The effect of electroconvulsive shock on the anticipatory gradient in the rat.

Abstract

In an effort to measure more precisely the behavioral changes effected by electroshock convulsion investigators have recently employed animals in the learning situation with some promise of rationalizing the empirics of electroconvulsive therapy (1, 2,4,10,11,15,17,18,22,23,24,25,27). Disruption of the learning function is generally reported with time scores suffering the greatest disturbance.In the development of his goal gradient hypothesis, Hull (13, 14) reports that the rat develops a positively accelerated speed-of-locomotion gradient in approaching the goal box of a straight runway. With continued experience, however, the animal manifests an "anticipatory reaction." This is evidenced by a terminal retardation, i.e., the rat decelerates in the region contiguous to the goal. This behavior implies the operation of a symbolic process. It seems best identified as a fractional goal response, a kind of "expectancy" manifestation ( 12).The present paper examines the effect of electroconvulsive shock on the anticipatory gradient. It may be here noted that Epstein and Morgan (3) have shown that this reaction is destroyed by prefrontal lobectomy in the rat. Operated animals developed a marked goal gradient but failed, with prolonged training, to develop the anticipatory gradient.Significantly, McGinnies in his study on the effect of electroshock on maze performance, has briefly commented on the absence of "anticipatory turning" and the "tendency to 'cut corners' " that characteristically appears in the elevated maze (17, p. 35).