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Visual System

開催日 2014/9/13
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Hierarchical propagation of visual response through the inferior temporal cortex

  • P3-125
  • 川嵜 圭祐 / Keisuke Kawasaki:1 春名 太一 / Taichi Haruna:2 藤木 裕也 / Yuya Fujiki:2 澤畑 博人 / Hirohito Sawahata:3 谷川 久 / Hisashi Tanigawa:1 飯島 淳彦 / Atsuhiko IIjima:1 鈴木 隆文 / Takafumi Suzuki:4 長谷川 功 / Isao Hasegawa:1 
  • 1:新潟大学・医・第一生理 / Dept Physiol, Niigata Univ, Niigata, Japan 2:神戸大・理・地球惑星 / Dept Earth and Planet Sci, Kobe Univ, Kobe, Japan 3:豊橋技術科学大学・電気電子情報工学 / Dept Electrical and Electronic Inf Eng, Toyohashi Univ of Tech, Aichi, Japan 4:情報通信研究機構・脳情報通信融合研究センター / NICT Cinet, Osaka, Japan 

Converging evidence suggests that cortical visual processing is performed in a hierarchical manner. In the primate object vision, visual information is thought to be processed along the following sequence of areas: V1, V2, V4, posterior part of the inferior temporal cortex (pIT), central part of IT (cIT) and anterior part of IT (aIT). Nonetheless, the direct physiological insight on the hierarchical processing has been constrained due to the lack of appropriate techniques. In particular, it is difficult to record neural activity simultaneously from wide cortical areas at high temporal resolution. Here we conducted electrocorticography using a 128-channel 2.5 mm spaced surface electrode, which covered ventral visual areas of pIT, cIT and aIT while the monkey performed a passive visual fixation task. The high spatiotemporal resolution recording identified three repeated waves traveling from pIT to aIT after the stimulation onset. The first wave was propagation of a positive potential, which started 50 ms after the stimulation onset, followed by propagation of a negative potential with 90 ms latency. The third wave was propagation of a positive slowly traveling potential, which started with 150 ms latency. To quantify these events of activity propagations in terms of information flow, we employed symbolic local transfer entropy (SLTE) measure. We identified both feed-forward and feedback components, the information flow directing pIT to aIT and the reversed flow in each propagation. The information network defined by SLTE topography decreased its connectivity locally and increased its connectivity globally during visual stimulation, suggesting a commutating operation. These results provide direct physiological evidence of hierarchical processing in the ventral visual stream and suggest that this process involves a dynamic change in the information topography.

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