Gender	Male
E-mail	vladimir.brezina@mssm.edu
Education and Training	Ph.D., University of California
	Postdoctoral Training, Columbia University College of Physicians and Surgeons

Education and Training	Ph.D., University of California
	Postdoctoral Training, Columbia University College of Physicians and Surgeons

Biological Control Mechanisms
Our experimental work focuses on the central pattern generating and neuromuscular circuits that participate in various feeding behavior of the mollusc Aplysia. To be able to produce integrated and efficient behavior under a variety of circumstances, these circuits have particular structures and incorporate a number of dynamic control mechanisms. For example, their output is controlled, both centrally and in the periphery, by complex local networks of interacting neuromodulators. The experimentally advantageous Aplysia system permits the cellular effects of the modulators to be dissected, using such techniques as voltage and patch clamp, optical recordings of contractions of single muscle fibers, and intracellular calcium measurements. The effects can then be functionally reconstructed in the behavioral context in semi-intact and intact preparations, and understood conceptually with the use of realistic as well as more abstract mathematical modeling techniques. The goal is to understand not just the Aplysia system but to derive from it more general principles governing the operation of such control mechanisms in biological systems. Our experiments and theoretical studies have raised and begun to address a number of interesting questions along these lines. Can one analyze the structure of the circuit or network in terms of functional modules on the level of which the logic of the system, and the actions of its control mechanisms, might be better understood? What is the operating logic in complex biological signaling networks such as those of the multiple neuromodulators? What functional significance do different dynamics of the signal transduction steps and different temporal patterns of the signals have? How is information encoded and decoded in such networks? And finally, how do all of these factors constrain or facilitate control of one such network by another, in particular, the ability of the central nervous system to control the behavioral performance of the periphery?

Brezina V, Orekhova IV, Weiss KR. Functional uncoupling of linked neurotransmitter effects by combinatorial convergence. Science 1996 Aug 9; 273(5276): 806-810.

Brezina V, Orekhova IV, Weiss KR. Control of time-dependent biological processes by temporally patterned input. Proc Natl Acad Sci U S A 1997 Sep 16; 94(19): 10444-10449.

Brezina V, Weiss KR. Analyzing the functional consequences of transmitter complexity. Trends Neurosci 1997 Nov; 20(11): 538-543.

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.

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.

Brezina V, Orekhova IV, Weiss KR. Neuromuscular modulation in Aplysia II Modulation of the neuromuscular transform in behavior. Journal of Neurophysiology 2003 Oct; 90(4): 2613-2628.

Brezina V, Orekhova IV, Weiss KR. Neuromuscular modulation in Aplysia I Dynamic model. Journal of Neurophysiology 2003 Oct; 90(4): 2592-2612.

Horn CC, Zhurov Y, Orekhova IV, Proekt A, Kupfermann I, Weiss KR, Brezina V. Cycle-to-cycle variability of neuromuscular activity in Aplysia feeding behavior. J Neurophysiol 2004 Jul; 92(1): 157-80.

Proekt A, Brezina V, Weiss KR. Dynamical basis of intentions and expectations in a simple neuronal network. Proc Natl Acad Sci U S A 2004 Jun 22; 101(25): 9447-52.

Brezina V, Horn CC, Weiss KR. Modeling neuromuscular modulation in Aplysia. III. Interaction of central motor commands and peripheral modulatory state for optimal behavior. J Neurophysiol 2005 Mar; 93(3): 1523-56.