Consistency in physiological stress responses and electromyographic activity during induced stress exposure in women and men

Textile integrated contactless EMG sensing for stress analysis

Stress has become an important issue in today's society. Forty to fifty percent of the work related illnesses are directly or indirectly related to stress. In the ConText project, a biofeedback shirt for daily use is being developed to register muscle activity. The user receives feedback about muscle fatigue and/or the level of stress in order to lower the risk on musculoskeletal disorders. Comfort is an important factor to lower the acceptance threshold to wear the shirt. To achieve optimal comfort, the project aims for unobtrusive measurements with contactless sensors which are textile integrated. Working with contactless sensors induces new challenges for instance the displacement of the sensor in the shirt relative to the anatomical position of the muscles. This could affect the recorded signal and lead to errors in the signal. In this paper, we present the results of the quantification of this misalignment. Secondly, we present the first tests with the embroidered sensor.

The organisation of the stress response, and its relevance to chiropractors: a commentary

The stress response is a natural reaction by the body, against potentially harmful stimuli to enhance the chance for survival. Persistent activation of the stress response can cause changes to homeostatic mechanisms. The study of stress neurophysiology, in the evaluation of the manifestation of disease in the body, suggests that these chronic changes have detrimental effects on sub cortical structures. Furthermore, there is much scientific support for the notion that chronic activation of supraspinal systems will lead to maladaptation of homeostatic mechanisms, causing the impairment of processes within the body, and ultimately leading to visceral disorders. The chiropractic profession for many years has alluded to chronic change of neurophysiological pathways as a potential explanation of visceral disorders, but the profession has typically described these in terms of somatovisceral or viscerosomatic reflex activity. Change in supraspinal neurophysiological efferent activity is increasingly being used to explain "stress" related disease. The chiropractic profession should consider investigating such stress responses by conducting spinal manipulative therapy trials that evaluate supraspinal effects of manipulation. Such research may help elucidate key mechanisms associated with the change of visceral disorders noted by some chiropractors following manipulative therapy.

Norepinephrine differentially modulates different types of respiratory pacemaker and nonpacemaker neurons

Pacemakers are found throughout the mammalian CNS. Yet, it remains largely unknown how these neurons contribute to network activity. Here we show that for the respiratory network isolated in transverse slices of mice, different functions can be assigned to different types of pacemakers and nonpacemakers. This difference becomes evident in response to norepinephrine (NE). Although NE depolarized 88% of synaptically isolated inspiratory neurons, this neuromodulator had differential effects on different neuron types. NE increased in cadmium-insensitive pacemakers burst frequency, not burst area and duration, and it increased in cadmium-sensitive pacemakers burst duration and area, but not frequency. NE also differentially modulated nonpacemakers. Two types of nonpacemakers were identified: "silent nonpacemakers" stop spiking, whereas "active nonpacemakers" spontaneously spike when isolated from the network. NE selectively induced cadmium-sensitive pacemaker properties in active, but not silent, nonpacemakers. Flufenamic acid (FFA), a blocker of ICAN, blocked the induction as well as modulation of cadmium-sensitive pacemaker activity, and blocked at the network level the NE-induced increase in burst area and duration of inspiratory network activity; the frequency modulation (FM) was unaffected. We therefore propose that modulation of cadmium-sensitive pacemaker activity contributes at the network level to changes in burst shape, not frequency. Riluzole blocked the FM of isolated cadmium-insensitive pacemakers. In the presence of riluzole, NE caused disorganized network activity, suggesting that cadmium-insensitive pacemakers are critical for rhythm generation. We conclude that different types of nonpacemaker and pacemaker neurons differentially control different aspects of the respiratory rhythm.