Laminar segregation of sensory coding and behavioral readout in macaque V4

Abstract

Neurons in sensory areas of the neocortex are known to represent information both about sensory stimuli and behavioral state, but how these 2 disparate signals are integrated across cortical layers is poorly understood. To study this issue, we measured the coding of visual stimulus orientation and of behavioral state by neurons within superficial and deep layers of area V4 in monkeys while they covertly attended or prepared eye movements to visual stimuli. We show that whereas single neurons and neuronal populations in the superficial layers conveyed more information about the orientation of visual stimuli than neurons in deep layers, the opposite was true of information about the behavioral relevance of those stimuli. In particular, deep layer neurons encoded greater information about the direction of planned eye movements than superficial neurons. These results suggest a division of labor between cortical layers in the coding of visual input and visually guided behavior.

Influence of On-Off dynamics and selective attention on the spatial pattern of correlated variability in neocortex

“…Spiking activity was recorded with 16-channel linear array microelectrodes ( Fig. 1a) arranged so that receptive fields (RFs) on all channels largely overlapped 22,26 . During recordings, monkeys performed a spatial attention task, which required detecting changes in the orientation of a visual stimulus in the presence of distractor stimuli.…”

“…1). In each session, data from each of the recording channels were assigned laminar depth, relative to a common current source density marker 26 . We found that noise correlations were slightly reduced in superficial and enhanced in deep layers in the attention relative to control conditions ( Fig.…”

“…Recordings were targeted with MRI to be as perpendicular to cortical layers as possible so as to maximize the overlap of receptive fields (RFs) of recorded neurons. Each of the recording channels were assigned laminar depth relative to a common current source density marker as described previously 26 .…”

Robust Encoding of Abstract Rules by Distinct Neuronal Populations in Primate Visual Cortex

“…A number of previous studies have found evidence that subpopulations of neurons within visual cortex may be engaged differently during attention (Mitchell, Sundberg, & Reynolds, 2007;Nandy, Nassi, & Reynolds, 2017;Pettine, Steinmetz, & Moore, 2019) and working memory (van Kerkoerle et al, 2017). Thus, we next asked if the rule signals we observed might be driven disproportionately by distinct subsets of neurons recorded in the daily sessions.…”

“…Lastly, we found that neurons with robust task rule signals were distributed equally across layers of V4. Previous studies have shown that both attention and working memory influence neuronal activity differently across layers of visual cortex, including in V4 (Nandy et al, 2017;Pettine et al, 2019;van Kerkoerle et al, 2017). Since our array recordings were made largely perpendicular to the cortical surface (Fig.…”