Multisensory Integration in Non-Human Primates during a Sensory-Motor Task

Abstract

Daily our central nervous system receives inputs via several sensory modalities, processes them and integrates information in order to produce a suitable behavior. The amazing part is that such a multisensory integration brings all information into a unified percept. An approach to start investigating this property is to show that perception is better and faster when multimodal stimuli are used as compared to unimodal stimuli. This forms the first part of the present study conducted in a non-human primate’s model (n = 2) engaged in a detection sensory-motor task where visual and auditory stimuli were displayed individually or simultaneously. The measured parameters were the reaction time (RT) between stimulus and onset of arm movement, successes and errors percentages, as well as the evolution as a function of time of these parameters with training. As expected, RTs were shorter when the subjects were exposed to combined stimuli. The gains for both subjects were around 20 and 40 ms, as compared with the auditory and visual stimulus alone, respectively. Moreover the number of correct responses increased in response to bimodal stimuli. We interpreted such multisensory advantage through redundant signal effect which decreases perceptual ambiguity, increases speed of stimulus detection, and improves performance accuracy. The second part of the study presents single-unit recordings derived from the premotor cortex (PM) of the same subjects during the sensory-motor task. Response patterns to sensory/multisensory stimulation are documented and specific type proportions are reported. Characterization of bimodal neurons indicates a mechanism of audio-visual integration possibly through a decrease of inhibition. Nevertheless the neural processing leading to faster motor response from PM as a polysensory association cortical area remains still unclear.

Computational principles and models of multisensory integration

“…Promising candidates for mediating RT and accuracy benefits typically observed for audiovisual integration (often observed for speech and vocalizations) that need further investigation in the monkey temporal lobe include the belt auditory cortex [64,68*] and the upper bank of the superior temporal sulcus [69,70]. The ventrolateral prefrontal cortex [71,72], and the dorsal premotor cortex [73] are two other association areas that need to be further studied. Another important future line of research will be to expand our understanding of the role of oscillations in these brain areas and how they relate to multisensory effects observed in FRs and behavior [74].…”

Multimodal integration in behaving chickens

“…In monkeys, the simultaneous presentation of information from two modalities results in faster reactions and more correct responses (Lanz et al, 2013). Such benefits have also been reported in vertebrates beyond mammals.…”

Distant heterotopic callosal connections to premotor cortex in non-human primates

“…Interestingly these two premotor areas have already been reported to receive inputs from associative ''sensory" areas like MIP, AIP, 7a and 7b (Matelli et al, 1986;Ghosh and Gattera, 1995;Wise et al, 1997;Tanne´-Garie´py et al, 2002) known to have visual properties. Therefore these premotor areas were further investigated recently from a multisensory perspective (Lanz et al, 2013) in order to better understand their involvement in sensory-motor transformations. However, although these pathways and processes were generally found in one hemisphere because motor projections are mostly crossed when they reach the cortex (see Van der Knaap and Van der Ham, 2011 about the inhibitory theory through the corpus callosum to facilitate brain lateralization) it remains that during Fig.…”