CGRP release in an experimental human trigeminal pain model

Background Migraine and trigemino-autonomic cephalalgia attacks are associated with an increase of α-calcitonin-gene related peptide levels in the ipsilateral jugular vein. It is however unknown whether trigeminal pain stimulation in healthy subjects without headache disorders also induces increase of calcitonin-gene related peptide levels. Findings We measured α-calcitonin-gene related peptide levels in eight healthy subjects after subcutaneous injection of capsaicin in the forehead and in the mandibular region and after injection of sodium chloride in the forehead. We observed a significant increase of α-calcitonin-gene related peptide level only after injection of capsaicin in the forehead (i.e. first trigeminal branch). We also observed trigemino-autonomic activation (lacrimation, rhinorrhea etc.) only after injection of capsaicin in the forehead. Conclusion Increase of α-calcitonin-gene related peptide levels do not only occur in primary headache attacks but also after experimental trigeminal pain of the first branch. This finding suggests that α-calcitonin-gene related peptide elevation is, at least an additional, unspecific effect of first trigeminal branch stimulation following pain activation and not a specific mechanism of idiopathic headache disorders.

An investigation of cardiac indices in normal sleepers and those with insomnia disorder

Cardiovascular disease (CVD) is the world’s leading cause of death. Insomnia, a prevalent disorder among Canadian adults, has been identified in some studies as an independent risk factor for CVD. Heart rate variability (HRV), often used as a proxy for autonomic activity in the body, has been demonstrated to be impaired in individuals with insomnia. Scientists have suggested that results implicate exaggerated sympathetic activation in people with insomnia, which can lead to impaired cardiac reactivity and poorer heart health. Much of the research in this field has been with poorly classified clinical groups and potentially confounding comorbid disorders, making the results difficult to interpret. Findings of the present study extend our understanding of the relationship between insomnia and CVD by addressing the weaknesses of prior research and by utilizing contemporary statistical methods. A well-classified clinical group meeting Research Diagnostic Criteria for Insomnia Disorder (ID; N = 26) was compared to normal sleepers (NS; N = 23) on two well-validated indices of cardiovascular health and autonomic activity, cardiac output (CO) and pre-ejection period (PEP). Values of these indices were derived from an acoustic challenge paradigm that allowed the heart to adapt to the environment via autonomic influence. A multi-level modeling (MLM) approach was used to evaluate both the within-person and between-person differences in autonomic activation and cardiac functioning using a group of predictors that are known to be associated with insomnia and/or CVD. Results of the level two MLM analyses revealed that sleep variables are not significantly predictive of cardiac reactivity indices. A post-hoc linear regression analysis using the same predictor variables to predict HRV revealed that insomnia was significantly predictive of HRV. These conflicting results raise important questions about research methodology, validity of chosen indices, and statistical techniques.

An investigation of cardiac indices in normal sleepers and those with insomnia disorder

Cardiovascular disease (CVD) is the world’s leading cause of death. Insomnia, a prevalent disorder among Canadian adults, has been identified in some studies as an independent risk factor for CVD. Heart rate variability (HRV), often used as a proxy for autonomic activity in the body, has been demonstrated to be impaired in individuals with insomnia. Scientists have suggested that results implicate exaggerated sympathetic activation in people with insomnia, which can lead to impaired cardiac reactivity and poorer heart health. Much of the research in this field has been with poorly classified clinical groups and potentially confounding comorbid disorders, making the results difficult to interpret. Findings of the present study extend our understanding of the relationship between insomnia and CVD by addressing the weaknesses of prior research and by utilizing contemporary statistical methods. A well-classified clinical group meeting Research Diagnostic Criteria for Insomnia Disorder (ID; N = 26) was compared to normal sleepers (NS; N = 23) on two well-validated indices of cardiovascular health and autonomic activity, cardiac output (CO) and pre-ejection period (PEP). Values of these indices were derived from an acoustic challenge paradigm that allowed the heart to adapt to the environment via autonomic influence. A multi-level modeling (MLM) approach was used to evaluate both the within-person and between-person differences in autonomic activation and cardiac functioning using a group of predictors that are known to be associated with insomnia and/or CVD. Results of the level two MLM analyses revealed that sleep variables are not significantly predictive of cardiac reactivity indices. A post-hoc linear regression analysis using the same predictor variables to predict HRV revealed that insomnia was significantly predictive of HRV. These conflicting results raise important questions about research methodology, validity of chosen indices, and statistical techniques.

Emotion regulation of others’ positive and negative emotions is related to distinct patterns of heart rate variability and situational empathy

Although emotion regulation has been proposed to be crucial for empathy, investigations on emotion regulation have been primarily limited to intrapersonal processes, leaving the interpersonal processes of self-regulation rather unexplored. Moreover, studies showed that emotion regulation and empathy are related with increased autonomic activation. How emotion regulation and empathy are related at the autonomic level, and more specifically during differently valenced social situations remains an open question. Healthy adults viewed a series of short videos illustrating a target who was expressing positive, negative, or no emotions during a social situation (Positive, Negative, or Neutral Social Scenes). Prior to each video, participants were instructed to reappraise their own emotions (Up-regulation, Down-regulation, or No-regulation). To assess autonomic activation, RR intervals (RRI), high frequency (HF) components of heart rate variability (HRV), and electrodermal activity phasic responses (EDRs) were calculated. Situational empathy was measured through a visual analogue scale. Participants rated how empathic they felt for a specific target. Up- and Down-regulation were related to an increase and a decrease in situational empathy and an increase in RRI and HF, respectively, compared to the control condition (No-regulation). This suggests increased activity of the parasympathetic branch during emotion regulation of situational empathic responses. Positive compared to Negative Social Scenes were associated with decreased situational empathy, in addition to a slightly but non-significantly increased HF. Altogether, this study demonstrates that emotion regulation may be associated with changes in situational empathy and autonomic responses, preferentially dominated by the parasympathetic branch and possibly reflecting an increase of regulatory processes. Furthermore, the current study provides evidence that empathy for different emotional valences is associated with distinct changes in situational empathy and autonomic responses.

0942 Alternating Leg Muscle Activation and Hypnagogic Foot Tremor in Children: Comparative Study of Polysomnographic and Clinico-Demographic Variables

Introduction The clinical and polysomnographic meaning of the Alternating Leg Muscle Activation (ALMA) and Hypnagogic Foot Tremor (HFT) patterns in children is not known. Methods A descriptive study was carried out to identify the prevalence and polysomnographic characteristics of ALMA and HFT sequences in a sample of 122 children sequentially admitted in the sleep laboratory, with the analysis of clinical and demographic characteristics of the ALMA/HFT group in relation to a comparison group without this condition, paired by age and gender. Results Sample prevalence was 14.8% for any HFT/ALMA event, 13.1% for ALMA and 10.7% for HFT. In the HFT/ALMA group, the mean age was 8 years old (2-12 years old), 66.7% of males. Obstructive Sleep Apnea was observed in 75% of children, but HFT / ALMA sequences only occasionally occurred in association with respiratory events. The use of medications with monoaminergic activity was associated with the occurrence of HFT/ALMA, p=0,019. There was higher N1 sleep content in the HFT / ALMA group, p=0,0301. There was no significant difference between both groups regarding the other clinical-demographic or polysomnographic parameters analyzed. Autonomic activation represented by heart rate fluctuations often occurred in association with the HFT / ALMA sequences, irrespective of the occurrence of arousals, awakenings, other motor or respiratory events. Conclusion HFT / ALMA is a frequent condition in children that are referred to the sleep lab.The stereotypy of the HFT / ALMA series suggests that their origin might be motor central pattern generators, which are potentially influenced by substances with monoaminergic effect. The finding of higher superficial sleep content in children with HFT / ALMA may indicate greater susceptibility to alteration of pediatric sleep architecture by such subtle motor events. The possibility of clinical consequences and cardiovascular diseases should be considered in relation to the association of HFT / ALMA with observed autonomic activation. Support None.

Nocturnal swallowing augments arousal intensity and arousal tachycardia

Cortical arousal from sleep is associated with autonomic activation and acute increases in heart rate. Arousals vary considerably in their frequency, intensity/duration, and physiological effects. Sleep and arousability impact health acutely (daytime cognitive function) and long-term (cardiovascular outcomes). Yet factors that modify the arousal intensity and autonomic activity remain enigmatic. In this study of healthy human adults, we examined whether reflex airway defense mechanisms, specifically swallowing or glottic adduction, influenced cardiac autonomic activity and cortical arousal from sleep. We found, in all subjects, that swallows trigger rapid, robust, and patterned tachycardia conserved across wake, sleep, and arousal states. Tachycardia onset was temporally matched to glottic adduction—the first phase of swallow motor program. Multiple swallows increase the magnitude of tachycardia via temporal summation, and blood pressure increases as a function of the degree of tachycardia. During sleep, swallows were overwhelmingly associated with arousal. Critically, swallows were causally linked to the intense, prolonged cortical arousals and marked tachycardia. Arousal duration and tachycardia increased in parallel as a function of swallow incidence. Our findings suggest that cortical feedback and tachycardia are integrated responses of the swallow motor program. Our work highlights the functional influence of episodic, involuntary airway defense reflexes on sleep and vigilance and cardiovascular function in healthy individuals.