title: Visual Responsiveness of Neurons in the Secondary Somatosensory Area and its Surrounding Parietal Operculum Regions in Awake Macaque Monkeys.
abstract: Previous neurophysiological studies performed in macaque monkeys have shown that the secondary somatosensory cortex (SII) is essentially engaged in the processing of somatosensory information and no other sensory input has been reported. In contrast, recent human brain-imaging studies have revealed the effects of visual and auditory stimuli on SII activity, which suggest multisensory integration in the human SII. To determine whether multisensory responses of the SII also exist in nonhuman primates, we recorded single-unit activity in response to visual and auditory stimuli from the SII and surrounding regions in 8 hemispheres from 6 awake monkeys. Among 1157 recorded neurons, 306 neurons responded to visual stimuli. These visual neurons usually responded to rather complex stimuli, such as stimulation of the peripersonal space (40.5%), observation of human action (29.1%), and moving-object stimulation outside the monkey's reach (23.9%). We occasionally applied auditory stimuli to visual neurons and found 10 auditory-responsive neurons that exhibited somatosensory responses. The visual neurons were distributed continuously along the lateral sulcus covering the entire SII, along with other somatosensory neurons. These results highlight the need to investigate novel functional roles-other than somesthetic sensory processing-of the SII.
authors.affiliation: Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan Section of Cognitive Neurobiology, Department of Maxillofacial Biology, Tokyo Medical and Dental University, Tokyo 113-8549, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Hihara
authors.affiliation: Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan Section of Cognitive Neurobiology, Department of Maxillofacial Biology, Tokyo Medical and Dental University, Tokyo 113-8549, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Taoka
authors.affiliation: Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan Section of Cognitive Neurobiology, Department of Maxillofacial Biology, Tokyo Medical and Dental University, Tokyo 113-8549, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan Section of Cognitive Neurobiology, Department of Maxillofacial Biology, Tokyo Medical and Dental University, Tokyo 113-8549, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iriki
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D005260:Female; D005552:Forelimb / Q000502:physiology; D007839:Functional Laterality; D006801:Humans; D008252:Macaca fascicularis; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D013003:Somatosensory Cortex / Q000166:cytology*; D014851:Wakefulness / Q000502:physiology*
keywords: Japanese monkey; auditory response; multisensory integration; single-unit recording; trimodal neuron