Título:	Population coding of facial information in the monkey superior colliculus and pulvinar
Autor(es):	Nguyen, Huy Hoang Nishimaru, Hiroshi Matsumoto, Jumpei Le, Quan Van Hori, Etsuro Maior, Rafael Plakoudi Souto Tomaz, Carlos Alberto Bezerra Ono, Taketoshi Nishijo, Hisao
Assunto:	Colículo superior Macaco Pulvinar Expressão facial
Data de publicação:	21-Dez-2016
Editora:	Frontiers
Referência:	NGUYEN, Huy Hoang et al. Population coding of facial information in the monkey superior colliculus and pulvinar. Frontiers in Neuroscience, v. 10, Article 583, 21 dez. 2016. Disponível em: <http://journal.frontiersin.org/article/10.3389/fnins.2016.00583/full>. Acesso em: 4 jul. 2017. doi: http://journal.frontiersin.org/article/10.3389/fnins.2016.00583/full.
Abstract:	The superior colliculus (SC) and pulvinar are thought to function as a subcortical visual pathway that bypasses the striate cortex and detects fundamental facial information. We previously investigated neuronal responses in the SC and pulvinar of monkeys during a delayed nonmatching-to-sample task, in which the monkeys were required to discriminate among 35 facial photos of five models and other categories of visual stimuli, and reported that population coding by multiple SC and pulvinar neurons well discriminated facial photos from other categories of stimuli (Nguyen et al., 2013, 2014). However, it remains unknown whether population coding could represent multiple types of facial information including facial identity, gender, facial orientation, and gaze direction. In the present study, to investigate population coding of multiple types of facial information by the SC and pulvinar neurons, we reanalyzed the same neuronal responses in the SC and pulvinar; the responses of 112 neurons in the SC and 68 neurons in the pulvinar in serial 50-ms epochs after stimulus onset were reanalyzed with multidimensional scaling (MDS). The results indicated that population coding by neurons in both the SC and pulvinar classified some aspects of facial information, such as face orientation, gender, and identity, of the facial photos in the second epoch (50–100 ms after stimulus onset). The Euclidean distances between all the pairs of stimuli in the MDS spaces in the SC were significantly correlated with those in the pulvinar, which suggested that the SC and pulvinar function as a unit. However, in contrast with the known population coding of face neurons in the temporal cortex, the facial information coding in the SC and pulvinar was coarse and insufficient. In these subcortical areas, identity discrimination was face orientation-dependent and the left and right profiles were not discriminated. Furthermore, gaze direction information was not extracted in the SC and pulvinar. These results suggest that the SC and pulvinar, which comprise the subcortical visual pathway, send coarse and rapid information on faces to the cortical system in a bottom-up process.
Licença:	Copyright © 2016 Nguyen, Nishimaru, Matsumoto, Van Le, Hori, Maior, Tomaz, Ono and Nishijo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Fonte: <http://journal.frontiersin.org/article/10.3389/fnins.2016.00583/full>. Acesso em: 4 jul. 2017.
DOI:	https://dx.doi.org/10.3389/fnins.2016.00583
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