Abstract
If objects are collections of parts, then inferotemporal cortex (IT) is an excellent area to evaluate the hypothesis that cells signaling features to be perceptually bound fire with greater precision.
We simultaneously recorded spiking and LFP signals of 175 pairs of visually responsive IT cells while a monkey performed button presses to image pairs. The image pairs were only informative about the button press when they fell on the same colored background. This task allowed us to use new images on a daily basis and to confirm from behavior that responses were not based on single images.
We found significant increases in spike rates and raw synchrony counts when viewing informative image pairs. IT neuron responses to the same stimuli varied depending on whether the stimuli were in a salient configuration. Controlling for spike rates changes (by calculating the spike field coherence (sfc) and a jitter statistic) we observed a decorrelation of the sfc for fixations of image pairs in their grouped/salient configurations. There was also a decrease in synchrony, after controlling for rate, when first viewing an image pair in a salient/informative configuration.
Synchrony measures correlated with performance. Contrasting trials where the monkey was correct with trials where he erred revealed that for both informative and uninformative configurations a greater proportion of cell pairs showed increased synchrony on correct trials.
In general, we found that synchrony counts in IT are significantly affected by grouping, but that these changes can largely be explained by overall changes in response rates.
Burroughs-Wellcome Fund, NSF IGERT, James S. McDonnell Foundation, Sloan Foundation