A spindle-like wave in the cat hippocampus: a novel vigilance level-dependent electrical activity

Bursts of spindle-like waves of about 110 Hz (minispindle) were recorded from the cat hippocampus. The minispindle began to appear in parallel with the slowing of neocortical EEG and occurred most frequently during the deep slow-wave sleep episode. The minispindles could be recorded simultaneously at different points not only in the ipsilateral but also in the contralateral hippocampus with a time lag less than 30 ms.