independent? What are the mechanisms by which the balance of activation is maintained? Furthermore, in attempting to discern a broad pattern, this review has blurred distinctions between occipital, temporal, and parietal areas, frequently subsuming them under the heading "posterior". Examination of the validity of these conceptualizations will certainly focus, in part, on a more finely tuned analysis of specific cortical areas in relation to emotion. Another issue involves the well-established importance in emotional function of the limbic system ( Kelley & Stinus, 1984; MacLean, 1969; Papez, 1937; also see Starkstein , Robinson, & Price, 1987). How does the limbic system interact with the cortex to modulate emotion? Neurochemical transmission between limbic and cortical structures that affects arousal and activation of various brain structures may be a crucial link in the cortical/subcortical interaction ( Starkstein & Robinson , 1988; Starkstein, Robinson, & Price, 1987; Tucker & Williamson, 1984). The specifics of these interactions remains a challenge for future research.
Finally, the brain regions involved in emotion are clearly engaged in a dynamic interaction which requires sophisticated neural communication and coordination. Thus, in children or other individuals where neural communication is immature or has been disrupted, predictions can be made as to ways in which emotional function may be different or disregulated. Furthermore, investigation of different subgroups of patients with affective disorders may help to clarify the neurological mechanisms underlying their symptom profiles. Certain disparities between the neuropsychological performance of unipolar versus bipolar patients, for example, suggest that different patterns of brain activity may underlie the differences in symptomatology manifested by these two types of patients.
Although the answers to these questions await further study, both basic and clinical science will benefit from the interdisciplinary efforts that are currently being undertaken. In this sense, the status of the field can be compared to neuropsychological development: a more mature understanding of emotion will undoubtably emerge from the growing collaboration between various fields of inquiry.
Some of the research described in this chapter was conducted as part of the requirements for a doctoral dissertation that was submitted to the University of Chicago, December, 1986. I gratefully acknowledge support from an NIMH Training Grant to the Committee on Biopsychology, an NIMH National Research Service Award, and a grant from the Spencer Foundation to Jerre Levy. I thank Marie T. Banich, Joan C. Borod, Zanvel Klein, Bennett L. Leventhal, and Don M. Tiacker for extremely helpful comments on earlier drafts of this chapter. The thoughtful comments of four anonymous reviewers regarding a related paper were also much appreciated. I am indebted to Edwin H. Cook, Robert A. Butler,