Electroconvulsive shock in rats under ether anesthesia.

Abstract

A number of studies (3,14) indicate that electroconvulsive shocks may be deleterious to maze performances of rats under a variety of learning conditions. The decrements have sometimes been ascribed (a) to the rats' becoming emotionally sensitized, frightened, or neurotic, and therefore disinclined to advance directly toward the goal; (b) to the reduction of general vigor, thereby making the rat unwilling or unable to expend the requisite amount of energy to solve the problem; and (c) to physiological alteration of cerebral functions (anoxia?) which are manifested by confusion and/or some degree of habit disintegration. These hypotheses are not mutually exclusive, hence it is quite probable that an eclectic's description of the essential causes of the rats' poorer performances in diverse maze problems will usually contain some parts of all of them. Furthermore, a complete description will entail adequate consideration of the distinctive roles played by the convulsion, on the one hand, and the nature of and circumstances attending administration of the convulsive agent, on the other.Efforts to minimize certain aspects of the convulsion, as a means of reducing the unpleasant "side effects" of convulsive therapy in man have occasionally been reported, but as yet the techniques for so doing are not well standardized. From clinical evidence (8) it has been quite generally inferred that the grand mal is necessary if the treatment is to have maximal therapeutic value; nevertheless, the clinical effects of attenuating the neural discharge have not yet been systematically investigated in studies of the relative merits of different shock techniques.Impastato, Bak, Frosch, and Wortis ( 7), [and others (9)], have reported succesful "damping" of the convulsion by intravenous injection of sodium amytal just prior to the administration of shock. This procedure reduced patient-resistance to treatment, minimized fractures, and completely abolished the period of post convulsive excitement. A minor demerit of the injection was the necessity of extending the series of treatments beyond the usual number to achieve the desired therapeutic effects. Heilbrunn (5), using 35 rats, found that if a convulsion was prevented by etherization, thus causing the rat to undergo but one mild general contraction on being shocked, brain hemorrhages (universally found in the vigorously convulsed rats) were eliminated. This line of investigation led the present authors to speculate as to what relatively constant behavioral effects of convulsions, particularly disturbances of emotional and cognitive functions,

A comparison of the effects of ECS and anesthesia on acquisition of the maze habit.

“…Comparison of the error curves for the 2-hr. ECS group (Group 4) and the control group shows results comparable to those found by other investigators (5,6) who administered ECS at longer intervals than 2 hr. after each of a series of daily maze trials.…”

Persistence and plasticity in the human memory system: An empirical investigation of the overwriting hypothesis

“…The logic here is that when ECS is delivered under anaesthetic, the subject will not experience any punishing e ects but any reverberatory activity should still be disrupted. In a study by Porter and Stone (1947) for example, rats completed a maze learning task and were then subjected to ECS either under anaesthetic (A+ condition)…”

The Effects of Epanutin and Electroconvulsive Shock on the Maze Performance of Rats

“…An eight-choice water maze of the Warden-U type was used. The maze is of the same general plan as that described by Porter & Stone (15), but longer by one unit. The correct sequence of choices is L R R L R L L R .…”