The impact of external and internal focus of attention on visual dependence and EEG alpha oscillations during postural control

Abstract

Background The ability to maintain upright posture requires successful integration of multiple sensory inputs (visual, vestibular, and somatosensory). When one or more sensory systems become unreliable, the postural control system must “down-weight” (or reduce the influence of) those senses and rely on other senses to maintain postural stability. As individuals age, their ability to successfully reweight sensory inputs diminishes, leading to increased fall risk. The present study investigates whether manipulating attentional focus can improve the ability to prioritize different sensory inputs for postural control. Methods Forty-two healthy adults stood on a balance board while wearing a virtual reality (VR) head-mounted display. The VR environment created a multisensory conflict amongst the different sensory signals as participants were tasked with maintaining postural stability on the balance board. Postural sway and scalp electroencephalography (EEG) were measured to assess visual weighting and cortical activity changes. Participants were randomized into groups that received different instructions on where to focus their attention during the balance task. Results Following the instructions to direct attention toward the movement of the board (external focus group) was associated with lower visual weighting and better balance performance than when not given any instructions on attentional focus (control group). Following the instructions to direct attention towards movement of the feet (internal focus group) did not lead to any changes in visual weighting or balance performance. Both external and internal focus groups exhibited increased EEG alpha power (8–13 Hz) activity over the occipital cortex as compared to the control group. Conclusions Current results suggest that directing one’s attention externally, away from one’s body, may optimize sensory integration for postural control when visual inputs are incongruent with somatosensory and vestibular inputs. Current findings may be helpful for clinicians and researchers in developing strategies to improve sensorimotor mechanisms for balance.

The Effect of Sensory Reweighting on Postural Control and Cortical Activity in Parkinson’s Disease

“…The increased alpha power may reflect either impaired central processing of visual cues, or difficulties resolving visual cues from conflicting somatosensory cues. Previous research has shown increased alpha power when the inputs from the visual and somatosensory systems are incongruent in healthy adults 19 . Theta/beta ratio power increased in participants with PD when relying on somatosensory cues 42 .…”

“…Changes in occipital alpha power appear to reflect the sensory and movement-related information processing of postural control 18 . In neurotypical young adults, occipital alpha power increased when standing with the eyes closed 19,20 . Theta/beta ratio power reflects cognitive activity related to attention and working memory processes 21,22 .…”

“…Electroencephalography (EEG) utilizes electrodes placed on the scalp to measure voltage potential differences between two locations on the scalp 15 . The neuronal oscillations captured using EEG can be divided into delta (0 -4 Hz), theta (4 -7 Hz), alpha (8)(9)(10)(11)(12), beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma (>30 Hz) frequency bands. Within these bands, alpha power and the ratio of slow (theta) to fast wave (beta) activity are of particular interest to study the cortical processes of postural control 16,17 .…”

The effects of conscious movement processing on the neuromuscular control of posture

“…For example, based on our results we recommend future research to investigate whether IMC is affected by CMP within the beta band, looking specifically at the SOL-GM and PL-SOL muscle pairs, given that we observed largest effects for these frequencies and muscle pairs (see supplementary data 1). Furthermore, recent work has shown that CMP can alter sensory processing and integration during standing balance tasks (Ma et al, 2022). Future work may explore how IMC is affected by, for instance, multisensory conflict during balance, and what role CMP plays in aggravating or resolving such conflicts.…”

Electroencephalographic interbrain synchronization in children with disabilities, their parents, and neurologic music therapists

“…Following the data decomposition by ICA, we used the ICLabel function in the EEGLab (Delorme & Makeig, 2004) to identify artifactual independent components (Pion-Tonachini et al, 2019). The thresholds of independent components were determined based on previous research (Ma et al, 2022). To ensure reproducibility and to avoid subjective bias, over 80% of artifactual independent components were removed.…”