Fall 2015
Seminars are held on Tuesdays at 11:30AM in Cullimore Hall, Room 611, unless noted otherwise. For questions about the seminar schedule, please contact Casey Diekman.
Date: September 22, 2015
Speaker: Jonathan Platkiewicz
Department of Mathematics,
The City College of New York
Title: "A Needle in a Haystack: Inferring a Monosynaptic Dynamic from In Vivo Extracellular Recordings"
Abstract:
There has been recently a great deal of interest in “mapping the brain”, namely in establishing the precise structural organization of neural microcircuits. It is thought that such a map will allow us to bridge the gap between single neuron physiology and cognitive behavior. High-density extracellular recordings offer the unique opportunity to observe simultaneously the activity of hundreds of neurons with millisecond precision in the behaving mammal. Neural connectivity is typically inferred from this recording type by extracting the spikes from the extracellular potentials and estimating the pairwise correlation between spike trains. Monosynaptic connections are then detected and identified by selecting only the correlation histograms that exhibit finely-timed structures. There is however no widely-accepted biophysical justification for this procedure, nor is there much in the way of “ground truth” data that might validate these inferences. Furthermore, a recent biophysical modeling study has argued that finely-timed spike relationships cannot reflect realistic in vivo monosynaptic connections. Using tools from biophysical modeling and nonparametric statistics, we studied this apparent paradox, and provide a simple mechanistic explanation of these observations. This work can influence our understanding of synaptic spike transfer in behaving conditions, as well as methods for extracting synaptic connectivity information from extracellular data.