Perception of horizontal head and trunk rotation: modification of neck input following loss of vestibular function

Abstract

Chronic loss of vestibular function modifies the role of neck afferents in human perception of self-motion. We characterized this change by comparing the self-motion perception of patients with chronic vestibular loss (Ps) to that of normal subjects (Ns). Stimuli consisted of sinusoidal horizontal rotations (0.025-0.4 Hz) of the trunk relative to the head (neck stimulation) and/or of the head in space (vestibular stimulation). Perception of head rotation relative to the trunk, of trunk rotation in space, or of head rotation in space was assessed in terms of gain and phase (veridical perception, G = 1 and phi = 0 degree) as well as detection threshold using a pointing procedure. (1) Perception of head rotation relative to the trunk (neck proprioception). Ps' detection threshold of head-to-trunk rotation was normal (i.e. similar to that of Ns) across all frequencies tested. Also, with peak angular velocities above 5 degrees/s, the gain of their perception was approximately normal. When peak velocity was decreased below this value, however, either by lowering stimulus frequency with peak displacement kept constant (+/- 8 degrees) or by decreasing peak displacement at constant frequency (0.05 Hz), the gain increased above unity, unlike in Ns. In contrast, the phase remained normal (approximately 0 degree). (2) Perception of trunk rotation in space. Ps perceived their trunks as stationary during neck stimulation and all vestibular-neck combinations at medium to low frequencies. At 0.4 Hz, however, Ps consistently perceived the trunk rotation, conceivably due to somatosensory self-motion cues arising from high body acceleration. In contrast, Ns perceive a trunk-in-space rotation with the neck stimulation and most of the stimulus combinations across the whole frequency range tested. Ns perceived their trunks as stationary only during head rotation on the stationary trunk (presumed to reflect a mutual cancellation of neck and vestibular signals). (3) Perception of head rotation in space. In Ps, unlike Ns, this perception always resembled that of head rotation relative to the trunk. (4) When Ps were presented with a visual or somatosensory space reference (not motion cues), their perception of trunk and head rotation in space became approximately normal. (5) We suggest that there are basically two changes in the neck-induced self-motion perception associated with chronic vestibular loss. First, neck proprioception shows a non-linear gain that overemphasizes low stimulus velocities, for unknown reasons.(ABSTRACT TRUNCATED AT 400 WORDS)

Recovery of Vestibular Ocular Reflex Function and Balance Control after a Unilateral Peripheral Vestibular Deficit

“…Although evidence has been presented that such upregulation occurs for well compensated neurectomy patients (Peterka et al, 2011) there is no evidence to date that such upregulation occurs for UVN patients. Nonetheless, based on recent neurophysiological studies on monkeys (Sadeghi et al, 2011), it can be assumed that such upregulation occurs with UVN patients, just as has been observed in bilateral loss subjects (Schweigart et al, 1993). …”

Proprioceptive contribution of postural control as assessed from very slow oscillations of the support in healthy humans

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“…The anterior and posterior semicircular canals detecting pitch and roll rotations are known to play a particularly important role in the detection of fast postural sways, but not low frequency sways such as those occurring during quiet stance [5,6]. The threshold level at which the vestibular detection of sway is possible on the pitch plane is around the AE18/s reported to be the threshold value at which the conscious perception of pitch motion occurs [7][8][9][10]. In fact, according to Henn et al [11], the threshold value at which angular acceleration detection occurs is approximately 0.28/s 2 .…”

Multimodal Integration After Unilateral Labyrinthine Lesion: Single Vestibular Nuclei Neuron Responses and Implications for Postural Compensation

“…Notably, VO neurons also send their projections to higher brain centers such as thalamus and vestibular cortical areas (Marlinski and McCrea 2008a,b), as well as to the spinal cord. The neck inputs that are unmasked after lesion could potentially contribute to the improvement in spatial orientation reported in patients during combined vestibular/neck proprioceptive stimulation (Schweigart et al 1993). …”