Figure 5.

Contribution of the T-current to the EPSP in TC neurons. A, Averaged EPSPs evoked in a TC neuron injected with gAMPA of various amplitudes while being maintained at three different mean membrane potentials in presence of TTX. The same sequences of gAMPA and ge/gi noise were used for each membrane potential in control condition (TTX) and in the presence of TTA-P2 (TTX+TTA-P2). T-current largely contributed to the responses evoked at −70 and −65 mV, and slightly prolonged the average EPSPs recorded at depolarized membrane potential (see inset). B1, Average EPSPs simulated in TC neuron model devoid of Na⁺ current and presenting various g_T values. B2, Selecting EPSPs that failed to trigger spike in the absence of g_T when the Na⁺ conductance is reintroduced (IT-dependent responses; see Materials and Methods) revealed a prominent contribution of the T-current at every membrane potential (see inset).