Dejan P Zecevic PhD
Senior Research Scientist in Cellular and Molecular Physiology
Physiology of axons, dendrites and dendritic spines; Input-output function of individual nerve cells; Voltage sensitive dyes; Optical recording methods
A central question in neurobiology is how the interaction between individual neurons produces behavior and behavioral modifications. This task depends critically on how exactly are signals integrated by individual nerve cells functioning as complex operational units. Regional electrical properties of branching neuronal processes which determine the input-output function of any neuron are extraordinarily complex, dynamic, and, in the general case, impossible to predict in the absence of detailed measurements. To obtain such a measurement one would, ideally, like to be able to monitor, at multiple sites, subthreshold events as they travel from the sites of origin (synaptic contacts) and summate at particular locations to influence action potential initiation (the spiking output of a neuron). We developed a technique to carry out this type of measurement at sub-micrometer and sub-millisecond resolution, using high-resolution multisite recording of membrane potential changes with intracellular voltage-sensitive dyes.
With this approach we now investigate: (a) The non-linear and spatially inhomogeneous interactions of dendritic membrane potential signals that represent the first step in the induction of activity-dependent long-term synaptic plasticity (LTP); (b) The input–output transform performed by mitral cells, the principal projection neurons of the olfactory bulb; (c) Electrical role of individual dendritic spines; (d) Action potential initiation and propagation in the axonal arbor of cerebellar Purkinje cells and cortical pyramidal neurons.