Fig. 4.
Distinct passive membrane properties of ascending projection neurons that demonstrate evoked burst-firing. A: average membrane capacitance of bursting (filled bars) spino-PAG neurons was higher compared with nonbursting cells (open bars) in this population (***P = 0.0002; Mann-Whitney test; right), while no significant differences were noted in the spino-PB group (P = 0.141; left). B: bursting neurons (filled bars) exhibited significantly lower membrane resistance compared with other projection neurons (open bars) in both the spino-PB (***P = 0.0008; Mann-Whitney test; left) and spino-PAG (***P < 0.0001; right) populations. C: resting membrane potential (Vrest) was more hyperpolarized in spino-PAG neurons showing burst-firing in response to current injection compared with spino-PAG cells showing other patterns of evoked discharge (***P = 0.0009; right). Data on bursting neurons originate from 5 rats for the spino-PB group and 12 rats for the spino-PAG population.