TABLE 1.Membrane properties of spontaneously firing DA VTA neurons measured with nystatin-perforated patch recording
|
|
Cell capacitance, pF | 33.0 ± 0.9 (n = 72) |
AP parameters (n = 72) | |
Amplitude, mV | 74.7 ± 1.1 |
Half-width, ms | 2.0 ± 0.1 |
Threshold, mV | –38.6 ± 0.4 |
AHP amplitude, mV | 26.1 ± 0.6 |
Input resistance, MΩ | 902.4 ± 43.5 (n = 20) |
Estimated RMP, mV | –48.5 ± 0.7 (n = 20) |
Firing frequency, Hz | 2.6 ± 0.2 (n = 72) |
Values are means ± SE. Numbers of neurons (n) are in parentheses. Cell capacitance was measured after the capacitive transients were cancelled. Action potential (AP)
parameters were measured from spontaneous APs recorded in current-clamp mode at resting membrane potential (no current injection).
AP amplitude was measured from threshold to AP peak. AP half-width was measured as the duration of the spike halfway between
threshold and the AP peak. Afterhyperpolarization (AHP) amplitude was measured from threshold to the peak of the AHP. In 20
of these 72 cells, input resistance and estimated resting membrane potential (RMP) were also measured. Input resistance was
determined by hyperpolarizing current pulses that induced a voltage shift of 10–15 mV negative to the resting potential, a
voltage range in which Ih (voltage sag on current-clamp recording) was not present (Koyama et al. 2005). Estimated RMP was determined by the membrane
potential measured at 60 ms before the peak of the spontaneous AP (Brodie et al. 1999a).