title: Auditory-visual integration in fields of the auditory cortex.
abstract: While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields.
authors.affiliation: Department of Neuroinformatics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: kubota.nphy@mri.tmd.ac.jp.
authors.forename: Michinori
authors.initials: M
authors.lastname: Kubota
authors.affiliation: Department of Knowledge-Based Information Engineering, Toyohashi University of Technology, Toyohashi, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Sugimoto
authors.affiliation: Department of Physiology, University of the Ryukyus School of Medicine, Okinawa, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hosokawa
authors.affiliation: Cognitive Neurobiology and CBIR, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Ojima
authors.affiliation: Department of Knowledge-Based Information Engineering, Toyohashi University of Technology, Toyohashi, Japan.
authors.forename: Junsei
authors.initials: J
authors.lastname: Horikawa
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials; D000818:Animals; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D055724:Electrophysiological Phenomena; D005456:Fluorescent Dyes; D006168:Guinea Pigs; D008297:Male; D061848:Optical Imaging; D010775:Photic Stimulation; D011930:Reaction Time; D013343:Styrenes; D014796:Visual Perception / Q000502:physiology*
chemical_list: D005456:Fluorescent Dyes; C096453:RH 795; D013343:Styrenes
keywords: Belt fields; Core fields; Inhibition; Multimodal interactions; Optical imaging; Voltage-sensitive dye