Neuropsychological Studies of Emotional Changes Induced by Right and Left Hemispheric Lesions
Kenneth M. Heilman
Department of Neurology and Center for Neuropsychological Studies, College of Medicine, University of Florida, and Veterans Administration Medical Center, Gainesville, FL
The major assumption underlying neuropsychology is that behavior and experiential states are physically mediated by the brain. It follows that emotional behavior and affect are also physically mediated by the brain, and that pertubations of the brain may affect emotional experience (affect) and emotional behavior.
There are many ways to study how the brain may mediate emotions including electrophysiological (e.g., evoked potentials), physiological imaging (e.g., positron emission tomography), and pharmacological; however, in this chapter we review what has been learned by studying patients who have naturally occurring brain ablations secondary to neurological diseases. Based on these observations we attempt to build a model of how the brain may mediate emotion. This model, like all current neuropsychological models, is crude and most likely incorrect; however, we hope such a model will have heuristic value.
In this chapter we discuss emotional changes resulting from lesions in either hemisphere. These changes may result from interference with specific neocortical emotional functions or with cognitive processes necessary for the evaluation of stimuli that should excite emotions. These changes may also interfere with the expression of emotions or may even interfere with subjective feelings (affect). In addition to discussing how right or left hemispheric dysfunction may influence the evaluation and production of emotions and feelings, we also discuss the implications of these observations on a model of how the brain may mediate emotions and affect.