Figure 3. Plateau properties of deep DHNs.

A, plateau potentials support an accelerating discharge during current injection (i) and a sustained after-discharge. Upper trace indicates instantaneous firing frequency, and dashed line is the mean pre-pulse resting potential. B, firing frequency and duration of the after-discharge are voltage-dependent (Ba and b, same neurone; note the different holding potentials). The after-discharge can be prematurely switched off by a brief hyperpolarising current pulse (Bb). C, noxious pinprick of a DHN excitatory receptive field (Ca, 1) can trigger a long-lasting plateau potential, which can be switched off by subsequent stimulation of an inhibitory zone of the receptive field (Cb, 2). Ca and Cb show different after-discharges of the same neurone. D, repetitive noxious stimulations of the receptive field with a 60 g Von Frey filament (Da and b, 1), evoke a strong after-discharge, which is efficiently switched off by hyperpolarising current steps (Da) or by repetitive mechanical stimulation of an inhibitory zone of the receptive field (Db, 2). Da and b, same neurone as Ba and b.