Jenks Vestibular Physiology Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA, USA; Ecole Centrale Lyon, Lyon, France.
Jenks Vestibular Physiology Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA, USA.
Neuroscience. 2018 Nov 21;393:350-365. doi: 10.1016/j.neuroscience.2018.08.025. Epub 2018 Sep 4.
The vestibular system enables humans to estimate self-motion, stabilize gaze and maintain posture, but these behaviors are impacted by neural noise at all levels of processing (e.g., sensory, central, motor). Despite its essential importance, the behavioral impact of noise in human vestibular pathways is not completely understood. Here, we characterize the vestibular imprecision that results from neural noise by measuring trial-to-trial vestibulo-ocular reflex (VOR) variability and perceptual just-noticeable differences (JNDs) in the same human subjects as a function of stimulus intensity. We used head-centered yaw rotations about an Earth-vertical axis over a broad range of motion velocities (0-65°/s for VOR variability and 3-90°/s peak velocity for JNDs). We found that VOR variability increased from approximately 0.6°/s at a chair velocity of 1°/s to approximately 3°/s at 65°/s; it exhibited a stimulus-independent range below roughly 1°/s. Perceptual imprecision ("sigma") increased from 0.76°/s at 3°/s to 4.7°/s at 90°/s. Using stimuli that manipulated the relationship between velocity, displacement and acceleration, we found that velocity was the salient cue for VOR variability for our motion stimuli. VOR and perceptual imprecision both increased with stimulus intensity and were broadly similar over a range of stimulus velocities, consistent with a common noise source that affects motor and perceptual pathways. This contrasts with differing perceptual and motor stimulus-dependent imprecision in visual studies. Either stimulus-dependent noise or non-linear signal processing could explain our results, but we argue that afferent non-linearities alone are unlikely to be the source of the observed behavioral stimulus-dependent imprecision.
前庭系统使人类能够估计自身运动、稳定注视和维持姿势，但这些行为在各级处理过程中（例如，感觉、中枢、运动）都会受到神经噪声的影响。尽管它至关重要，但人类前庭通路中噪声的行为影响尚未完全理解。在这里，我们通过测量相同人类受试者的前庭眼反射 (VOR) 变异性和感知可觉察差异 (JND) 的试验间变异性，来描述神经噪声导致的前庭不精确性，其刺激强度作为函数。我们使用以地球垂直轴为中心的头部绕水平轴的偏航旋转，运动速度范围很广（VOR 变异性为 0-65°/s，JND 峰值速度为 3-90°/s）。我们发现，VOR 变异性从约 1°/s 的座椅速度的 0.6°/s 增加到约 65°/s 的 3°/s；它在大约 1°/s 以下表现出独立于刺激的范围。感知不精确性（“sigma”）从 3°/s 的 0.76°/s 增加到 90°/s 的 4.7°/s。使用改变速度、位移和加速度之间关系的刺激，我们发现速度是我们运动刺激的 VOR 变异性的重要线索。VOR 和感知不精确性都随刺激强度增加而增加，在一系列刺激速度中大致相似，这与影响运动和感知通路的共同噪声源一致。这与视觉研究中不同的感知和运动刺激依赖性不精确性形成对比。要么是刺激依赖性噪声，要么是非线性信号处理可以解释我们的结果，但我们认为，传入的非线性本身不太可能是观察到的行为刺激依赖性不精确性的来源。
