[Formation of "caudate spindles" in the sensomotor cortex of the rabbit during ontogeny].

The electrical activity elicited by electrical stimulation of the caudate nucleus in the sensorimotor and visual cortex was recorded in adult and 3-60-days old rabbits. It was shown that single stimuli applied to the caudate nucleus evoked bursts of synchronized rhythmical cortical waves similar in appearance to the so-called "caudate spindles" described in cats and monkeys. The latency of the "caudate spindles" in adult rabbit was about 200 ms, the duration--1-3 s and the frequency--11-3 c/s. The most prominent area for obtaining "caudate spindles" was the ipsilateral sensorimotor cortex. In spite of repeated efforts we have never recorded "caudate spindles" in rabbits of the youngest group. Beginning from the 15th postnatal day caudate stimulation induced bursts of rhythmical activity in the sensorimotor cortex which was similar to "caudate spindle", but with lower frequency (about 8 c/s), longer latency (350 ms) and high threshold. The definite type of spindles appears by the end of the first month of life, in the period of complication of conditioned reflexes.