): 207-31.

Orekhova IV, Jing J, Brezina V, Dicaprio RA, Weiss K, Cropper EC. Sonometric measurements of motor-neuron-evoked movements of an internal feeding structure (the radula) in Aplysia. J Neurophysiol 2001 Aug; 86(2): 1057-1061.

Dembrow N, Jing J, Proekt A, Romero A, Vilim F, Cropper E, Weiss K. A newly identified buccal interneuron initiates and modulates feeding motor programs in aplysia. J Neurophysiol. 2003 Oct; 90(4): 2190-240.