Fig. 6

In vivo functional assessment of DREADD activity. a Correct electrode placement, marked by red DiI for in vivo PPTg electrophysiology recordings (a, top) shows ChAT+ neurons (green) co-localizing with hM3Dq + ones (red). (a, bottom) shows ChAT+ neurons (red) co-localizing with hChR2+ (yellow) ones. Arrows indicate the electrode tips. Scale bar: 20 μm. b Average extracellularly recorded action potential waveforms showing example units with predominantly negative deflections (b, left) with (blue) and without (red) a later positive deflection, (b, centre) a predominantly positive deflection and (b, right) a bipolar positive–negative deflection. Voltage deflections were normalized to the maximum or minimum deflection (100 %). c Example traces of neurons firing (c, top) regularly, (c, middle) less regularly, and (c, bottom) phasically, during -CNO. d A box and whisker plot of firing rates during -CNO for all groups. Data are median (line), interquartile range (box) and 10th - 90th percentiles (whiskers). e Example rate meter histogram depicting a PPTg neuron from an L + D rat, with large increase in firing rate during + CNO compared to -CNO. f Example rasters for two neurons responding to + CNO with increased firing rate and clearly increased regularity of firing during + CNO (lower part of each pair) compared to -CNO (upper part of each pair). An expanded time-base during +CNO facilitates comparison of firing patterns. g Average firing rates during + CNO, expressed as a percentage of the rate during -CNO for all groups. Each dot represents an individual neuron. h CV ISI during + CNO and -CNO for neurons which increased firing rate by >100 %. Differences were highly significant (**p <0.01). Each dot pair (joined by a line) represents an individual neuron