Scientific Research—Investigation of Human Psychophysiological Stress Response Through Infrared Thermography

Investigation of Human Psychophysiological Stress Response Through Infrared Thermography

Managing the psychological and physiological effects of stress presents a global challenge for healthcare. The negative impact of chronic stress on brain health and cognition has been well defined. Unmanaged stress is also known to mediate the breakdown of other biological functions, such as those associated with the immune and cardiovascular systems. While there are many effective ways to manage stress and treat stress-related disorders, each approach suffers from some critical limitation for effectively confronting the negative health consequences of stress. To address the above referenced limitations, we hypothesized neuromodulation-based approaches to managing stress might provide a viable alternative.

We sought to develop a method for modulating psychophysiological arousal and stress responses by providing electrical signaling waveforms through afferent pathways of cranial nerves to neuromodulatory nuclei in the brainstem. During signal transmission to cortex, incoming sensory signals carried by the trigeminal and facial nerves simultaneously undergo local processing by a series of highly inter-connected structures including nuclei of the reticular activating system (RAS) located in the pons.

Figure 1. TEN significantly modulates a sympathetic skin response and emotional thermoregulation by increasing facial temperatures as indicated by functional infrared thermography.

In Experiment subjects were seated in front of a calibrated infrared thermal imaging camera positioned 1.5 meters from subjects face in a thermally stable testing room maintained at 24 °C. Time-lapsed (30 Hz) infrared images were acquired during the 5 min baseline period, during the 15 min sham or transdermal electrical neurosignaling (TEN) treatment period, and for a recovery period up to 10 min following the termination of treatment. Images were then stored for later offline image analysis. Regions of interest were positioned and tracked on the forehead, cheeks, nose, and chin region of the face. From radiographic datasets the average baseline temperature was calculated for each subject and facial location across the 5 min baseline period.

In the present paper, we tested the hypothesis that neuromodulation employing a high-frequency, pulse-modulated TEN waveform targeting afferents (sensory and proprioceptive) of the right trigeminal nerve (V1/V2 distributions), temporal branch of the facial nerve, and cervical spinal nerves can dampen basal sympathetic tone and alter the psychophysiological and biochemical responses to experimentally induced acute stress. Our observations suggest this neurosignaling approach may be useful for alleviating the psychological, physiological, and biochemical responses to acute stress by exerting an effect on endogenous noradrenergic signaling.

In summary our observations demonstrate that, compared to sham, TEN significantly dampened basal sympathetic tone, significantly decreased tension and anxiety, and significantly suppressed the physiological and biochemical responses to acute stress induction. While further experiments including electrophysiological assays and pharmacological manipulations will be required to test this hypothesis, as well as to investigate the influence of TEN on signaling cascades downstream of the LC and NE, our basic observations have provocative implications for the management of stress and optimization of brain health.

Reference

William J. Tyler, Alyssa M. Boasso, Hailey M., et al. Transdermal neuromodulation of noradrenergic activity suppresses psychophysiological and biochemical stress responses in humans. Scientific Reports. 5(13865):1-17, 2015.