Figure 3. Non-burst TRN neurons lack I_T.

A, similar burst discharges are produced by both long- and short-duration current pulses. a, long-duration current pulses (1 s duration) evoke characteristic discharges in TRN neuron subtypes similar to that in Fig. 2Ab. In the same neurons, a shorter duration current pulse (50 ms duration) evokes a similar discharge as the one second pulse in each subtype of TRN neuron. B, following the addition of TTX (0.5 μm), many non-burst neurons (right) lack an LTS or any transient depolarization in response to depolarizing current steps. In contrast, typical burst (left) and atypical burst (middle) neurons produced large amplitude low threshold Ca²⁺ spikes in all neurons tested. The amplitude of the low threshold Ca²⁺ spikes in atypical burst neurons was consistently greater than in typical burst neurons. All neurons were manually hyperpolarized to membrane potentials of −80 mV (dashed line). Ca, the