| 1. |
- Gray, Marcus A, et al.
(författare)
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Following one's heart: cardiac rhythms gate central initiation of sympathetic reflexes.
- 2009
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Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 29:6, s. 1817-25
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Tidskriftsartikel (refereegranskat)abstract
- Central nervous processing of environmental stimuli requires integration of sensory information with ongoing autonomic control of cardiovascular function. Rhythmic feedback of cardiac and baroreceptor activity contributes dynamically to homeostatic autonomic control. We examined how the processing of brief somatosensory stimuli is altered across the cardiac cycle to evoke differential changes in bodily state. Using functional magnetic resonance imaging of brain and noninvasive beat-to-beat cardiovascular monitoring, we show that stimuli presented before and during early cardiac systole elicited differential changes in neural activity within amygdala, anterior insula and pons, and engendered different effects on blood pressure. Stimulation delivered during early systole inhibited blood pressure increases. Individual differences in heart rate variability predicted magnitude of differential cardiac timing responses within periaqueductal gray, amygdala and insula. Our findings highlight integration of somatosensory and phasic baroreceptor information at cortical, limbic and brainstem levels, with relevance to mechanisms underlying pain control, hypertension and anxiety.
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| 2. |
- Gray, Marcus A, et al.
(författare)
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Modulation of emotional appraisal by false physiological feedback during fMRI.
- 2007
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Ingår i: PLoS ONE. - 1932-6203. ; 2:6, s. e546-
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Tidskriftsartikel (refereegranskat)abstract
- James and Lange proposed that emotions are the perception of physiological reactions. Two-level theories ofemotion extend this model to suggest that cognitive interpretations of physiological changes shape self-reported emotions.Correspondingly false physiological feedback of evoked or tonic bodily responses can alter emotional attributions. Moreover,anxiety states are proposed to arise from detection of mismatch between actual and anticipated states of physiologicalarousal. However, the neural underpinnings of these phenomena previously have not been examined. Methodology/Principal Findings. We undertook a functional brain imaging (fMRI) experiment to investigate how both primary and secondorderlevels of physiological (viscerosensory) representation impact on the processing of external emotional cues. 12participants were scanned while judging face stimuli during both exercise and non-exercise conditions in the context of trueand false auditory feedback of tonic heart rate. We observed that the perceived emotional intensity/salience of neutral faceswas enhanced by false feedback of increased heart rate. Regional changes in neural activity corresponding to this behaviouralinteraction were observed within included right anterior insula, bilateral mid insula, and amygdala. In addition, right anteriorinsula activity was enhanced during by asynchronous relative to synchronous cardiac feedback even with no change inperceived or actual heart rate suggesting this region serves as a comparator to detect physiological mismatches. Finally, BOLDactivity within right anterior insula and amygdala predicted the corresponding changes in perceived intensity ratings at botha group and an individual level. Conclusions/Significance. Our findings identify the neural substrates supportingbehavioural effects of false physiological feedback, and highlight mechanisms that underlie subjective anxiety states,including the importance of the right anterior insula in guiding second-order ‘‘cognitive’’ representations of bodily arousalstate.
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