A multielectrode study of the inferotemporal cortex in the monkey: effects of grouping on spike rates and synchrony

We measured spiking activity from 175 pairs of visually selective neurons while a monkey performed a visual classification task in which the same image pairs appeared in informative and uninformative contexts. Spike counts and synchrony counts were higher during fixations of informative configurations. Spike field coherence showed low frequency (approximately 5-15 Hz) desynchronization when viewing informative stimulus configurations. Jitter statistics, which quantify synchrony and control for spike rates, showed less probable, more surprising patterns of synchronies when the monkey made the correct response than when he erred. Our results suggest that changes in spike counts parallel changes in raw synchrony counts and that both track aspects of stimulus context. Synchrony unexplained by rates changes, however, also occurs and correlates with performance.