Ecological Momentary Assessment of Head Motion: Toward Normative Data of Head Stabilization

Abstract

Head stabilization is fundamental for balance during locomotion but can be impaired in elderly or diseased populations. Previous studies have identified several parameters of head stability with possible diagnostic value in a laboratory setting. Recently, the ecological validity of measures obtained in such controlled contexts has been called into question. The aim of this study was to investigate the ecological validity of previously described parameters of head stabilization in a real-world setting. Ten healthy subjects participated in the study. Head and trunk movements of each subject were recorded with inertial measurement units (IMUs) for a period of at least 10 h. Periods of locomotion were extracted from the measurements and predominant frequencies, root mean squares (RMSs) and bout lengths were estimated. As parameters of head stabilization, attenuation coefficients (ACs), harmonic ratios (HRs), coherences, and phase differences were computed. Predominant frequencies were distributed tightly around 2 Hz and ACs, HRs, and coherences exhibited the highest values in this frequency range. All head stability parameters exhibited characteristics consistent with previous reports, although higher variances were observed. These results suggest that head stabilization is tuned to the 2 Hz fundamental frequency of locomotion and that previously described measures of head stability could generalize to a real-world setting. This is the first study to address the ecological validity of these measures, highlighting the potential use of head stability parameters as diagnostic tools or outcome measures for clinical trials. The low cost and ease of use of the IMU technology used in this study could additionally be of benefit for a clinical application.

Loss of peripheral vestibular input alters the statistics of head movement experienced during natural self‐motion

“…Recent studies have characterized the statistical structure (e.g. the probability of occurrence, and the spectral frequency content) of head movements occurring during natural activities in both humans and non-human primates (Carriot et al 2014;2017a;Hausamann et al 2019). Importantly, in response to the head movements experienced during natural activities, the vestibular system influences subsequent behaviour via the generation of vestibular reflexes and/or the updating of internal models required for accurate motor control (reviewed in Clark et al 2019;Cullen 2019).…”

“…2014; 2017a; Hausamann et al . 2019). Importantly, in response to the head movements experienced during natural activities, the vestibular system influences subsequent behaviour via the generation of vestibular reflexes and/or the updating of internal models required for accurate motor control (reviewed in Clark et al .…”

Validation of the Intel RealSense T265 for Tracking Natural Human Head Motion

“…For example, virtual and augmented reality (VR and AR) rely on tracking of human head motion to render the appropriate visual scene motion in head-mounted displays. And in a clinical setting, one can compare measures of head movement between normal and patient populations to assist in diagnosis and treatment of sensory, motor, and neurological disorders 2 .…”

“…This method was more versatile, but robust performance was still confined to the laboratory. More recently, microelectromechanical system (MEMS)-based inertial measurement units (IMUs) have become accessible and affordable enough for widespread use, which in turn has allowed measurement of head movements outside the laboratory 2,[9][10][11] .…”

Somatosensory Influence on Platform-Induced Translational Vestibulo-Ocular Reflex in Vertical Direction in Humans

“…During locomotion, the erect, straight-legged gait of humans induces substantial head translations in the vertical plane as well as side-to-side head translations (8,10). These head perturbations have a predominant frequency range of 0.5-5.0 Hz (11)(12)(13). The rotational VOR counteracts head motion by inducing image stabilizing eye rotations during locomotion with latencies as short as 14-18 ms (14,15).…”