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From the heart – autonomic regulation of the body and emotion
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Abstracts / Autonomic Neuroscience: Basic and Clinical 177 (2013) 1–65
(School of Medicine, University of Western Sydney, Australia; Neuroscience Research Australia) Purpose: Over the past decade, employing sinusoidal galvanic vestibular stimulation (GVS) we demonstrated potent modulation of muscle sympathetic nerve activity (MSNA) and skin sympathetic nerve activity (SSNA). However, GVS affects the discharge of afferents from the entire vestibular apparatus. Here we seek to differentiate between the vestibular organs, by employing specific physiological stimuli. We tested the hypothesis that linear acceleration in the horizontal plane, which targets the utricle exclusively, will evoke vestibulosympathetic reflexes to skin but not to muscle. Methods: MSNA (n = 12) and SSNA (n = 11) were recorded via tungsten microelectrodes inserted into the peroneal nerve. Subjects were seated vertically on a motorised platform and slow sinusoidal accelerations-decelerations (~ 4 mG) were applied in the X and Y direction at 0.08 Hz; respiration, blood pressure and skin blood flow were also recorded. Results: Most subjects did not feel the motion of the platform and those who did could not identify the direction. Cross-correlation analysis revealed potent sinusoidal modulation of both MSNA & SSNA. Modulation of MSNA (32 ± 3% and 29 ± 3% for the X and Y directions) was significantly weaker than that of SSNA (97 ± 3% and 91 ± 5%). Conclusions: We conclude that selective activation of the vestibular utricle causes a pronounced modulation of MSNA and, especially, SSNA. For each sinusoidal cycle there were two major peaks of modulation – one associated with acceleration as the platform moved forward (or right) and one associated with acceleration in the opposite direction (left). We interpret these observations as reflecting inertial displacement of the stereocilia within the utricle during acceleration, causing robust vestibulosympathetic reflexes that contribute to the control of blood pressure and skin blood flow. doi:10.1016/j.autneu.2013.05.061
Abstract 14.7 Comparison of sudoscan and cardiovascular testing for assessment of cardiovascular autonomic neuropathy A. Pavy Le Traon (University hospital of Toulouse, Toulouse, France; INSERM U 1048, Eq 8, Toulouse, France), A. Gerdelat-Mas (University hospital of Toulouse, Toulouse, France), H. Hanaire (University hospital of Toulouse, Toulouse, France), J.M. Senard (University hospital of Toulouse, Toulouse, France; INSERM U 1048, Eq 8, Toulouse, France) Despite its frequency autonomic neuropathy is often poorly investigated. Cardiovascular Autonomic Neuropathy (CAN) has been shown to be one risk factor of morbi-mortality in some populations such as diabetic patients. Sympathetic C-fibers innervating sweat glands can be impaired early and measurement of sweat function has been suggested for early assessment of autonomic dysfunction. SUDOSCAN, a quick, non-invasive method to assess sudomotor function, based on an electrochemical reaction between sweat chloride and stainless-steel electrodes, was compared to usual methods for CAN investigation. 130 patients (mean age: 60.5 ± 13.2 y) addressed for autonomic assessment in various diseases (suspected small fiber neuropathy, parkinsonian syndromes,..) were investigated using Ewing tests and Heart Rate Variability (HRV). CAN severity was defined according to the “Ewing Score” (ES) based on HR variations during controlled breathing, stand
test and Valsalva maneuver, BP variations during orthostatic and hand grip tests. LF (Low Frequency) and HF (High Frequency) power (HRV) considered to respectively reflect sympathetic and parasympathetic tone, were calculated in supine position and in a +75° tilt test. The SUDOSCAN device measures the Electrochemical Sweat Conductance (ESC) of the hands and feet in microSiemens (μS). A risk score for CAN is calculated from these conductances. For a cut-off value of 40μS for hand and foot ESC the OR for having mild dysautonomia or confirmed autonomic failure (Ewing score N1 vs others) were 14.0 [3.1-63.5] and 15.5 [1.9-123.0] respectively and for a cut-off value of 60 μS they were 2.5 [1.2-5.2] and 6.4 [2.4-17.0] respectively. These preliminary results suggest that SUDOSCAN allowing quick and quantitative assessment of sudomotor function may be an interesting tool for CAN detection. This has to be confirmed in a larger population.
doi:10.1016/j.autneu.2013.05.062
Abstract 15.2 From the heart – autonomic regulation of the body and emotion M.A. Gray (Centre for Advanced Imaging, Australia), S.N. Garfinkel (Clinical Imaging Sciences Centre, United Kingdom), A. Achaibou (Affective Cognitive Neuroscience Lab, USA), H.D. Critchley (Clinical Imaging Sciences Centre, UK) The mind is embodied, and much of mental activity, including cognitive, emotional and executive processing, interacts with the control of internal physiological state. Our recent experimental work examines the co-ordination of physiological state with cognitiveemotional processing in the context of cardiovascular control and afferent feedback. In addition to brainstem reflex loops, baroreceptor afferents generated within each cardiac cycle also impact on limbic and paralimbic function. Our recent studies examine central representation of cardiac afferent signals, and the scope of their influence on the CNS via the brief presentation of experimental stimuli at differing phases of the cardiac cycle, thereby allowing for a differential influence of phasic baroreceptor afferent signals. Consistent with effects on surprising stimuli on baroreceptor-MSNA interactions, we observed an attenuation of cardiovascular arousal responses to pain at systole, and reflected by differential neural response within brainstem, insula and amygdala. We followed this by examining cardiac cycle influences on nociception. Probabilistic cuing of electrical skin stimuli reproduced the expected augmentation of pain evoked potential amplitudes. This effect was abolished when pain was delivered at systole, suggesting an interaction of attentionexpectation and baroreceptor gating of nociceptive stimuli. In a following study, we examined how fear conditioning and extinction may be influenced by cardiac afferents. We observed a more rapid extinction of fear conditioned responses when threat stimuli were presented at systole, and corresponding deactivation in thalamic and amygdala regions. Finally we examined subjective emotional appraisal to brief facial stimuli during a speeded reaction time task. Our results suggest that both cardiac alterations supporting speeded responding, and the perceived intensity of specific emotional expressions (disgust and happiness) were influenced by cardiac timing of brief experimental stimuli. These results extend understanding of the scope of cardiac afferent influences, and further demonstrate subtle interactions between physiological regulation and cognitive - emotional processing.
doi:10.1016/j.autneu.2013.05.063
Abstracts / Autonomic Neuroscience: Basic and Clinical 177 (2013) 1–65
(School of Medicine, University of Western Sydney, Australia; Neuroscience Research Australia) Purpose: Over the past decade, employing sinusoidal galvanic vestibular stimulation (GVS) we demonstrated potent modulation of muscle sympathetic nerve activity (MSNA) and skin sympathetic nerve activity (SSNA). However, GVS affects the discharge of afferents from the entire vestibular apparatus. Here we seek to differentiate between the vestibular organs, by employing specific physiological stimuli. We tested the hypothesis that linear acceleration in the horizontal plane, which targets the utricle exclusively, will evoke vestibulosympathetic reflexes to skin but not to muscle. Methods: MSNA (n = 12) and SSNA (n = 11) were recorded via tungsten microelectrodes inserted into the peroneal nerve. Subjects were seated vertically on a motorised platform and slow sinusoidal accelerations-decelerations (~ 4 mG) were applied in the X and Y direction at 0.08 Hz; respiration, blood pressure and skin blood flow were also recorded. Results: Most subjects did not feel the motion of the platform and those who did could not identify the direction. Cross-correlation analysis revealed potent sinusoidal modulation of both MSNA & SSNA. Modulation of MSNA (32 ± 3% and 29 ± 3% for the X and Y directions) was significantly weaker than that of SSNA (97 ± 3% and 91 ± 5%). Conclusions: We conclude that selective activation of the vestibular utricle causes a pronounced modulation of MSNA and, especially, SSNA. For each sinusoidal cycle there were two major peaks of modulation – one associated with acceleration as the platform moved forward (or right) and one associated with acceleration in the opposite direction (left). We interpret these observations as reflecting inertial displacement of the stereocilia within the utricle during acceleration, causing robust vestibulosympathetic reflexes that contribute to the control of blood pressure and skin blood flow. doi:10.1016/j.autneu.2013.05.061
Abstract 14.7 Comparison of sudoscan and cardiovascular testing for assessment of cardiovascular autonomic neuropathy A. Pavy Le Traon (University hospital of Toulouse, Toulouse, France; INSERM U 1048, Eq 8, Toulouse, France), A. Gerdelat-Mas (University hospital of Toulouse, Toulouse, France), H. Hanaire (University hospital of Toulouse, Toulouse, France), J.M. Senard (University hospital of Toulouse, Toulouse, France; INSERM U 1048, Eq 8, Toulouse, France) Despite its frequency autonomic neuropathy is often poorly investigated. Cardiovascular Autonomic Neuropathy (CAN) has been shown to be one risk factor of morbi-mortality in some populations such as diabetic patients. Sympathetic C-fibers innervating sweat glands can be impaired early and measurement of sweat function has been suggested for early assessment of autonomic dysfunction. SUDOSCAN, a quick, non-invasive method to assess sudomotor function, based on an electrochemical reaction between sweat chloride and stainless-steel electrodes, was compared to usual methods for CAN investigation. 130 patients (mean age: 60.5 ± 13.2 y) addressed for autonomic assessment in various diseases (suspected small fiber neuropathy, parkinsonian syndromes,..) were investigated using Ewing tests and Heart Rate Variability (HRV). CAN severity was defined according to the “Ewing Score” (ES) based on HR variations during controlled breathing, stand
test and Valsalva maneuver, BP variations during orthostatic and hand grip tests. LF (Low Frequency) and HF (High Frequency) power (HRV) considered to respectively reflect sympathetic and parasympathetic tone, were calculated in supine position and in a +75° tilt test. The SUDOSCAN device measures the Electrochemical Sweat Conductance (ESC) of the hands and feet in microSiemens (μS). A risk score for CAN is calculated from these conductances. For a cut-off value of 40μS for hand and foot ESC the OR for having mild dysautonomia or confirmed autonomic failure (Ewing score N1 vs others) were 14.0 [3.1-63.5] and 15.5 [1.9-123.0] respectively and for a cut-off value of 60 μS they were 2.5 [1.2-5.2] and 6.4 [2.4-17.0] respectively. These preliminary results suggest that SUDOSCAN allowing quick and quantitative assessment of sudomotor function may be an interesting tool for CAN detection. This has to be confirmed in a larger population.
doi:10.1016/j.autneu.2013.05.062
Abstract 15.2 From the heart – autonomic regulation of the body and emotion M.A. Gray (Centre for Advanced Imaging, Australia), S.N. Garfinkel (Clinical Imaging Sciences Centre, United Kingdom), A. Achaibou (Affective Cognitive Neuroscience Lab, USA), H.D. Critchley (Clinical Imaging Sciences Centre, UK) The mind is embodied, and much of mental activity, including cognitive, emotional and executive processing, interacts with the control of internal physiological state. Our recent experimental work examines the co-ordination of physiological state with cognitiveemotional processing in the context of cardiovascular control and afferent feedback. In addition to brainstem reflex loops, baroreceptor afferents generated within each cardiac cycle also impact on limbic and paralimbic function. Our recent studies examine central representation of cardiac afferent signals, and the scope of their influence on the CNS via the brief presentation of experimental stimuli at differing phases of the cardiac cycle, thereby allowing for a differential influence of phasic baroreceptor afferent signals. Consistent with effects on surprising stimuli on baroreceptor-MSNA interactions, we observed an attenuation of cardiovascular arousal responses to pain at systole, and reflected by differential neural response within brainstem, insula and amygdala. We followed this by examining cardiac cycle influences on nociception. Probabilistic cuing of electrical skin stimuli reproduced the expected augmentation of pain evoked potential amplitudes. This effect was abolished when pain was delivered at systole, suggesting an interaction of attentionexpectation and baroreceptor gating of nociceptive stimuli. In a following study, we examined how fear conditioning and extinction may be influenced by cardiac afferents. We observed a more rapid extinction of fear conditioned responses when threat stimuli were presented at systole, and corresponding deactivation in thalamic and amygdala regions. Finally we examined subjective emotional appraisal to brief facial stimuli during a speeded reaction time task. Our results suggest that both cardiac alterations supporting speeded responding, and the perceived intensity of specific emotional expressions (disgust and happiness) were influenced by cardiac timing of brief experimental stimuli. These results extend understanding of the scope of cardiac afferent influences, and further demonstrate subtle interactions between physiological regulation and cognitive - emotional processing.
doi:10.1016/j.autneu.2013.05.063