Effects of different doses of ATM on LC single-unit sensory-evoked response expressed as percentage change from the pre-drug condition. a) Baseline activity between trials was significantly decreased at 0.3 and 1 mg/kg of ATM (both p < .005) and between 90–150 min after ATM administration. The excitatory component (b) was not affected by ATM administration compared to pre-drug levels, whereas the magnitude of the inhibitory component (c) was increased during the second time-period (90–150 min) and at 1mg/kg (p < .05). The duration of the inhibitory component (d) was increased by 3 mg/kg (p < .05) only, whereas 1mg/kg of ATM increased the phasic-to-tonic ratio (e) of LC excitatory response to paw stimulation (p < .05). f) Both 0.3 and 1 mg/kg of ATM increased the phasic-to-tonic (P:T) ratio of the inhibitory response compared to pre-drug condition (p < .05 and p < .005, respectively) and the second time window (90–150 min) was different from all the other epoch considered. Increased variability was observed on some of the measures, but only during specific time-windows. This indicates that this variability is not due to noise in the data, but to the time course of ATM effects (* = p < .05 for time).