Cognitive and emotional effects of electroconvulsive shock in rats.

Abstract

A convenient portable shocking apparatus was developed which delivered shocks of known duration and magnitude. The current was adjustable from 7 to 250 milliamperes. With a shock duration of 0.2 second, current magnitudes of 35 milliamperes and 150 milliamperes, passed through a rat''s head from ear to ear, were the min. and max. values for production of complete, grand mal convulsions. Smaller values produced occasional incomplete or petit mal reactions; larger currents caused skin burns at the point of electrode contact. A reaction was induced in the rat which appeared to be analogous to petit mal in man, but the difficulty of producing this type of seizure consistently prevented an entirely satisfactory analysis of its effects. A decrement in maze performance followed convulsive treatment, apparently resulting from a loss of cognitive function, rather than from fear or weakness. Convulsions caused by min. and max. grand mal shocks were indistinguishable except for their latencies. The max. shock caused no more confusion and no higher incidence of injury than the min. A consideration of pertinent electrical principles reveals no basis for expecting moderately large currents to be harmful. A positive correlation was found between the wts. of individual rats and the amount of confusion displayed during convulsive shock treatment. There was a suggestion that the unpleasantness of the treatment was similarly related to wt. Rats shocked in the goal-box of the maze showed emotional behavior in the maze and avoided the goal-box. Results with petit mal suggest that it is more unpleasant than grand mal and causes almost as much confusion. The findings do not specifically favor any one of the various possible explanations of the cognitive loss, but they do eliminate the current-damage hypothesis and narrow the field of research somewhat. Appln. of these results to medical practice includes the suggestion that use of a high, constant shock magnitude would be simpler, more effective, and probably less unpleasant than the present procedure of attempting to use the min. convulsive dose for each individual patient.