Fig. 2.

Spontaneous firing activity of LC neurons recorded from 0 to 30 min after ATM injection. a) Upper panels depicts representative rate histograms (10s bins) from 3 different LC neurons recorded in animals that received 0.1, 0.3 or 1 mg/kg ATM. It can be seen that the two higher doses, but not 0.1 mg/kg, attenuated LC spontaneous activity and that 1 mg/kg caused a much faster onset of this effect. The lower panels depict the inter-spike intervals (ISI) of the above recordings (5ms bins). b) ATM at the 0.3 and 1 mg/kg doses decreased spontaneous LC firing activity and this variable was different from the pre-drug condition during the first two time windows considered (30–90 min and 90–150 min). Firing rates recovered between 150–210 min for both effective doses. c) Representative sampling of waveforms from one LC neuron during a 30 min period. (* = p < .05, for time).