Relationship Between Spontaneous and Evoked Spike-Time Correlations in Primate Visual Cortex

• Published in: Journal of neurophysiology Vol. 101; no. 5; pp. 2279 - 2289
• Main Authors: Jermakowicz, Walter J, Chen, Xin, Khaytin, Ilya, Bonds, A. B, Casagrande, Vivien A
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01-05-2009; American Physiological Society
• Subjects: Animals; Animals, Newborn; Electrodes; Evoked Potentials, Visual - physiology; Galago; Neurons - physiology; Orientation - physiology; Photic Stimulation - methods; Reaction Time - physiology; Space Perception - physiology; Statistics as Topic; Time Factors; Visual Cortex - cytology; Visual Cortex - physiology; Visual Fields - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.91207.2008

1 Departments of Cell and Developmental Biology,
2 Psychology,
3 Ophthalmology and Visual Sciences,
4 Electrical Engineering and Computer Science, and
5 Medical Scientist Training Program, Vanderbilt University, Nashville, Tennessee
Submitted 12 November 2008;
accepted in final form 5 February 2009
ABSTRACT
Coincident spikes have been implicated in vision-related processes such as feature binding, gain modulation, and long-distance communication. The source of these spike-time correlations is unknown. Although several studies have proposed that cortical spikes are correlated based on stimulus structure, others have suggested that spike-time correlations reflect ongoing cortical activity present even in the absence of a coherent visual stimulus. To examine this issue, we collected single-unit recordings from primary visual cortex (V1) of the anesthetized and paralyzed prosimian bush baby using a 100-electrode array. Spike-time correlations for pairs of cells were compared under three conditions: a moving grating at the cells' preferred orientation, an equiluminant blank screen, and a dark condition with eyes covered. The amplitudes, lags, and widths of cross-correlation histograms (CCHs) were strongly correlated between these conditions although for the blank stimulus and dark condition, the CCHs were broader with peaks lower in amplitude. In both preferred stimulus and blank conditions, the CCH amplitudes were greater when the cells within the pair had overlapping receptive fields and preferred similar orientations rather than nonoverlapping receptive fields and different orientations. These data suggest that spike-time correlations present in evoked activity are generated by mechanisms common to those operating in spontaneous conditions.
Address for reprint requests and other correspondence: V. A. Casagrande, Dept. of Cell and Developmental Biology,Vanderbilt Medical School, U3218 Learned Lab, Nashville, TN 37232 (E-mail: vivien.casagrande{at}vanderbilt.edu ).