Downward gazing behavior after stroke can enhance postural control even in the absence of visual input

 Because I walk on rough paths in the woods I downward gaze all the time to ensure my feet land in safe spaces. 

Didn't this from May 2023 already answer this question? Or is everyone in stroke so fucking incompetent they know nothing of earlier research? 

Older adults and stroke survivors are steadier when gazing down May 2023

Downward gazing behavior after stroke can enhance postural control even in the absence of visual input

Yogev Koren^1*Simona Bar-Haim²Noy Goldhamer^1,3Lior Shmuelof¹

• ¹Department of Cognitive and Brain Sciences, Ben-Gurion University of the Negev, Be’er-Sheva, Israel
• ²Department of Physical-Therapy, Ben-Gurion University of the Negev, Be’er-Sheva, Israel
• ³The Lillian and David E. Feldman Research Center for Rehabilitation Sciences, Adi Negev-Nahalat Eran Medical Center, Ofakim, Israel

Background: Recent reports have revealed that downward gazing, a common behavior among persons with stroke, enhances postural control. The mechanism underlying this phenomenon is currently unknown. In this study, we attempt to provide evidence to support the hypothesis that this effect is primarily derived from altered retinal input caused by gazing down. We also hypothesized that the effect of downward gazing on sway will be more pronounced in subjects with impaired balance control following stroke.

Methods: We quantified standing postural sway of 20 healthy participants and 20 persons with stroke who were instructed to stand as still as possible under different conditions: while gazing forward and gazing down, with their eyes open and eyes closed.

Results: Both the horizontal gaze angle and the lack of visual input had a negative effect on participants’ ability to attenuate their body sway. Yet, the effect of gaze angle was constant regardless of the presence or absence of visual input. Also, people with stroke were more sensitive to the effect of gaze angle.

Discussion: The results of this study indicate that downward gazing enhances postural control even in the absence of visual input and do not support our main hypothesis. Nonetheless, the effect of downward gazing on postural control was greater in unstable people (persons with stroke) than that observed in healthy adults, supporting our secondary hypothesis, which might explain less stable individuals’ tendency to gaze down while walking.

1 Introduction

It is generally accepted that somatosensory, vestibular and visual information are integrated and used to control posture (1). That is, these sensory modalities provide information about the body’s position and motion that is used to generate corrective responses to gravitational and other internal and external forces acting on the body. Given that the visual and vestibular organs are in the head, and that sensory information from the muscles controlling eyes and neck have been implicated in postural control (2), any change in gaze position can affect the signals provided by these modalities, which in turn, can affect postural control.

Although during daily life activities humans often change their gaze position, gaze behavior during walking is mostly studied in the context of anticipatory stepping control (3). Downward gazing (DWG) while walking is a common clinical observation among persons with stroke (PwS) (4), and in other unstable walkers, but very few investigations were conducted to determine how this gaze behavior affects postural control (2, 4–7). Moreover, observations from these investigations were inconsistent and sometimes conflicting, with various mechanisms proposed to underly the observed effects (5, 6).

Recently, Koren et al. (8) reported that DWG enhanced postural steadiness of standing and walking younger adults. These authors also found a similar effect with older adults and PwS (9), two populations that excessively rely on visual input and are more likely to gaze down while walking (10, 11). Based on previous literature and deductive reasoning, they speculated that DWG enhances postural control primarily through its effect on the visual input [for a comprehensive explanation (see 8)]. In this investigation we attempted to provide evidence to support this speculation. To do so, we tested whether the effect of DWG on postural sway with visual input (eyes open) was different from the effect observed without visual input (eyes closed). Specifically, we hypothesized that the effect of DWG on postural sway with eyes open would be greater than the effect with eyes closed (if such an effect is even observed). In other words, we expected to find a Vision by (gaze) Angle interaction, a prediction that previous reports had not tested directly. We also tested whether the effect of DWG is more pronounced in PwS, as PwS are less stable and tend to rely excessively on visual input. For this purpose, a significant Group by (gaze) Angle interaction was considered as supportive.

More at link.