Perceptual and Moror Skills, 1976, 42, 669-670. @ Perceptual and Motor Skills 1976
AMNESIA FOR RANDOM SHAPES FOLLOWING UNILATERAL AND BILATERAL ELECTROCONVULSIVE SHOCK THERAPY R. ASHTON1 AND N. HESS University of Queensland Summary.-Three 16-point shapes were shown to 15 patients before undergoing either unilateral or bilateral electroconvulsive therapy. They were then tested for recognition following therapy. The same subjects were similarly tested for recognition memory with no intervening shock. Analysis of variance indicated no significant differential effects of the two methods of electroshock application. Electroconvulsive shock therapy may be administered either bilaterally or unilaterally. The latter method involves application of current to the right ot nondominant hemisphere (in right-handed patients) and was introduced to prevent possible lenticular opacities (Lancaster, Steinert, & Frost, 1958). However, it was also noted that unilateral shock reduced the degree of amnesia for material presented just prior to treaunent (Lancaster, et al., 1958; Levy, 1968; Zinkin & Birtchnell, 1968). Levy (1968) hypothesized that this lesser impairment of memory resulted from the more restricted area of current spread in the unilateral as compared to the bilateral technique. One criticism of the above cited studies is that where pictorial stimulus material was to be remembered it was always of familiar objects ( d o g , tables, etc.). Thus, the engrams or memory traces of these materials could have been semantically coded and stored in the dominant (usually the left) hemisphere as words. There they would be little affected by the unilateral shock applied to the nondominant hemisphere. To overcome this problem random geometric shapes were employed in the present study. Fifteen right-handed patients ( 1 0 male and 5 female) were studied; their mean age They had all been diagnosed as suffering from reactive was 33.6 yr. (range 20-63). or endogenous depression and had not received any phenothiozine drug therapy, there being evidence (Johnson, 1969) that such drugs might induce retrograde amnesia. Finally, none of the patients had been given electroconvulsive shock therapy for at least 3 mo. The stimuli to be remembered were 16-point abstract shapes. These were the first 24 from Fig. G of Vanderplas and Garvin (1959). Numbers 1 through 12 were used for the treaunent sessions and 13 through 24 for the control sessions. In the treatment session the subjects were individually shown 3 random shapes (Nos. 1, 6,9 ) for 5 sec. each 1 hr. before shock and informed that their memory for the shapes would be tested 2 hr. later. Immediately after stimulus presentation the premeditation treatment began. This consisted of I.M. atropine sulphate (.4 mg.) followed 40 min. later by I.V.methohexital sodium ( 8 0 to 100 mg.) and then I.V.saxamethonium bromide ( 9 0 to 120 mg.). Seven of the patients ( 5 males and 2 females) were then given unilateral electroshock (160 v for 1 sec.) with the electrodes over the temporal and parietal lobes of the right hemisphere. The other 8 patients ( 5 males and 3 females) received bilateral electroshock (140 v for .8 sec.) with the electrodes in the usual fronto-temporal position. After ensuring that the post-shock confusional period was over by asking questions to check orientation in space and time, the patients' memories were tested by asking them to pick out the 3 previously shown shapes from the set of 12. 'Department of Psychology, University of Queensland, St. Lucia, Q4067, Australia.
670
R. ASHTON
s: N .
HESS
The control session employed the same subjects with a similar set of 3 random shapes (NOS. 13, 17, 22) shown for 5 sec. each. After a 2-hr. period testing for recognition was carried out as above. As Zinkin and Birtchnell (1968) advised, the treatment and control sessions were kept close together in rime, with rhe former in the morning and the latter in the afternoon of the same day. T h e means and standard deviations of the recognition scores for the control and shocked subjects in the unilateral shock group were 2.43k.27 and 1.71k.24, and for the bilateral shock group 2 . 2 5 2 . 2 5 and ,872.69 respectively. Application of analysis o i variance, modified for unequal group sizes, indicated there was n o significant difference between groups for the control situation ( F = 3.99, df = 1/13, n.s.), that there .01), but that was a significant main effect of treatment ( F = 41.83, d f = 1/13, p the interaction was not significant ( F = 3.99, df = 1/13, n.s.). T h e latter finding implies that the two treatments (unilateral versus bilateral) did not produce differential amnesic effects observed. Thus, previous findings demonstrating a weaker effect of unilateral than of bilateral electroconvulsive shock on impairment of memory were not completely confirmed using non-semantically codable shapes as stimuli. T h e hypothesis concerning the site of hemispheric storage of such materials was, therefore, supported to some extent. That is, present results suggest that, when material is stored in the hemisphere receiving unilateral shock, the amnesia observed is similar to that seen following bilateral shock. T h e reason why this effect has not been noted before is simply that the pictorial material employed in similar studies has been semantically codable and hence sheltered from the full effects of unilateral electroshock by virtue of its storage in the nonshocked (left) hemisphere.
AMNESIA FOR RANDOM SHAPES FOLLOWING UNILATERAL AND BILATERAL ELECTROCONVULSIVE SHOCK THERAPY R. ASHTON1 AND N. HESS University of Queensland Summary.-Three 16-point shapes were shown to 15 patients before undergoing either unilateral or bilateral electroconvulsive therapy. They were then tested for recognition following therapy. The same subjects were similarly tested for recognition memory with no intervening shock. Analysis of variance indicated no significant differential effects of the two methods of electroshock application. Electroconvulsive shock therapy may be administered either bilaterally or unilaterally. The latter method involves application of current to the right ot nondominant hemisphere (in right-handed patients) and was introduced to prevent possible lenticular opacities (Lancaster, Steinert, & Frost, 1958). However, it was also noted that unilateral shock reduced the degree of amnesia for material presented just prior to treaunent (Lancaster, et al., 1958; Levy, 1968; Zinkin & Birtchnell, 1968). Levy (1968) hypothesized that this lesser impairment of memory resulted from the more restricted area of current spread in the unilateral as compared to the bilateral technique. One criticism of the above cited studies is that where pictorial stimulus material was to be remembered it was always of familiar objects ( d o g , tables, etc.). Thus, the engrams or memory traces of these materials could have been semantically coded and stored in the dominant (usually the left) hemisphere as words. There they would be little affected by the unilateral shock applied to the nondominant hemisphere. To overcome this problem random geometric shapes were employed in the present study. Fifteen right-handed patients ( 1 0 male and 5 female) were studied; their mean age They had all been diagnosed as suffering from reactive was 33.6 yr. (range 20-63). or endogenous depression and had not received any phenothiozine drug therapy, there being evidence (Johnson, 1969) that such drugs might induce retrograde amnesia. Finally, none of the patients had been given electroconvulsive shock therapy for at least 3 mo. The stimuli to be remembered were 16-point abstract shapes. These were the first 24 from Fig. G of Vanderplas and Garvin (1959). Numbers 1 through 12 were used for the treaunent sessions and 13 through 24 for the control sessions. In the treatment session the subjects were individually shown 3 random shapes (Nos. 1, 6,9 ) for 5 sec. each 1 hr. before shock and informed that their memory for the shapes would be tested 2 hr. later. Immediately after stimulus presentation the premeditation treatment began. This consisted of I.M. atropine sulphate (.4 mg.) followed 40 min. later by I.V.methohexital sodium ( 8 0 to 100 mg.) and then I.V.saxamethonium bromide ( 9 0 to 120 mg.). Seven of the patients ( 5 males and 2 females) were then given unilateral electroshock (160 v for 1 sec.) with the electrodes over the temporal and parietal lobes of the right hemisphere. The other 8 patients ( 5 males and 3 females) received bilateral electroshock (140 v for .8 sec.) with the electrodes in the usual fronto-temporal position. After ensuring that the post-shock confusional period was over by asking questions to check orientation in space and time, the patients' memories were tested by asking them to pick out the 3 previously shown shapes from the set of 12. 'Department of Psychology, University of Queensland, St. Lucia, Q4067, Australia.
670
R. ASHTON
s: N .
HESS
The control session employed the same subjects with a similar set of 3 random shapes (NOS. 13, 17, 22) shown for 5 sec. each. After a 2-hr. period testing for recognition was carried out as above. As Zinkin and Birtchnell (1968) advised, the treatment and control sessions were kept close together in rime, with rhe former in the morning and the latter in the afternoon of the same day. T h e means and standard deviations of the recognition scores for the control and shocked subjects in the unilateral shock group were 2.43k.27 and 1.71k.24, and for the bilateral shock group 2 . 2 5 2 . 2 5 and ,872.69 respectively. Application of analysis o i variance, modified for unequal group sizes, indicated there was n o significant difference between groups for the control situation ( F = 3.99, df = 1/13, n.s.), that there .01), but that was a significant main effect of treatment ( F = 41.83, d f = 1/13, p the interaction was not significant ( F = 3.99, df = 1/13, n.s.). T h e latter finding implies that the two treatments (unilateral versus bilateral) did not produce differential amnesic effects observed. Thus, previous findings demonstrating a weaker effect of unilateral than of bilateral electroconvulsive shock on impairment of memory were not completely confirmed using non-semantically codable shapes as stimuli. T h e hypothesis concerning the site of hemispheric storage of such materials was, therefore, supported to some extent. That is, present results suggest that, when material is stored in the hemisphere receiving unilateral shock, the amnesia observed is similar to that seen following bilateral shock. T h e reason why this effect has not been noted before is simply that the pictorial material employed in similar studies has been semantically codable and hence sheltered from the full effects of unilateral electroshock by virtue of its storage in the nonshocked (left) hemisphere.
