下側頭葉皮質細胞の反応選択性形成におけるGABA性抑制の役割

王毅、藤田一郎、村山雄亮

19回日本神経科学大会プログラム・抄録集p.182

1996711日〜13 神戸

サル下側頭葉皮質TE野の細胞は、特定の図形特徴に対して反応する。麻酔下サルにおいて、GABA-A阻害剤であるビキュキュリン(BMI)を微小電気泳動的にTE細胞に与えると、一部の刺激図形に対する反応のみが増強した。BMI投与により、元来無効であった刺激図形に対する反応が現れる場合があったが、その図形は、同じまたは近傍の電極刺入路の別の細胞の有効刺激であることが多かった。以上の結果は、反応選択性の形成がTE野でも進行しており、その過程にGABA性抑制が寄与していることを示唆する。

Contribution of GABAergic inhibition to stimulus selectivity for object features in the inferior temporal cortex.

  Neurons in area TE of the monkey inferior temporal cortex respond preferentially to particular object features.  Little is known about the mechanism that gives rise to this stimulus selectivity, although it has previously been suggested that it is created in earlier stages of the cortical pathway(V4 and TEO).  We examined effects of microiontophoretic appliciation of bicuculine methiodide(BMI), a GABA-A receptor antagonist, on visual responses of TE neurons using multibarrel electrodes in a Japanese monkey anesthetized with N2O.  Effects of BMI application on individual neurons were stimulus-specific.  Visual responses to some effective stimuli were augmented, but those to others were not affected.  With BMI application, responses were evoked in some cells by stimuli which did not evoke responses in them without BMI application.  The latter effect was observed for a particular range of stimuli which often activated other neurons along the same or surrounding recording tracks.  A general increase of neuronal excitability does not explain these effects.  We suggest that a process of creating stimulus selectivity is in progress in the TE and that GABAergic inhibition contributes to this process.


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