From previous work on handedness in the rat (Peterson, 1934, Peterson and Fracarol, 1938) we know that there is a highlylocalized area in the contralateral frontal region of the cerebral cortex which controls this trait. Widespread occipital and temporal destructions are without influence in producing transfers when this area is intact. It is known that after bilateral pyramidal destructions, handedness is disturbed and a temporary loss of function may occur, but with practice, the use of one hand may again become predominant. Several theories as to how this "extrapyramidal" handedness functions present themselves: 1. It may be due to vicarious functioning. 2. It may be "learning to get along without the lost functions" (Lashley, 1933). 3. It may be due to the use of a system that previously functioned with the pyramidal system.The present study seeks for other mechanisms of handedness in the brain. Two general methods of investigation were used: 1. Cerebellar destructions were produced in some cases with both pyramidal systems intact and in others with these systems destroyed. 2. Assorted cortical and subcortical destructions were produced after the pyramidal systems were destroyed.It is unfortunate that destructions in the corpus striatum could not be produced while leaving the cortex intact, but this was not possible without interfering with the fibers of the pyramidal system that run out through the basal ganglia. Brown, et al., (1936) andBeach (1941), describe methods of destroying subcortical tissue with minimal destruction of the cerebral cortex, but they do not tell us how to avoid destruction of fiber paths from the cerebral cortex that run out through the corpus striatum. Since in the rat a relatively small number of fibers are involved in handedness (under 5% destructions have been shown to pro-

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case that exemplifies many of the core features of acquired personality disorder. Goldman-Rakic, P. S. (1995). Architecture of the prefrontal cortex and the central executive. In J. Grafman, K. Holyoak, & F. Boller (Eds.), Structure and functions of the human prefrorital cortex (pp. 71-83). New York: New York Academy of Sciences. A comprehensive review of the neuroanatomy of working memory, based primarily on work on nonhuman primates. Goodwin, F. K., & Jamison. K. R. (1990). Manic-depressive illness. New York: Oxford University Press. Harlow, J. M. (1868). Recovery from the passage of an iron bar through the head. Publications of the Massachusetts Medical Society, 2, 327-347. A key paper in the history of neuropsychology; may be difficult to find. Ingvar, D. H., & Franzen, G. (1974). Distribution of cerebral activity in chronic schizophrenia. Lancet, 2, 1484- 1486. This study describes for the first time the notion of "hypofrontality," the idea that reduced frontal lobe activity plays a role in schizophrenia.