Figure 10.
RB cells, INs and VNs neurons have different firing properties. A, In response to brief stimulation (2.5 ms), RB cells (left), INs (middle), and VNs (right) fire single action potentials, as do type I and II neurons in culture (Fig. 5). Furthermore, after an action potential, VNs show a delayed depolarization (arrow), as do type II neurons in culture (Fig. 5). It is not known whether the delayed depolarization recorded in vivo from VNs was caused by synaptic input, as was the case for type II neurons in vitro (Fig. 5). B, In response to sustained current injections (150 ms), RB cells, INs, and VNs display different firing patterns. RB cells (left) fire a single action potential, as do type I neurons in culture (Fig. 5). In contrast, INs (middle) and VNs (right) fire repetitively, as do type II neurons in culture (Fig. 5). C, The frequency of action potential firing for different sustained levels of current injection differed for RB cells (circles; n = 4), INs (squares; n = 4), and VNs (triangles; n = 3). For current intensities >0.1 nA, RB cells and VNs had significantly different firing rates (*p < 0. 01; except for 1.0 nA, **p < 0.05). At 1.3 nA, VNs and INs also had significantly different firing rates (***p < 0.05).