Determinants of multisensory integration in superior colliculus neurons. I. Temporal factors

TLDR

The central nervous system integrates diverse sensory inputs to form a comprehensive representation of the external world, and multisensory superior colliculus neurons projecting to premotor areas are believed to influence attentive and orientation behaviors. The study shows that temporal disparity among sensory stimuli critically influences multisensory integration in superior colliculus neurons, with maximal response enhancement when peak discharges overlap, a monotonic decay of enhancement as disparity increases, potential depression at larger disparities, and these interactions often predictable from individual stimulus discharge trains, implying temporal relationships strongly determine attentive and orientation behaviors.

Abstract

One of the most impressive features of the central nervous system is its ability to process information from a variety of stimuli to produce an integrated, comprehensive representation of the external world. In the present study, the temporal disparity among combinations of different sensory stimuli was shown to be a critical factor influencing the integration of multisensory stimuli by superior colliculus neurons. Several temporal principles that govern multisensory integration were revealed: (1) maximal levels of response enhancement were generated by overlapping the peak discharge periods evoked by each modality; (2) the magnitude of this enhancement decayed monotonically to zero as the peak discharge periods became progressively more temporally disparate; (3) with further increases in temporal disparity, the same stimulus combinations that previously produced enhancement could often produce depression; and (4) these kinds of interactions could frequently be predicted from the discharge trains initiated by each stimulus alone. Since multisensory superior colliculus neurons project to premotor areas of the brain stem and spinal cord that control the orientation of the receptor organs (eyes, pinnae, head), they are believed to influence attentive and orientation behaviors. Therefore, it is likely that the temporal relationships of different environmental stimuli that control the activity of these neurons are also a powerful determinant of superior colliculus-mediated attentive and orientation behaviors.