Electroencephalographic Correlates of Continuous Postural Tasks of Increasing Difficulty

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Cortical control of posture is established, but the role of non-visual sensory inputs is not fully understood.
• Parietal cortical regions are linked to vestibulo-spatial functions, yet their precise localization during balance tasks requires further investigation.

Purpose of the Study:

• To investigate the topographical localization of cortical activity during continuous balance tasks using electroencephalography (EEG).
• To analyze spectral power and coherence in theta and alpha bands across specific electrode positions.
• To explore the relationship between task difficulty, subjective ratings, and cortical activity.

Main Methods:

• Electroencephalography (EEG) was recorded from 32 electrodes in 24 healthy individuals performing continuous balance tasks of increasing difficulty.
• Analysis focused on spectral power and coherence in theta (4-8 Hz) and alpha (8-12 Hz) bands at key sensory and motor regions of interest (C3, Cz, C4, P3, P4).
• Balance tasks included bipedal and unipedal stances, with a seated, eyes-closed condition as a control.

Main Results:

• Alpha power decreased significantly as balance task difficulty increased, correlating with subjective difficulty ratings.
• Alpha coherence between C3-Cz-C4 electrode pairs increased with task difficulty.
• Hemispheric asymmetry was observed, with greater reductions in theta and alpha power in right-sided cortical areas, suggesting a role for the non-dominant hemisphere in online postural monitoring.

Conclusions:

• Bilateral central and parietal cortices are functionally important for continuous balance control.
• Observed hemispheric asymmetry indicates the non-dominant hemisphere's involvement in online monitoring during postural tasks.
• Findings suggest active balance control mechanisms rather than simple sensory processing or reflex activation.