- - - PhD Candidate, Department of Physical Therapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
- - - PhD, Department of Physical Therapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
- - - MD, PhD, Neuroscience Laboratory (Brain, Cognition and Behavior), Department of Neuroscience, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
- - - PhD, Department of Physical Therapy, School of Rehabilitation Sciences, Shiraz University of Medical Sciences, Shiraz, Iran

Background: Quantitative Electroencephalography (qEEG) is a non-invasive method used to quantify electrical activity over the cortex. QEEG provides an accurate temporal resolution of the brain activity, making it a useful tool for assessing cortical function during challenging tasks. Objective: This study aimed to investigate postural adjustments in older adults in response to an external perturbation.Material and Methods: In this observational study, nineteen healthy older adults were involved. A ۳۲-channel qEEG was employed to track alterations in beta power on the electrodes over the two sensory-motor areas. Integrated electromyographic activity (IntEMG) of the leg muscles was evaluated in response to perturbations under predictable and unpredictable conditions. Results: The results indicated higher beta power during late-phase in the Cz electrode in both conditions. IntEMG was significantly greater in the tibialis anterior muscle during both conditions in the CPA epoch. In predictable condition, a positive correlation was found between the beta power over C۴ (r = ۰.۵۶۰, p = ۰.۰۱۳) and C۳ (r = ۰.۴۵۸, p = ۰.۰۴۸) electrodes and tibialis anterior muscle amplitude, and between beta power in C۴ and gastrocnemius amplitude (r = ۰.۵۲۵, p = ۰.۰۲۱). In unpredictable condition, there was a positive correlation between beta power over the C۴ and the tibialis anterior amplitude (r = ۰.۵۸۰, p = ۰.۰۰۹) and also it over the C۳ and the tibialis anterior amplitude (r = ۰.۴۵۲, p = ۰.۰۴۹). Conclusion: Our findings demonstrate that sensorimotor processing occurs in the brain during response to perturbation. Furthermore, cortical activity appeared to be greatest during the recruitment of the muscles upon late-phase in older adults.

Electroencephalography, Brain Activity, Electromyography, Posture