so as t o elicit noises of low intensity and pitch, comparable to the clicking sound of thc connters (7). Thc prrsrnt rcsults indicate that the greater coverage of the peripheral portion of the arena, with the parallel beams, enhanced the natural tendency to stay near the periphery, and thus reduced the number of counts on the middle beam. With the crisscross arrangement, thc morc uniform covcragc of all quadrants of the arena by the noiseproducing beams apparently elicited a more consistcnt pattern of activity and dose-response relationship.
The higher counts produced by beam D than bcam B, for the aggregated animals tested in the crisscross arrangement, indicates that the aggrcgated animals tcndcd to clump together near the periphery, either near the counters (at the base of bcam D) or away from them, thus activating beam D more often than beam B. The lack of any differcncc bctmccn the two peripheral beams ( A and C), in the parallel arrangement, indicates that there was no consistent tendency either to approach or avoid the counters. A further comparison of the parallel beams also shows that the peripheral bcams recorded higher counts than the middle beam for the animals under placebo and the low CPZ closcs, but not for those under the highest dose. -4pparetitly, the high doses of CPZ rcduccd the tendency to stay a t the periphery of the arena.
With both beam arrangements there was a large dose-aggregation interaction, with CPZ producing a greater depression in activity of grouped than single mice. This indicates a greater tranquilizing effect of this compound in the stimulating social situation, in agrccmcnt with prior findings ( 3 , 4 ) . In the photocell activity cage with six crosscross beams recording on a single counter, the lcss consistent dose-aggregation interaction (4) may be due to
In several communications Levine and. co-.