Date Presented 04/04/19
This is the first study to demonstrate abnormal neurophysiological resting state activity in SOR individuals under task-free. Findings may indicate a fundamental deficiency in brain activity that may underlie the daily difficulties experienced by individuals with SOR. Moreover, the brain activity pattern found validates previous findings associating SOR and pain sensitivity. This study may suggest a new direction for a remedial approach using neurofeedback in individuals with SOR.
Primary Author and Speaker: Tami Bar-Shalita
Contributing Authors: Irit Weissman-Fogel, Yelena Granovsky
PURPOSE: Individuals with sensory over-responsiveness (SOR) perceive daily non-painful stimuli as noxious and demonstrate hyperalgesia and lingering sensation to laboratory experimental pain stimuli. Electroencephalography (EEG) of cortical activity at rest is widely used to explore clinical conditions yet has not been tested in subjects with SOR. This study aims to delineate cortical activity in individuals with SOR during relaxed wakefulness.
DESIGN: Using a convenience sampling, this cross-sectional study included 21 healthy individuals (5 males) ages 18-40 years: The study group comprised of participants identified with SOR; N=9, (2 males), who were referred by occupational therapists. The control group consisted of participants with sensory-normo-responsiveness; N=12, (3 males). No group differences were found for age (study vs. control groups mean ± SD years: 36.0±7.3 vs. 30.3±6.1, respectively, p=0.064).
METHOD: Participants completed the Sensory Responsiveness Questionnaire-Intensity Scale (SRQ-IS), a self-report questionnaire used to identify adults with SMD. Thereafter, a five-minute-long continuous EEG recording was performed during wakefulness, under a task-free condition, while participants were sitting on a recliner and instructed to relax and close their eyes. The EEG signal was recorded using a 32-electrode cap (Easy Cap Q40, FMS Falk Minow Services, Herrsching, Germany) with the Quick Amp EEG system (Brain Products GmbH, Munich, Germany). Data was analyzed offline (Analyzer Software, Brain Products GmbH, Munich, Germany).
RESULTS: Participants with SOR demonstrated a global reduction of the EEG activity, including significantly lower theta (p=0.021) and alpha1 (p=0.044) activity, and faster peak alpha frequency (p=0.032). Further, these participants, with SOR, had different topographical dispersions of alpha1 oscillations. Finally, higher sensory-responsiveness scores were associated with high peak alpha power in the control group, but not in the study group.
CONCLUSION: This study revealed a neurophysiological-marker, not previously reported in the SOR condition, further validating its association with a pro-nociceptive state: Reduced alpha activity is commonly interpreted as an electrophysiological indicator of arousal and sensitivity to pain. The EEG pattern of response found, demonstrating a neurophysiological state of a “non-resting” brain, may partly explain the reported ongoing daily alertness to environmental stimuli in individuals with SOR. Moreover, this study may suggest a new direction for a remedial approach ameliorating cortical activity in individuals with SOR.
References
Granovsky,Y., Weissman-Fogel, I., & Bar-Shalita, T. (2018). Resting-state EEG in individuals with sensory over-responsivity: an exploratory study. American Journal of Occupational Therapy. in press.
Weissman-Fogel, I., Granovsky, Y., & Bar-Shalita T. (2018). Sensory over-responsiveness among healthy subjects is associated with a pro-nociceptive state. Pain Practice 8, (4), 473–486. DOI. 10.1111/papr.12619
