Sadeghi Soroush G, Mitchell Diana E, Cullen Kathleen E
Department of Physiology, McGill University, 3655 Prom. Sir William Osler, room 1218, Montreal, QC H3G 1Y6, Canada.
Exp Brain Res. 2009 May;195(1):45-57. doi: 10.1007/s00221-009-1751-3. Epub 2009 Mar 13.
The integration of neck proprioceptive and vestibular inputs underlies the generation of accurate postural and motor control. Recent studies have shown that central mechanisms underlying the integration of these sensory inputs differ across species. Notably, in rhesus monkey (Macaca mulata), an Old World monkey, neurons in the vestibular nuclei are insensitive to passive stimulation of neck proprioceptors. In contrast, in squirrel monkey, a New World monkey, stimulation produces robust modulation. This has led to the suggestion that there are differences in how sensory information is integrated during self-motion in Old versus New World monkeys. To test this hypothesis, we recorded from neurons in the vestibular nuclei of another species in the Macaca genus [i.e., M. fascicularis (cynomolgus monkey)]. Recordings were made from vestibular-only (VO) and position-vestibular-pause (PVP) neurons. The majority (53%) of neurons in both groups were sensitive to neck proprioceptive and vestibular stimulation during passive body-under-head and whole-body rotation, respectively. Furthermore, responses during passive rotations of the head-on-body were well predicted by the linear summation of vestibular and neck responses (which were typically antagonistic). During active head movement, the responses of VO and PVP neurons were further attenuated (relative to a model based on linear summation) for the duration of the active head movement or gaze shift, respectively. Taken together, our findings show that the brain's strategy for the central processing of sensory information can vary even within a single genus. We suggest that similar divergence may be observed in other areas in which multimodal integration occurs.
颈部本体感觉输入与前庭输入的整合是产生精确姿势和运动控制的基础。最近的研究表明，这些感觉输入整合的中枢机制在不同物种间存在差异。值得注意的是，在旧世界猴恒河猴（猕猴）中，前庭核中的神经元对颈部本体感受器的被动刺激不敏感。相比之下，在新世界猴松鼠猴中，刺激会产生强烈的调制作用。这表明在旧世界猴和新世界猴的自我运动过程中，感觉信息的整合方式存在差异。为了验证这一假设，我们记录了猕猴属另一个物种（即食蟹猴）前庭核中的神经元活动。记录对象为仅前庭（VO）神经元和位置-前庭-暂停（PVP）神经元。在头下身体被动旋转和全身旋转过程中，两组中的大多数神经元（53%）分别对颈部本体感觉和前庭刺激敏感。此外，身体上头部被动旋转期间的反应可以通过前庭反应和颈部反应的线性总和（通常是拮抗的）得到很好的预测。在主动头部运动期间，VO神经元和PVP神经元的反应在主动头部运动或注视转移期间分别进一步减弱（相对于基于线性总和的模型）。综上所述，我们的研究结果表明，即使在同一属内，大脑对感觉信息进行中枢处理的策略也可能不同。我们认为，在发生多模态整合的其他区域可能也会观察到类似的差异。
