Anterior-posterior locus of lesion and personality: support for the caudality hypothesis.

Investigated the effects of discrete brain lesions on MMPI performance in well-matched samples of patients with anterior and posterior injuries. Because of the nature of the samples and careful matching for potentially confounding variables, particular emphasis could be given to the study of brain-behavior relationships. Patients with posterior lesions produced a significantly more abnormal composite MMPI profile, had a consistent tendency to produce elevated (70+) individual MMPI scales, and had individual profiles that were universally rated as abnormal using standard criteria. The differential MMPI patterns exhibited by these two samples were compatible with traditionally held clinical hypothesis with regard to distinct personality differences secondary to focal lesions in the caudal plane. It is our conclusion that lesion caudality does have a differential effect upon MMPI performance when factors such as cognitive, motor, and sensory defects are controlled adequately. The implications are that this effect is locus specific and is not necessarily related to the degree of other neurobehavioral impairment, as has been hypothesized previously.