EEG correlates of behavior in the cat. I. Pattern discrimination and its alteration by atropine and LSD-25

Abstract

1. 1. Electrophysiological changes associated with the acquisition and retention of two visual pattern tasks in cats were found principally in the visual system (lateral geniculate and the visual area of the lateral gyrus), the midbrain reticular formation and the anterior ventral nucleus of the thalamus. 2. 2. A comparison of EEG correlates of acquisition of the two behaviors failed to reveal consistent differences. Instead, a parallel, gradual development of evoked responses during initial training occurred. During overtraining, in the single pattern there was a diminution of evoked activity; however, this was not marked in the two pattern situation. 3. 3. Atropine sulfate was found to increase latency or abolish response in a single pattern discrimination task. In a two pattern discrimination task, atropine increased response latency, caused errors of commission, and finally blocked responding in a dose related sequence. The drug effects were related to central rather than peripheral action as demonstrated by the lack of effect of atropine methylnitrate under the same conditions. The behavioral deficits were accompanied by slow waves and high voltage bursts in the spontaneous EEG from neocortical, hippocampal and subcortical areas, while the evoked responses to the conditioning stimulus during the trials were delayed in onset and increased in amplitude in the visual system as compared to the pre-drug trials. 4. 4. The effects of LSD-25 were characterized by errors of commission in both behavioral tasks. The behavioral alterations were associated with rhythmic slow wave bursts in the spontaneous EEG from neocortical and subcortical areas, and the evoked responses to the conditioning stimulus during correct trials were increased in the visual system. 5. 5. Differences in evoked responses between correct and incorrect trials were striking in the single but not in the two pattern task, but error trials were not different under either drug from controls.