Sarah Garfinkel | The dynamic relationship between body, brain and negative emotion

The brain and body are dynamically coupled to influence emotion and cognition. The physiological dimension to emotional processing is widely recognised, yet relatively poorly understood mechanistically. A series of studies using autonomic, neural and behavioural monitoring will demonstrate links between internal visceral physiology, brain and emotion in healthy controls and patients. One experimental strategy to assess how bodily arousal influences cognitive and emotional processes is to capitalize on naturally-occurring bodily fluctuations, such as cardiovascular rhythmicity. In the cardiac cycle, the strength and timing of individual heartbeats is encoded by bursts of afferent neural activity from arterial baroreceptors to brainstem during systole (ventricular ejection period). In a series of experiments we demonstrate that fear processing varies with the cardiac cycle. Specifically, we show that fear processing is accentuated at systole where amygdala activation is greater to fear faces at systole relative to diastole, an effect that is accentuated in both high anxious individuals and those with good interoceptive accuracy (i.e. can accurately detect when their heart is beating at rest). The interaction between body and brain in relation to subliminal anger cues will also be discussed, as will experiments which investigate important individual differences in interoception. Here, the accuracy with which one can correctly identify when one’s own heart is beating is shown to be dissociable from subjective belief about interoceptive ability. Moreover, we show that individuals with Autistic Spectrum Conditions, who are impaired in emotion processing in self and other, have reduced interoceptive accuracy, while displaying an inflated belief about their own interoceptive aptitude. Together these results highlight the importance of the interaction between peripheral and central mechanisms for understanding emotion. The body-to-brain axis can help shape emotion, and individuals with alterations in affective processing, such as those with anxiety and autism, display alterations in this interoceptive channel, with implications for future therapeutic targets. Finally, by exploiting this exaggeration of fear responding at systole, we provide preliminary evidence to suggest that the efficacy of exposure therapy can be increased by including a cardiac manipulation during spider-exposure in arachnophobias. Together, these experiments highlight the role of cardiovascular responses on the processing of threat, with implications for the physiological mechanisms which can be exploited in order to aid treatment efficacy for anxiety. Finally, we discuss the role of subliminal anger cues