罰およびCER条件づけによる反応抑制に及ぼすreserpineの効果

Abstract

Hunt and Brady (10) reported that suppression in bar-pressing responses produced by CER conditioning differed in strength from that produced by punishment. They also stated that there would be differences in quality as well as in strength. The present study was designed to investigate the differerence in suppressant effects produced by CER conditioning and electric shock punishment with administration of reserpine.After the accomplishment of bar-pressing learning in the Skinner box, rats were divided into two groups. The CER Ss were presented with the clicking noise during the third through thefourth minutes of a six-min bar-pressing period (the clicking period), and they were electrically shocked when ever the clicking noise went off. The punishment Ss received electric shock when they depressed the lever during the clicking period.Half of each group received an appropriate injection of reserpine. The dosage schedule of reserpine in mg/kg S. C. units was as follows: 1.0 on the first day, 0.5 on the second day, 0.1 on and after the third day. In Experiment 1, reserpine was administered every trial from the beginning of conditioning, in Exp. 2, from the fourth day of conditioning, and in Exp. 3, only in extinction trials. Distilled water 1cc/kg S. C. was injected to the control Ss.Several indices of suppressant effects were used: number of bar-pressing response, and crouching, and amount of defecation.Main results are as follows: 1) Of the control (no drug) Ss both CER and punishment Ss were suppressed in terms of the output of lever responses during the click period. In addition, however, CER Ss showed fear reactions such as crouching and defecation, and indicated a severe emotional disturbances. The punished Ss did not show any such reactions except when they were actually shocked.2) Reserpine blocked the formation of CER (Exp. 1) and facilitated the extinction of the CER (Exp. 3). But reserpine seemed to have a little effect on the CER when it was to be established (Exp. 2). While reserpine had no effect in punishment.3) From these results, the CER conditioning and electric shock punishment seemed to have some different aspects in their intercurrent conditioned fear.4) The control CER Ss showed greater resistance to extinction than the control punished Ss. Moreover the former Ss failed to show extinction even in the following ten extinction trials. The results were discussed in relation to the previous studies.