Spatial structure of spiking correlations in the barrel cortex of anesthetized rats

V Reyes-Puerta, Y Amitai, I Shani, JJ Sun, HJ Luhmann, M Shamir

Research output: Contribution to conferenceAbstract

Abstract

The properties of correlations between neuronal firing in the
neocortex are important for cortical processing and encoding. It
has been generally assumed, by virtue of the columnar organization of the neocortex, that the firing of neurons residing in a
vertical domain is highly correlated. On the other hand, firing
correlations between neurons are assumed to be weaker and to
decline with horizontal distance. Technical difficulties in sampling multiple neurons with sufficient spatial resolution or
information on precise location have precluded the critical
evaluation of these notions. Multiple (up to 74) neurons were
recorded simultaneously during spontaneous activity in the
barrel cortex of anesthetized rats by silicon probes containing
8 shanks, each one hosting 16 electrodes. The laminar organization was determined by computing the current source densities from the local field potentials, and the location of the probe
shanks with respect to the barrels was confirmed histologically.
The time-spiking correlations were stable over periods of tens
of minutes. Using eigen decomposition, we found that the
correlations are composed of a small number of 2-3 significant
principle components. The first principle component reflects a
uniform collective mode of fluctuations, wherein all neurons
increase (or decrease) their firing rate simultaneously. On the
other hand, the second and third components demonstrate a
spatial structure. Markedly, the second component displays a
laminar structure, wherein layer 6 neurons fluctuate in opposite
direction to neurons of layers 5 and 4. Moreover, we find that
within each experiment, the distribution of the horizontal (within same lamina) correlation coefficients is practically identical
to the distribution of vertical (within same column) correlation
coefficients for horizontal distances of up to 700μm. Taken
together, these data establish the laminar position of a neuron as
a significant determinant of its spike-timing correlations.
Original languageEnglish GB
PagesS6-S6
DOIs
StatePublished - Aug 2014

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