title: Neuronal responses to face-like stimuli in the monkey pulvinar.
abstract: The pulvinar nuclei appear to function as the subcortical visual pathway that bypasses the striate cortex, rapidly processing coarse facial information. We investigated responses from monkey pulvinar neurons during a delayed non-matching-to-sample task, in which monkeys were required to discriminate five categories of visual stimuli [photos of faces with different gaze directions, line drawings of faces, face-like patterns (three dark blobs on a bright oval), eye-like patterns and simple geometric patterns]. Of 401 neurons recorded, 165 neurons responded differentially to the visual stimuli. These visual responses were suppressed by scrambling the images. Although these neurons exhibited a broad response latency distribution, face-like patterns elicited responses with the shortest latencies (approximately 50 ms). Multidimensional scaling analysis indicated that the pulvinar neurons could specifically encode face-like patterns during the first 50-ms period after stimulus onset and classify the stimuli into one of the five different categories during the next 50-ms period. The amount of stimulus information conveyed by the pulvinar neurons and the number of stimulus-differentiating neurons were consistently higher during the second 50-ms period than during the first 50-ms period. These results suggest that responsiveness to face-like patterns during the first 50-ms period might be attributed to ascending inputs from the superior colliculus or the retina, while responsiveness to the five different stimulus categories during the second 50-ms period might be mediated by descending inputs from cortical regions. These findings provide neurophysiological evidence for pulvinar involvement in social cognition and, specifically, rapid coarse facial information processing.
authors.affiliation: System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama, 930-0194, Japan.
authors.forename: Minh Nui
authors.initials: MN
authors.lastname: Nguyen
authors.forename: Etsuro
authors.initials: E
authors.lastname: Hori
authors.forename: Jumpei
authors.initials: J
authors.lastname: Matsumoto
authors.forename: Anh Hai
authors.initials: AH
authors.lastname: Tran
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Ono
authors.forename: Hisao
authors.initials: H
authors.lastname: Nishijo
mesh_terms: D000818:Animals; D058256:Brain Waves; D004192:Discrimination, Psychological; D005145:Face; D005260:Female; D008251:Macaca; D008297:Male; D009474:Neurons / Q000145:classification / Q000502:physiology*; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D020649:Pulvinar / Q000166:cytology / Q000502:physiology*; D011930:Reaction Time; D012160:Retina / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology