title: Following one's heart: cardiac rhythms gate central initiation of sympathetic reflexes.
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.
authors.affiliation: Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, East Sussex BN1 9RR, United Kingdom. m.a.gray@bsms.ac.uk
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Gray
authors.forename: Karin
authors.initials: K
authors.lastname: Rylander
authors.forename: Neil A
authors.initials: NA
authors.lastname: Harrison
authors.forename: B Gunnar
authors.initials: BG
authors.lastname: Wallin
authors.forename: Hugo D
authors.initials: HD
authors.lastname: Critchley
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004597:Electroshock / Q000009:adverse effects; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006321:Heart; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D013564:Sympathetic Nervous System / Q000502:physiology*; D055815:Young Adult