The Journal of Neuroscience, March 1, 2001, 21(5):1795-1808
Long-Range Cortical Synchronization without Concomitant
Oscillations in the Somatosensory System of Anesthetized Cats
Stephane A.
Roy,
Steven P.
Dear, and
Kevin D.
Alloway
Department of Neuroscience and Anatomy, Penn State
University College of Medicine, Hershey, Pennsylvania 17033-2255
To determine whether neuronal oscillations are essential for
long-range cortical synchronization in the somatosensory system, we
characterized the incidence and response properties of gamma range
oscillations (20-80 Hz) among pairs of synchronized neurons in primary
(SI) and secondary (SII) somatosensory cortex. Synchronized SI and SII
discharges, which occurred within a 3 msec period, were detected in
13% (80 of 621) of single-unit pairs and 25% (29 of 118) of multiunit
pairs. Power spectra derived from the auto-correlation histograms
(ACGs) revealed that ~15% of the neurons forming synchronized pairs
were characterized by oscillations. Although 24% of the synchronized
neuron pairs (19/80) were characterized by oscillations in one or both
neurons, only 1% (1/80) of these pairs displayed oscillations at the
same frequency in both neurons. Similar results were observed among
pairs of multiunit responses. When single-trial responses were
analyzed, the vast majority of responses still did not exhibit
oscillations in the gamma frequency range. These results suggest that
separate populations of cortical neurons can be bound together without
being constrained by the phase relationships defined by specific
oscillatory frequencies.
Key words:
binding; corticocortical; cross-correlation analysis; cutaneous stimulation; gamma frequency; power spectrum analysis; sensory coding; thalamocortical
Copyright © 2001 Society for Neuroscience 0270-6474/01/2151795-14$05.00/0