猫視床下部刺激による学習行動と脳の刺激および脳の破壊

LEARNED BEHAVIOR MOTIVATED BY HYPOTHALAMIC STIMULATION AND BRAIN STIMULATION AND BRAIN LESION IN CATS

I．実験方法

　視床下部刺激によるスイッチ切り行動の学習無麻酔，無拘束の状態で，猫の視床下部，辺縁系，視床および大脳皮質の脳波記録と電気刺激が双極的にできるように手術がなされた。

　実験箱は簡単なもので，実験箱内の猫は，一定の窓の外にさがつている板を押すことにより，与えられた視床下部刺激電流を中断することができるようになつている（中尾，1958）。このような装置内で，猫視床下部の一定部位を刺激すると，猫は板を押してその刺激を中断する。これをくりかえして行なうと，刺激をあたえてから猫が板をおすまでの潜時はだんだんと短縮し，最後には，試行のたびにほぼ一定の短い潜時を示すようになる。十分に訓練しておけば，数十日間猫を放置していても，猫はこの行動をよく保持している。われわれはこれをスイッチ切り行動とよんでいる。

Effects of subcortical afterdischarges, ante-rior thalamic lesions and cortical lesions on the switch-off behavior motivated by hypo-thalamic stimulation were investigated in cats.

Afterclischarges were induced by electrical stimulation of the amygdala, the hippocam-pus, the anterior and posterior cingulate gyrus, or the medullary stria, and retention of the learned behavior was examined pre, during and post afterdischarge period.

The performance of the learned behavior was blocked during the hippocampal after-discharge (afterdischarge induced by hippo-campal stimulation) accompanied by self-sustained slow afterdischarge appeared in the amygdala, the amygdaloid afterdischarge ac-companied by self-sustained fast afterdis-charge appeared in the hippocampus, the cingulate afterdischarge accompanied by propagated or self-sustained afterdischarge in the hippocampus, or the afterdischarge of the medullar stria accompanied by propagated afterdischarge in the hypothalamus, although the animals could move with hypothalamic stimulation during these afterdischarges. Sometimes afterdischarge was spontaneously occurred in the hippocampus after cessation of cingulate afterdischarge and the animals behaved as same as during hippocampal afterdischarge.

The retention was severely impaired in the cat with lesions in dorsomedial part of the anterior ventral nucleus of the thalamus, the frontal cortex or the parietal cortex.