[The EEG pattern in the growing Japanese black calves].

Developmental EEG examination was performed in ten Japanese Black calves aged from 1 week to 10 weeks. The EEG was markedly influenced by the level of consciousness. In the alert wakefulness, the EEG was high frequency, low voltage pattern. In the wakefulness, the dominant activity was low frequency, and low voltage, high frequency activity was superimposed. In the drowsiness, the EEG was high voltage, low frequency activity pattern. In the sleep, markedly high voltage, low frequency activity was dominant. These four EEG patterns observed from the 1st week to the 10th week. During the course of the examination, high frequency, low voltage activity increased, so the EEG pattern gradually developed to the 10th week of age. In the wakefulness, theta wave and alpha wave dominant pattern was observed in seven calves. This pattern was observed after the 2nd week of age, thereafter incidence of this pattern increased to the 5th or 6th week. The frequency of theta wave and alpha wave dominant pattern increased from 6.0-7.5 Hz at the 3rd week to 7.5-9.0 Hz at the 10th week. As described above, the development of the central nervous system has attained the considerable level in the newborn calves, and thereafter continue to develop.