Spatiotemporal architecture of cortical receptive fields and its impact on multisensory interactions.

Recent electrophysiology studies have suggested that neuronal responses to multisensory stimuli may possess a unique temporal signature. To evaluate this temporal dynamism, unisensory and multisensory spatiotemporal receptive fields (STRFs) of neurons in the cortex of the cat anterior ectosylvian sulcus were constructed. Analyses revealed that the multisensory STRFs of these neurons differed significantly from the component unisensory STRFs and their linear summation. Most notably, multisensory responses were found to have higher peak firing rates, shorter response latencies, and longer discharge durations. More importantly, multisensory STRFs were characterized by two distinct temporal phases of enhanced integration that reflected the shorter response latencies and longer discharge durations. These findings further our understanding of the temporal architecture of cortical multisensory processing, and thus provide important insights into the possible functional role(s) played by multisensory cortex in spatially directed perceptual processes.