Selectivity of local field potentials to natural images in primate V4 and prefrontal cortex

Both the extrastriate area V4 and the prefrontal cortex (PF) play an important role in the processing of visual information. Their role can be understood by examining single unit activity as well as local field potential responses that are indicators of dendro-somatic events. Here we studied the interaction between luminance- and colour-based structural information in natural images on the tuning properties of local field potential responses in both cortical areas while monkeys were performing a visual recognition task. Our analyses focused on the stimulus-locked LFP waveforms (or visually evoked potential, VEP). In both areas, a majority of sites showed significant VEPs to natural images. In addition, our analysis revealed that VEP amplitudes in V4 were strongly modulated by colour, but not by structural content of the image. In contrast, amplitudes in prefrontal cortex were strongly modulated by image structure, irrespective of colour. These results suggest, that V4 is a highly colour sensitive area as measured by the LFP, whereas the LFP in PF cortex reflects the informational content of natural images