Joan C. Borod - US grants

Although there has been much research documenting the limbic system as the substrate for emotion, there is also new evidence indicating a special role for the neocortex in emotional processing. The main purpose of the current project is to test current notions regarding the neuropsychology of neocortically-processed emotion within five domains: hemisphere specialization, emotional valence, processing mode, expression type, and communication channel. Hypotheses regarding interhemispheric specialization and valence will be tested: (a) right hemisphere dominance for emotion, regardless of valence; (b) right hemisphere dominance for negative emotions and left hemisphere dominance for positive emotions; and (c) right hemisphere dominance for the perception of emotions of both valences and differential dominance for expression as a function of valence. Intrahemispheric specialization as a function of processing mode also will be addressed to determine whether perception is independent from expression of emotion, with "anterior" cortical regions associated with expression and "posterior" regions with perception. To learn more about the neural systems underlying expressive behavior, both posed and spontaneous expressions will be elicited. Finally, three channels of communication (facial, prosodic, lexical) will be examined to evaluate the extent to which there is a unitary system underlying emotional processing. Subjects will be 48 right brain-damaged, 48 left brain-damaged, and 48 normal control right-handed males and females. Brain-damaged patients with anterior or posterior cortical lesions will be included. For perception, subjects will identify photographs of facial expressions, recordings of intoned sentences, and written stimuli conveying feelings. For expression, subjects will be videotaped, audiotaped, and transcribed while posing, reliving emotional experiences, and responding to emotionally-laden slides. Nonemotional tasks will also be administered to control for cognitive, perceptual, and motoric factors that might confound performance on tasks of emotional processing. An important end-product of this project will be an extensive battery of quantitative measures for the objective assessment of emotion in brain- damaged populations.

The basic premise of this proposal is that emotion is comprised of a number of components which may utilize different brain systems. These components include: affective experience (or "subjective feelings"), expressive behavior, cognitive appraisal, somatic arousal, and goal-directed activity (e.g., Plutchik, 1984). The proposed research will focus on affective experience, in particular its hedonic (i.e., pleasant/unpleasant) aspect, and its relation to expression. The unique feature of this research is the use of intrinsically hedonic and minimally cognitive stimuli to elicit affective responding in brain-damaged patients. The framework for our project emanates from the literature on laterality and emotion. Although much research has shown that the two sides of the brain differ in their involvement in emotion, many questions remain, perhaps the most important being whether they differ with respect to hedonic valence. The experimental subjects will be 16 right brain-damaged and 26 left brain- damaged patients with unilateral frontal lobe lesions from cerebrovascular pathology. Sixteen matched normal controls will also serve as subjects. Hedonic experience will be assessed through subjects' ratings of pleasant and unpleasant odors. Expression will be assessed through both spontaneous and "prompted" facial displays in response to the odors, which will be evaluated by naive judges from videotaped records. Our objective is to determine whether patients with right- and left-sided brain damage differ in hedonic experience, facial response to hedonic stimuli, and the relationship between experience and expression. This study will be the first to focus on hedonic experience and expression via olfactory stimulation in a brain-damaged population. Our work is based on the belief that understanding the neurological bases of emotion requires a research strategy in which each component can be assessed independently of the others. If this preliminary research reveals patient group differences, a proposal for a more elaborate study will be submitted, in which additional components of emotion, e.g., arousal, are systematically compared within the same group of brain-damaged patients.

Using the basic premise that emotion is comprised of a number of components which may utilize different brain systems, this study proposes to explore the reactions of brain-damaged patients to pleasant and unpleasant odors in order to maximize hedonic affective experience while simultaneously minimizing cognitive demands.