[A comparative neurophysiological analysis of thermoregulatory muscle activity in hibernating and nonhibernating animals during the development of hypothermia].

Comparative neurophysiological analysis of the motor units (MU) activity during hypothermia performed in ground-squirrels and rats, revealed a tendency of the MU firing rate to decrease whereas electromyographical patterns of thermoregulatory activity were found to be common both for hibernating and non-hibernating animals. The MU activity ceased in rats at their body temperature of 20-22 degrees C in contrast to 9-5 degrees C in ground-squirrels. Differences in thermoregulatory muscle tone distribution over muscle groups were found between those two species. Some mechanisms of neural regulation of cold shivering and of thermoregulatory muscle tone, are discussed.