Synchronous firing in the second somatosensory cortex (SII) covaries with the attentional state of alert monkey. Steinmetz, P. N., Roy, A., Fitzgerald, P., Hsiao, S. S., Niebur, E., & Johnson, K. O. Soc. Neurosci. Abstr., 28:1513, November, 1998.
abstract   bibtex   
The degree of correlated activity of pairs of neurons recorded simultaneously in area SII of an alert behaving monkey was examined. During the recordings, the animal's focus of attention switched between performing a tactile discrimination task, where the animal was required to match the orientations of two sequentially presented bars pressed onto the monkey's fingerpad, and performing a visual task, where the animal was required to detect the dimming of a figure presented on a screen while receiving identical tactile stimulation (see Fitzgerald, Lane and Hsiao, this volume for details). The neurons of each pair were recorded from different electrodes separated by at least 400 mms. Correlations were determined after applying a shift predictor to correct for variations in evoked firing rate. Of the total 101 neurons examined, 50 (50%) were members of at least one pair that showed significant effects of attention on correlation. A total of 150 pairs was examined. 18 pairs (12%) showed significant (p<0.01) synchronous firing, with the half-width of the cross-correlation peak approximately 25 ms, and with the degree of correlation covarying with the attentional state of the monkey (8% positive, 4% negative). An 8 additional pairs (5%) showed significant correlation (p<0.01) with a wider cross-correlation peak (half-width ~50 ms). 6 pairs (4%) showed significant (p<0.01) inhibition of one neuron by the other which was affected by attention, typically within 50 ms. Correlation between the remaining 118 pairs (79%) was unaffected by attention. These results indicate that attention changes not only the mean rate of firing of neurons (Hsiao et al., J. Neurophys. 7:444, 1993) but also, for nearly one half of the neurons examined, the degree of synchronization with other neurons as well.
@article{ Steinmetz_etal98a,
  author = {Steinmetz, P. N. and Roy, A. and Fitzgerald, P. and Hsiao, S. S.
	and Niebur, E. and Johnson, K. O.},
  title = {Synchronous firing in the second somatosensory cortex (SII) covaries
	with the attentional state of alert monkey},
  journal = {Soc. Neurosci. Abstr.},
  year = {1998},
  volume = {28},
  pages = {1513},
  month = {November},
  abstract = {The degree of correlated activity of pairs of neurons recorded simultaneously
	in area SII of an alert behaving monkey was examined. During the
	recordings, the animal's focus of attention switched between performing
	a tactile discrimination task, where the animal was required to match
	the orientations of two sequentially presented bars pressed onto
	the monkey's fingerpad, and performing a visual task, where the animal
	was required to detect the dimming of a figure presented on a screen
	while receiving identical tactile stimulation (see Fitzgerald, Lane
	and Hsiao, this volume for details). The neurons of each pair were
	recorded from different electrodes separated by at least 400 mms.
	Correlations were determined after applying a shift predictor to
	correct for variations in evoked firing rate.
	
	Of the total 101 neurons examined, 50 (50%) were members of at least
	one pair that showed significant effects of attention on correlation.
	A total of 150 pairs was examined. 18 pairs (12%) showed significant
	(p<0.01) synchronous firing, with the half-width of the cross-correlation
	peak approximately 25 ms, and with the degree of correlation covarying
	with the attentional state of the monkey (8% positive, 4% negative).
	An 8 additional pairs (5%) showed significant correlation (p<0.01)
	with a wider cross-correlation peak (half-width ~50 ms). 6 pairs
	(4%) showed significant (p<0.01) inhibition of one neuron by the
	other which was affected by attention, typically within 50 ms. Correlation
	between the remaining 118 pairs (79%) was unaffected by attention.
	
	These results indicate that attention changes not only the mean rate
	of firing of neurons (Hsiao et al., J. Neurophys. 7:444, 1993) but
	also, for nearly one half of the neurons examined, the degree of
	synchronization with other neurons as well.},
  downloads = {Steinmetz_etal98a.pdf; }
}

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