2-way avoidance behavior and concurrent intertrial activity were studied in the shuttle box in relation to stimulus and shock conditions; data were obtained on spontaneous activity and reactivity to CS. Facilitatory effects of septal lesions on avoidance behavior were independent of shock level, CS, ambient levels of stimulation, and gross manifestations of hyperreactivity. The facilitation was associated with higher intertrial activity, reflecting low incidence of freezing responses, but was not secondary to the heightened activity. Discriminative avoidance conditions did not alter the lesion-induced facilitation. Septal lesions also enhanced reactivity to phptic stimuli. The multiplicity of effects cautions against any unitary explanation of the septal syndrome.
Plasma concentrations of imipramine and amitriptyline and their desmethylated metabolites were measured in 20 children being treated for major depressive illness 2 wk. and 5 to 10 wk. after achieving drug dosages of 2.25 mg/kg body weight. At 2 wk. all children had exhibited clinical improvement, but by 10 wk. 4 of the 10 children treated with imipramine and 5 of the 10 children treated with amitriptyline had experienced clinical relapse of depressive symptoms. Tricyclic antidepressant plasma concentrations and ratios were comparable in the subgroups of children who maintained their clinical improvement and those who relapsed. There was no evidence of a systematic decline in plasma tricyclic antidepressant concentrations in those children who relapsed.
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