From Towards a Science of Consciousness 3 CogNet Proceedings
Emotional experience is a ubiquitous component of the stream of consciousness, and emotional "qualia" appear to interact with other contents and processes of consciousness in complex ways. Recent research suggests that important functional aspects of emotion can operate nonconsciously (e.g., Öhman, Flykt, and Lundqvist, in press; Öhman and Soares 1994). Scientific and philosophic accounts of consciousness will require an understanding of the role of emotion. Indeed emotional experience may be a critical factor in key philosophic debates within consciousness studies, such as the plausibility of thought experiments on the functional role of phenomenal conscious states (DeLancey 1996). Specification of neural circuitry critical for the conscious experience of emotion may also provide important clues in the search for neural systems upon which other domains of conscious experience are dependent. The three chapters of this section each provide perspectives on the relationships between brain and emotional experience.
Within the first chapter, Kaszniak and colleagues review theory and empirical observations concerning the interrelationships of emotion and consciousness, and distinguish components of emotional experience and their interrelationships. They then examine evidence supporting dissociability of conscious and nonconscious aspects of emotion, and recently proposed theories concerning the neural systems subserving conscious emotional experience (e.g., Damasio 1994, LeDoux 1996). Particular attention is given to the hypothesis that the ventromedial frontal cortex contains neural systems necessary for "the conscious body state characteristic of an emotion" (Damasio 1994). Kaszniak and colleagues describe their own empirical research motivated by this hypothesis, focusing upon the relationships between self-reports of emotional experience and measures of sympathetic autonomic activation in persons with localized ventromedial frontal lobe damage. Although able to accurately rate visual scenes along a dimension of positive to negative emotional "valence," these individuals show a relative lack of differentiation in subjectively experienced emotional arousal. A corresponding lack of skin conductance response differentiation of these scene categories suggests that both sympathetic autonomic response and the experience of emotional arousal (but not emotional valence) are dependent upon the integrity of ventromedial frontal systems. Kaszniak and colleagues conclude that lesion locations among individual patients within their study, and the recent positron emission tomography evidence of Lane et al. (1997, 1998) suggest a particularly important role for the anterior cingulate gyrus in the conscious experience of emotion.
In the second chapter Doug Watt draws attention to a potentially critical role of emotion in consciousness. Rather than viewing emotion as simply another qualia of consciousness, Watt proposes a more fundamental role of emotion in providing a necessary "valence tagging" fundamental to the gating and feature binding functions of consciousness. He views this role as instantiated by connectivity between subcortical affective systems and the hypothesized extended reticular thalamic activating system (ERTAS) subserving a global workspace model of consciousness. Watt makes a case for viewing the three "global state functions" of affect, attention, and executive function as intrinsically interpenetrating in their functional roles and neural architectures. The specifics of neural systems critical for the proposed role of emotion in gating and feature binding are debatable, however Watt's core argument for a "protoqualia" role of emotion in the generation of consciousness stands by itself.
Systematic examination of the neural correlates of conscious emotion is limited by constraints in the noninvasive measurement of human brain physiology. Greater precision provided by invasive approachjes in animal models would be advantageous, however in addition to cautions necessary in making inferences from one species to another (see Griffiths 1997) it has been very difficult to infer the presence of emotional or other conscious states in organisms that do not provide verbal self-reports. In the final chapter of this section, Panksepp and Burgdorf summarize research which they interpret as providing evidence for a primitive form of "laughter" in rats. The ultrasonic chirping-like vocalizations recorded by Panksepp and Burgdorf are shown to occur as a robust response to "tickling" different parts of rats' bodies, and to vary with previous social experience and gender. Panksepp and Burgdorf argue that the neuroscientific study of this phenomenon may help in understanding the neural basis of positive conscious emotional states, such as joy. Preliminary work by the authors has suggested that circuits within the reticular nuclei of the thalamus and mesencephalon are important neural structures in this regard, and that the neurotransmitter glutamate is essential for triggering the response.
The three chapters within this section provide a cross-section of current theoretic formulations and empirical research on emotion and consciousness. Although much remains unknown, the work described makes it clear that the fields of consciousness studies and emotion research have much to contribute to each other.
Damasio, A. R. 1994. Descartes' Error: Emotion, Reason and the Human Brain. New York: G. P. Putnam Sons.
DeLancey, C. 1996. Emotion and the function of consciousness. In Journal of Consciousness Studies 3:492Ð499.
Griffiths, P. E. 1997. What Emotions Really Are: The Problem of Psychological Categories. Chicago: The University of Chicago Press.
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Lane, R. D., E. M. Reiman, B. Axelrod, L. S. Yun, A. Holmes, and G. E. Schwartz. 1998. Neural correlates of levels of emotional awareness: evidence of an interaction between emotion and attention in the anterior cingulate cortex. In Journal of Cognitive Neuroscience 10:525Ð535.
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Öhman, A., A. Flykt, and D. Lundqvist. In press. Unconscious emotion: evolutionary perspectives, psychophysiological data and neuropsychological mechanisms. In R. Lane, L. Nadel, and A. Kaszniak (Eds.), The Cognitive Neuroscience of Emotion. New York: Oxford University Press.
Öhman, A., and J. J. F. Soares. 1994. Unconscious anxiety: Phobic responses to masked stimuli. In Journal of Abnormal Psychology 103:231Ð240.