|n||Firing Frequency, Hz||Action Potential|
|Amplitude, mV||Half-width, ms||Threshold, mV||Peak AHP, mV||AHP amplitude, mV|
|DA neurons||56||3.3 ± 0.2||68.5 ± 1.3||2.4 ± 0.1||−38.3 ± 0.5||−67.8 ± 0.7||29.5 ± 0.6|
|GABA neurons||28||16.4 ± 3.3||85.2 ± 2.8||1.3 ± 0.1||−42.6 ± 1.1||−72.2 ± 1.8||29.6 ± 1.3|
|P < 0.001||P < 0.0001||P < 0.0001||P < 0.01||P < 0.05||N.S.|
Average values are expressed as ± SE. Statistical comparison to assess significant differences was done by Student's t-test. Action potential (AP) amplitude was measured from AP threshold to AP peak. AP threshold was measured as a potential at which the linear fit of AP rising phase and the linear fit of slow depolarizing phase just before the abrupt change of AP rising phase crossed. AP half-width was measured half way between AP threshold and AP peak. Afterhyperpolarization (AHP) amplitude was measured from threshold to AHP peak. DA, dopamine; n, number of neurons; N.S., no significant difference; VTA, ventral tegmental area.