No differences in ChR2-YFP expression profile were observed between F2s originating from the same founder. Coronal slices (325 μm) were obtained from adult rats (3 months or older) previously injected
with virus (see Supplemental Experimental Procedures for details). In the analysis Doxorubicin of in vitro electrophysiology, listed membrane potential refers to the initial potential measured immediately after attaining whole-cell configuration. To measure the magnitude of the hyperpolarization-activated inward Ih current, cells were held at −40mV, and a 500 ms voltage step to −120mV was applied. Ih was measured as the difference between the initial capacitative response to the voltage step (usually ∼20–40 ms after the beginning of the voltage step) and the final steady-state current the end of the 500 ms pulse; responses greater than 115 pA were classified as Ih/large. The apparent input resistance was calculated from the linear portion
of the steady-state I-V curve obtained by applying 500 ms hyperpolarizing current pulse steps. selleck products Action potential threshold was measured as the voltage at which the first-order derivative of the membrane potential (dV/dt) exhibited a sharp transition (typically > 10mV/ms). The action potential threshold was also used to set the threshold in determining spike fidelity (% of successful action potential after various light stimulation frequencies). Peak and steady-state photocurrents were measured from a 1 s light pulse in voltage-clamp mode. Series resistances were carefully monitored and recordings were not used if the series resistance changed significantly (by >20%) or reached 20 MΩ. Statistical analysis was performed with a two-tailed Student’s t test, with a level of significance set at p < 0.05. Simultaneous optical stimulation and extracellular electrical recording were performed in anesthetized rats as described previously (Gradinaru et al., 2007). See Supplemental Experimental Procedures for details. Coronal brain slices (300–400 μm) were prepared from MTMR9 adult rats previously injected with virus. A carbon-fiber glass electrode was positioned in the NAc under fluorescent guidance. Voltammetric measurements
were made every 100 ms by application of a triangular waveform (−0.4V to +1.3V, at 400V/s) to the carbon-fiber electrode versus an Ag/AgCl reference electrode. To estimate changes in DA release, background current at the electrode was subtracted from the current measured immediately following optical stimulation. Background-subtracted cyclic voltammogram showed peak oxidation and reduction currents at ∼650mV and −200mV, respectively, indicating that the signals were due to the detection of evoked DA release, and consistent with previous results. See Supplemental Experimental Procedures for additional details. Fifteen male Th::Cre rats, 300–550 g at the start of the experiment, were individually housed in a light-regulated (12 hr light/dark cycle, lights on at 07:00) colony room.