Fig. 1.

Subthreshold oscillations and spontaneous burst discharges are evoked by membrane depolarization. A, Membrane potential response to different levels of maintained current injection. When depolarized by adding constant current stimuli, subthreshold oscillations emerged and developed into spontaneous burst discharges after further depolarization. Bottom trace is current stimuli. B, C, High gain records of segments of membrane potential taken from A and indicated by lowercase letters. Ba, At resting membrane potential of −58 mV, prominent oscillations were not evident. Bb, Membrane depolarization produced subthreshold oscillations with a dominant frequency of ∼90 Hz and a peak-to-peak amplitude of 4.3 mV. Cc, Initiation of spikes from the peak of subthreshold membrane oscillations. Spikes are truncated. Inset taken from region of boxat a faster time base. Asterisks indicate spikes.Cd, Termination of burst discharge. Note the aborted oscillations and suppression of oscillations during the early part of the hyperpolarization after burst. The data were recorded from a P12 animal. Calibration in C applies toB.