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Abstract:
The inferior convexity of the macaque prefrontal cortex (icPFC), the cortical area anterior to the arcuate and inferior to the principal sulcus, consists the final endpoint of the ventral visual stream. It has been suggested that the icPFC is involved in higher order processing of non spatial visual information like stimulus selection, attention and working memory. However, early findings demonstrated that spiking activity in the icPFC is also modulated by visual stimulation during anesthesia. Here we used multi-electrode recordings to study in more detail the neural coding of visual information as well as the spatial distribution of this information in the icPFC of the anesthetized macaque. We recorded local field potentials (LFP) and multi and single unit spiking activity, and calculated the Shannon (mutual) information between these neurophysiological signals and a dynamic movie stimulus. We found that the phase of low frequency (1-10Hz) local field potentials (LFP) conveyed significant visual information about the movie. Significant information was also conveyed by the energy of the low frequency (1-10Hz) LFP. However the mutual information between the energy of the 1-10Hz LFP and the movie was an order of a magnitude less than the information conveyed by the phase. Information in the LFP phase was distributed evenly across all recorded sites, with almost all channels lying between 50 and 150 of the average amount of information. However, the information carried by the LFP amplitude was highly clustered around a small group of electrodes. Almost half of the recorded sites carried less than 50 of the mean information across electrodes, and around 15 recorded sites had more than 3 times the average information. High frequency LFP phase and energy were highly variable across repeated presentations of the movie and were thus non-informative. Similarly, multi unit and single unit spiking activity pattern or rate codes conveyed no information about the movie. Our results show that input and intracortical processing in the icPFC during anesthesia conveys significant information about dynamic visual stimuli.
