覚醒サル側頭葉TE野のコラム構造

加藤誠、宇賀貴紀、藤田一郎

21回日本神経科学

41回日本神経化学合同大会プログラム・抄録集p.394

平成10921日(月)〜23(水)東京ビッグサイト

覚醒サルにおいてもTE野にコラム構造があるのかを調べた。ニホンザルに固視課題を訓練し、前もって作った80個の図形のセットの中から一つずつ図形を見せ、神経活動の細胞外記録を行った。電極はTE野表面に垂直または角度をつけて刺入した。図形選択性の類似度を評価するために、同じ電極刺入路状の2個のユニットの80個の図形に対する応答の発火頻度の相関を調べた。実際の電極刺入路は組織学的に確認した。皮質表面により垂直に刺入すると刺入路全体の相関係数の平均がより高くなることから、覚醒サルにおいてもTE野にコラム構造があることが示された。

COLUMNAR ORGANIZATION IN INFERIOR TEMPORAL CORTEX OF AWAKE MONKEY: VISUAL SELECTIVITY AND RESPONSE CORRELATION BETWEEN VERTICALLY AND HORIZONTALLY LOCATED UNITS.

     Evidence for a columnar organization in area TE of the inferior temporal cortex has previously been obtained in anesthetized monkeys.  In the present study, we examined the existence and nature of the columnar organization in awake monkeys.  While a Japanese monkey fixated on a small spot, 3-6 different visual stimuli from a fixed set of 80 predetermined stimuli were sequentially presented.  Nineteen electrode-guiding tubes were implanted perpendicularly or obliquely to the lateral surface of the TE.  Extracellular multiple-unit activities were recorded at intervals of more than 200μm along the tracks.  To evaluate similarity of neuronal selectivity, correlation coefficients of normalized response magnitudes were calculated among pairs of units in each track.  All electrode tracks were verified histologically.  We observed a stronger correlation among cells within vertical tracks than among cells within more oblique tracks, confirming the existence of columnar organization in the TE in awake monkeys.  Similarity of neuronal selectivities gradually decreased as the horizontal distance between units increased, suggesting that columns in the TE have relatively indistinct borders.


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