Dynamics of Parasympathetic Activity in Violent Incarcerated Offenders Before, During, and in Recovery From An Emotional Inhibition Task

Dynamics of the autonomic nervous system (ANS) are hypothesized to play a role in the emergence of interpersonal violence. In the present study, we examined continuous activities of the inhibitory parasympathetic pathway of the ANS through the root mean square of successive differences between normal heartbeats (RMSSD) in 22 male offenders who committed interpersonal violence and 24 matched controls from the general population across three successive phases: resting baseline, while performing an emotional Go/No-Go task, and post-task recovery. Results showed that across the three phases, the offender group presented lower RMSSD at baseline (pFDR = .003; Cohen’s d = -1.11), but similar levels during the task, attributed to a significant increase in their RMSSD level (pFDR = .027, Cohen’s d = -1.26). During recovery, no distinction between the two groups was found, but although both groups showed signs of recovering toward baseline values. These findings suggest that violent incarcerated offenders can flexibly engage parasympathetic resources to meet environmental challenges. This underscores the necessity of considering parasympathetic dynamics and its respective mobilization/flexibility to better understand ANS profiles underlying interpersonal violence and designed more tailored intervention.

Early phase of pupil dilation is mediated by the peripheral parasympathetic pathway

Pupil diameter fluctuates in association with changes in brain states induced by the neuromodulator systems. However, it remains unclear how the neuromodulator systems control the activity of the iris sphincter (constrictor) and dilator muscles to change the pupil size. The present study compared temporal patterns of pupil dilation during movement when each muscle was pharmacologically manipulated in the human eye. When the iris sphincter muscle was blocked with tropicamide, the latency of pupil dilation was delayed and the magnitude of pupil dilation was reduced during movement. In contrast, when the iris dilator muscle was continuously stimulated with phenylephrine, the latency and magnitude of rapid pupil dilation did not differ from the untreated control eye, but sustained pupil dilation was reduced until the end of movement. These results suggest that the iris sphincter muscle, which is under the control of the parasympathetic pathway, is quickly modulated by the neuromodulator system and plays a major role in rapid pupil dilation. However, the iris dilator muscle receives signals from the neuromodulator system with a slow latency and is involved in maintaining sustained pupil dilation.

Indices of association between anxiety and mindfulness: a guide for future mindfulness studies

Mindfulness and anxiety are often linked as inversely related traits and there have been several theoretical and mediational models proposed suggesting such a relationship between these two traits. The current review report offers an account of self-report measures, behavioral, electrophysiological, hemodynamic, and biological studies, which provide converging evidence for an inverse relationship between mindfulness and anxiety. To our knowledge, there are no comprehensive accounts of empirical evidence that investigate this relationship. After reviewing several empirical studies, we propose a schematic model, where a stressor can trigger the activation of amygdala which activates the hypothalamic–pituitary–adrenal (HPA) pathway. This hyperactive HPA axis leads to a cascade of psychological, behavioral, electrophysiological, immunological, endocrine, and genetic reactions in the body, primarily mediated by a sympathetic pathway. Conversely, mindfulness protects from deleterious effects of these triggered reactions by downregulating the HPA axis activity via a parasympathetic pathway. Finally, we propose a model suggesting a comprehensive scheme through which mindfulness and anxiety may interact through emotion regulation. It is recommended that future mindfulness intervention studies should examine a broad spectrum of measurement indices where possible, keeping logistic feasibility in mind and look at mindfulness in conjunction with anxiety rather than independently.

Electroacupuncture at ST37 Enhances Jejunal Motility via Excitation of the Parasympathetic System in Rats and Mice

Background.The roles of the sympathetic and parasympathetic systems in mediating the effect of electroacupuncture (EA) at ST37 on jejunal motility have yet to be demonstrated.Aim. We used rats and mice to investigate the effect and mechanism of action of EA at ST37 on jejunal motility.Methods.Jejunal motility was recorded by a balloon placed in the jejunum and connected to a biological signal collection system through a transducer. The effects of EA (3 mA) at ST37 were evaluated in Sprague-Dawley rats without drugs and with the administration of clenbuterol, propranolol, acetylcholine, and atropine. Further, the efficacy of EA at different intensities (1/2/4/6/8 mA) was measured in wild-type mice andβ1β2-/-mice andM2M3-/-mice.Results.In Sprague-Dawley rats, the excitatory effect of EA at ST37 on jejunal motility disappeared in the presence of the muscarinic receptor antagonist atropine. EA at ST37 was less effective inM2M3-/-mice than in wild-type mice. Furthermore, to a certain extent, there existed “intensity-response” relationship between jejunal motility and EA.Conclusions.EA at ST37 can enhance jejunal motility in rats and mice mainly via excitation of the parasympathetic pathway. There is an “intensity-response” relationship between EA and effect on jejunal motility.

Electroacupuncture at ST-36 accelerates colonic motility and transit in freely moving conscious rats

Acupuncture is useful for functional bowel diseases, such as constipation and diarrhea. However, the mechanisms of beneficial effects of acupuncture on colonic function have scarcely ever been investigated. We tested the hypothesis that electroacupuncture (EA) at ST-36 stimulates colonic motility and transit via a parasympathetic pathway in conscious rats. Hook-shaped needles were inserted at bilateral ST-36 (lower limb) or BL-21 (back) and electrically stimulated at 10 Hz for 20 min. We also studied c-Fos expression in response to EA at ST-36 in Barrington's nucleus of the pons. EA at ST-36, but not BL-21, significantly increased the amplitude of motility at the distal colon. The calculated motility index of the distal colon increased to132 ± 9.9% of basal levels ( n = 14, P < 0.05). In contrast, EA at ST-36 had no stimulatory effects in the proximal colon. EA at ST-36 significantly accelerated colonic transit [geometric center (GC) = 6.76 ± 0.42, n = 9, P < 0.001] compared with EA at BL-21 (GC = 5.23 ± 0.39, n = 7). The stimulatory effect of EA at ST-36 on colonic motility and transit was abolished by pretreatment with atropine. EA-induced acceleration of colonic transit was also abolished by extrinsic nerve denervation of the distal colon (GC = 4.69 ± 0.33, n = 6). The number of c-Fos-immunopositive cells at Barrington's nucleus significantly increased in response to EA at ST-36 to 8.1 ± 1.1 cells/section compared with that of controls (2.4 ± 0.5 cells/section, n = 3, P < 0.01). It is concluded that EA at ST-36 stimulates distal colonic motility and accelerates colonic transit via a sacral parasympathetic efferent pathway (pelvic nerve). Barrington's nucleus plays an important role in mediating EA-induced distal colonic motility in conscious rats.