Neurology Department, Neuropsychology Unit, University Hospital of Geneva, Geneva, Switzerland.
Department of Psychology, University of Montréal, Montréal, QC, Canada.
Eur J Neurol. 2021 May;28(5):1779-1783. doi: 10.1111/ene.14701. Epub 2021 Jan 19.
In this study, the question of whether egocentric representation of space is impaired in chronic unilateral vestibulopathies was examined. The objective was to test current theories attributing a predominant role to vestibular afferents in spatial cognition and to assess whether representational neglect signs are common in peripheral vestibular loss.
The subjective straight-ahead (SSA) direction was investigated using a horizontal rod allowing the translation and rotation components of the body midline representation to be dissociated in 21 patients with unilateral vestibular loss (right, 13; left, eight) and in 12 healthy controls.
Compared to the controls, the patients with unilateral vestibulopathy showed a translation bias of their SSA, without rotation bias. The translation bias was not lateralized towards the lesioned side as typically found for biases reported after unilateral vestibular loss. Rather, the SSA bias was rightward whatever the side of the vestibular loss. The translation bias correlated with the vestibular loss, as measured by caloric response and vestibulo-ocular reflex gain, but not with the subjective visual vertical or the residual spontaneous nystagmus.
The present data suggest that the dysfunctions of neural networks involved in egocentred and allocentred representations of space are differentially compensated for in unilateral vestibular defective patients. In particular, they suggest that asymmetrical vestibular inputs to cortical regions lead to representational spatial disturbances as does defective cortical processing of vestibular inputs in spatial neglect after right hemisphere stroke. They also highlight the predominant role of symmetrical and unaltered vestibular inputs in spatial cognition.
本研究旨在探讨慢性单侧前庭病变患者的空间自我中心表征是否受损。目的是检验当前将前庭传入在空间认知中起主要作用的理论，并评估代表性忽视迹象在周围性前庭损失中是否常见。
通过允许身体中线表示的平移和旋转分量分离的水平杆来研究主观直线前进（SSA）方向，研究对象为 21 名单侧前庭丧失患者（右侧 13 例，左侧 8 例）和 12 名健康对照者。
与对照组相比，单侧前庭病变患者的 SSA 表现出平移偏差，而无旋转偏差。平移偏差没有向病变侧偏向，如单侧前庭丧失后报道的偏差那样。相反，无论前庭丧失的哪一侧，SSA 偏差都是向右的。平移偏差与前庭丧失相关，如通过冷热反应和前庭眼反射增益测量，但与主观视觉垂直或残余自发性眼球震颤无关。
目前的数据表明，涉及自我中心和他心空间表示的神经网络功能障碍在单侧前庭缺陷患者中得到了不同程度的补偿。特别是，它们表明，皮质区域不对称的前庭输入会导致空间代表障碍，就像右侧半球中风后皮质处理前庭输入缺陷导致空间忽视一样。它们还突出了对称且未改变的前庭输入在空间认知中的主要作用。
