Previous research has indicated that low voltage fast activity (LVFA) in the neocortex and rhythmical slow activity (RSA) in the hippocampus can result from activity in either (or both) the cholinergic corticipetal projections from the basal forebrain and the serotonergic corticipetal projections from the brainstem raphe. These inputs appear to give rise, respectively, to atropine-sensitive LVFA and RSA and atropine-resistant LVFA and RSA. The atropine-sensitive and atropine-resistant waveforms have been shown to have distinctive behavioral correlates. The present experiments extend these findings by providing dose-response data on the effects of scopolamine and Ditran on neocortical activity in relation to behavior in the rat. In addition, new evidence is presented which indicates that neuroleptic drugs reduce activity in the atropine-resistant (presumably serotonergic) inputs to the hippocampus and neocortex by an indirect action involving dopamine receptors. A single dose of d-amphetamine or apomorphine appears to increase activity in the same pathway by a similar indirect action. These findings may be relevant to the psychiatric effects of neuroleptic drugs.