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Learning and Long-term Memory

開催日 2014/9/11
時間 16:00 - 17:00
会場 Poster / Exhibition(Event Hall B)

Spatial pattern similarity of ECoG responses represents associative memory in the primate medial temporal lobe

  • P1-282
  • 安達 賢 / Ken Adachi:1 川嵜 圭祐 / Keisuke Kawasaki:2 澤畑 博人 / Hirohito Sawahata:3 松尾 健 / Takeshi Matsuo:4 鈴木 隆文 / Takafumi Suzuki:5 間島 慶 / Kei Majima:6 谷川 久 / Hisashi Tanigawa:7 飯島 淳彦 / Atsuhiko Iijima:1 神谷 之康 / Yukiyasu Kamitani:6 長谷川 功 / Isao Hasegawa:2,7 中原 潔 / Kiyoshi Nakahara:8 
  • 1:新潟大院・自然科学 / Grad Sch of Sci and Tech, Niigata Univ, Niigata, Japan 2:新潟大院・医 / Niigata Univ Grad Sch of Med and Dent Sci, Niigata, Japan 3:豊橋技科大 / Toyohashi Univ of Tech, Aichi, Japan 4:東京大院・医 / The Univ of Tokyo Sch of Med, Tokyo, Japan 5:NICT・脳情報通信融合研 / CiNet, Osaka, Japan 6:ATR・脳情報研 / ATR, Kyoto, Japan 7:新潟大・超域 / Cent for Transdisciplinary Res, Niigata Univ, Niigata, Japan 8:高知工科大・総研 / Res Inst, Kochi Univ of Tech, Kochi, Japan 

Prevailing theories posit ensemble activities of neuronal populations as memory representation in the brain. Such ensemble activities may be detectable as spatiotemporal activation patterns emerging on the cortical surface. In this study, we analyzed the spatial patterns of electrocorticography (ECoG) in the monkey medial temporal lobe memory system. Three macaque monkeys were trained to memorize 5 pairs of associations between visual items, and were required to recall the associative memory in a pair association (PA) task. In each trial, one of the visual items was presented as a cue (1 sec). After a 1.5-sec delay period, up to 3 choice stimuli were sequentially presented. The monkeys were required to respond to the presentation of the paired-associate of the cue. The subjects underwent subdural implantation with a 128-channel ECoG electrode array covering a part of the perirhinal cortex. Multi-channel ECoG was recorded while the subjects performed the PA task. Task-related ECoG responses were evoked at a majority of the electrode channels. We analyzed spatial patterns of the ECoG responses during the cue period, and found that learned paired-associates evoked significantly similar pairwise activation patterns. Trial-by-trial pattern similarities were further demonstrated by a mutual decoding analysis based on multivariate machine learning. In that analysis, the activation patterns evoked in the trials with one particular visual item presented as a cue were classifiable by a machine-learning decoder trained on the activation patterns evoked in the trials where the paired-associate of that item was presented as a cue. Our results imply that highly overlapping cell assemblies represent associative memory via similar spatiotemporal cortical activation patterns.

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