Untitled - Laboratory of Neurophysics and Physiology

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T3
Modeling and interpretation of extracellular potentials
Space Grignard, (9.00-12.20; 13.30-16.50)
Gaute T Einevoll, Norwegian University of Life Sciences, Ås, Norway
Szymon Leski, Nencki Institute of Experimental Biology, Warsaw, Poland
Espen Hagen, Norwegian University of Life Sciences, Ås, Norway
While extracellular electrical recordings have been the workhorse in electrophysiology, the interpretation
of such recordings is not trivial. The recorded extracellular potentials in general stem from a
complicated sum of contributions from all transmembrane currents of the neurons in the vicinity of
the electrode contact. The duration of spikes, the extracellular signatures of neuronal action potentials,
is so short that the high-frequency part of the recorded signal, the multi-unit activity (MUA),
often can be sorted into spiking contributions from the individual neurons surrounding the electrode.
However, no such simplifying feature aids us in the interpretation of the low-frequency part, the local
field potential (LFP). To take a full advantage of the new generation of silicon-based multielectrodes
recording from tens, hundreds or thousands of positions simultaneously, we thus need to develop new
data analysis methods grounded in the underlying biophysics. This is the topic of the present tutorial.
In the first part of this tutorial, we will go through
• the biophysics of extracellular recordings in the brain,
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