051209 Pospischil

The Bernstein Center for Computational Neuroscience Freiburg

Announcement for the next

BCCN Seminar

Dr. Martin Pospischil

Unité de Neurosciences Intégratives et Computationnelles (UNIC)
CNRS, Gif-sur-Yvette
France

DYNAMIC INTERACTIONS BETWEEN SYNAPTIC CONDUCTANCES DETERMINE SPIKE TIMING IN CORTICAL NEURONS DURING ACTIVATED STATES

During activated states in vivo, neocortical neurons are subject to intense synaptic activity and high-amplitude membrane potential (Vm) fluctuations. These high-conductance states may strongly affect the integrative properties of cortical neurons. We investigated the responsiveness of cortical neurons during different states using a combination of computational models and in vitro experiments, in which stochastic conductances were injected in dynamic-clamp. We compared two states: low-conductance states where excitatory and inhibitory conductances were of approximately equal magnitude, and high-conductance states dominated by inhibitory conductances, as typically seen in vivo. Qualitative differences between the two states were seen in spike-triggered averages of the conductances, where the high-conductance behavior was similar to the one observed in awake cats. We also investigated the differences with respect to responses (PSTH) to supplementary conductance-based excitatory inputs, as well as to dynamic modulations of spike threshold. Interestingly, the rate of Vm depolarization preceding spikes, which we confirrm was related to spike threshold, seems to depend more on the rate of variation of synaptic conductances than on their mean magnitude.

Host: Dr. Markus Diesmann