Psychol Res (198,6) 48:53-55 Psychological Research © Springer-Verlag 1986 Catastrophic reaction and anosognosia in anterior-posterior and left-right models of the cerebral control of emotion C. Code Communication Disorders Research Centre, School of Speech Pathology, Scraptoft Campus, Leicester Polytechnic, Leicester LET 9SU, UK Summary The anterior-posterior and left-right models of the cerebral representation of emotion produce conflicting predic- tions in some cases, and identical predictions in others, of the affective states which can result from brain damage. Some possible causes of confusion are discussed which focus on the possibility that there may be a range of affective disorders which follow brain damage, some of which may be better explained as indirect, natural reactions. It is also suggested that a partial cause of the confusion is the desire to group together all affective disorders into a single catastrophic reaction-anosog- nosia dichotomy. Recent literature illustrates the failure of neuropsychology to synthesize what has become a large body of knowledge, an extensive catalogue of research findings, clinical observations, and speculations into useful models of the cerebral processing of various aspects of behaviour (see Bradshaw & Nettleton, 1981, and accompanying commentaries; Bever, 1983). An out- standing and topical example of this problem in neuropsycho- logy is that of the contribution of the left and right hemispheres to the control of emotional or affective behaviour. The rela- tionships between the brain and the processing of emotion have become even more important in recent reports with the increas- ing interest in the interaction between emotion and language, suggested by an increasing number of findings to be represented at the level of the right hemisphere (Lamandella, 1977; Ross & Mesulam, 1979; Ross, 1981; 1983; Ley & Bryden, 1981; Bryden & Ley, 1983; Code, in preparation). It would appear that a major obstacle to progress in this area is the existence of at least three separate models of cerebral representation of emotion based primarily on clinical evidence. These are the earlier anterior-posterior model and the more contemporary and cur- rently pursued left-right models. The anterior-posterior characterization is based on the older 'dominance' model of cerebral control derived predominantly from observations on left-hemisphere damaged patients (Ben- son & Geschwind, 1975; Brown, 1975). In this model, aphasic patients with anterior left-hemisphere damage producing a nonfluent aphasia with agrammatism and relatively intact com- prehension, predominantly present with a negative, depressive affect often referred to as catastrophic reaction. Patients with posterior left-hemisphere damage, resulting in fluent parapha- sic aphasia with severe comprehension problems, tend to pres- ent with an abnormally positive, even euphoric, affect. Such patients are apparently oblivious to their true condition and this is often referred to as anosognosic indifference or denial. Although it would be wrong to suggest that the anterior-po- sterior characterization has ever been applied to the right hemisphere (derived as it was from observations on left-hemis- phere damaged patients), on a contemporary complementary specialization appreciation of the contribution of the hemis- pheres to the balance of behaviour it results in an unambiguous dichotomy. It suggests, on a simple subductive appreciation, that anterior regions of the normal brain are 'responsible' (in some sense) for positive aspects of emotion and posterior regions for negative aspects. In the damaged brain the normal positive-negative balance is disturbed resulting in the observed abnormally negative affect with anterior damage and abnormal- ly positive affect with posterior damage. A simple subductive approach produces a staightforward interpretation of the positive-negative dichotomy. The model, in fact, looks very appealing in its simplicity and would still constitute the predominant explanation if it were not for the gradual demise of the strict dominance account of hemispheric processing in favour of a more complementary specialization model. The overwhelming emphasis in recent years on the cataloguing of left vs. right hemisphere functions has produced two lateralization models of emotion, spurred on to some degree by the desire to examine the interactions between emotion and right hemisphere aspects of language. Research findings support separate interpretations of the contribution of the right hemisphere to emotion. The first and earliest (the right hemisphere model) suggests that the right hemisphere is responsible or superior for most emotional beha- viour (Schwatz, Davidson, & Maer, 1975), and the second more recent model (the left-right model) states that the right hemis- phere is responsible for negative while the left is responsible for positive emotion (Gainotti, 1969, 1972; Tucker, 1981). The former is really a right hemisphere dominance model and the latter a true complementary specialization model of emotion. Again, there is clinical evidence to support both lateralization hypotheses (Gainotti, 1969, 1972; Ley & Bryden, 1981). The left-right model predicts that a right hemisphere lesion can produce an indifferent, anosognosic mood state and a left hemisphere lesion can result in a negative, depressive, catastro- phic-reactive affective state. The evidence comes mainly from clinical studies of unilate- rally brain-damaged patients. It has been more difficult to examine the lateralization of emotion in commissurotomy sub- jects using the split-screen technique due to the spread of lateralized stimuli via the brain stem and feedback through