Journal Article Heterogeneous Redistribution of Facial Subcategory Information Within and Outside the Face-Selective Domain in Primate Inferior Temporal Cortex

Miyakawa, Naohisa  ,  Majima, Kei  ,  Sawahata, Hirohito  ,  Kawasaki, Keisuke  ,  Matsuo, Takeshi  ,  Kotake, Naoki  ,  Suzuki, Takafumi  ,  Kamitani, Yukiyasu  ,  Hasegawa, Isao

28 ( 4 )  , pp.1416 - 1431 , 2018-01 , Oxford University Press
ISSN:1047-3211
Description
The inferior temporal cortex (ITC) contains neurons selective to multiple levels of visual categories. However, the mechanismsby which these neurons collectively construct hierarchical category percepts remain unclear. By comparing decoding accuracywith simultaneously acquired electrocorticogram (ECoG), local field potentials (LFPs), and multi-unit activity in the macaqueITC, we show that low-frequency LFPs/ECoG in the early evoked visual response phase contain sufficient coarse category (e.g.,face) information, which is homogeneous and enhanced by spatial summation of up to several millimeters. Late-induced highfrequencyLFPs additionally carry spike-coupled finer category (e.g., species, view, and identity of the face) information, which isheterogeneous and reduced by spatial summation. Face-encoding neural activity forms a cluster in similar cortical locationsregardless of whether it is defined by early evoked low-frequency signals or late-induced high-gamma signals. By contrast,facial subcategory-encoding activity is distributed, not confined to the face cluster, and dynamically increases its heterogeneityfrom the early evoked to late-induced phases. These findings support a view that, in contrast to the homogeneous and staticcoarse category-encoding neural cluster, finer category-encoding clusters are heterogeneously distributed even outside theirparent category cluster and dynamically increase heterogeneity along with the local cortical processing in the ITC.

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