CHAPTER 5 Bumps on the Brain: Right–Left Anatomic Asymmetry as a Key to Functional Lateralization**Preparation of this paper and some of the research reported within were supported in part by U.S. NINCDS Contract #N01-NS-6-2344 and Ontario Mental Health Foundation Grant #803. Some of the results were presented at the 13th Annual Winter Conference on Brain Research, Keystone, Colorado, Jan. 1980 and at the 19th Annual meeting of the Academy of Aphasia, London, Ont., Oct. 1981.

This chapter analyzes right–left anatomic asymmetry as a key to functional lateralization. There are two main issues associated with neuroanatomical asymmetry relevant to the discussion presented in the chapter. The first is whether the documented neuroanatomical asymmetry is a morphological substrate for the functional uniqueness of each hemisphere. If that is this the case at a gross anatomical and/or histological level, then the second concerns the possibility that the study of neuroanatomical asymmetry in relation to functional asymmetry may help elucidate some of the issues of functional lateralization, such as individual differences, the validity of perceptual indices of brain lateralization, and the genetics of laterality. This chapter presents a description of some of the consistently observed right–left neuroanatomical asymmetries. The question is addressed whether these anatomical asymmetries are in fact a morphological substrate of cerebral dominance. These issues are considered in conjunction with the implications that such neuroanatomical substrates may have for elucidating aspects of functional specialization and mechanisms of brain–behavior relationships. The optimistic view is presented in the chapter that the study of variation in neuroanatomical asymmetry may not only reveal a possible biological basis of cerebral dominance but may also serve to unlock some currently unresolved issues in functional asymmetry.