Vestibulo-spinal influences on reflex performance

描述（由申请人提供）：姿势反射由各种感觉输入诱发和控制。前庭-脊髓（VS）通路将感觉前庭信号传递到脊髓的广泛区域，在那里它们与运动核相互作用以产生反射运动。前庭-颈反射（vestibulo-collic reflexes，VCR）是姿势反射的一个重要分支，它通过在身体扰动期间重新定向头部来避免潜在的颈部损伤。参与产生VCR的颈部运动核接收来自两个不同VS神经元群体的输入，这两个群体在解剖学上通过向眼神经核的侧支投射的存在或不存在来区分。我们假设，这两个不同的VS人群是重要的，在控制反射性头部运动和反射性凝视转移（结合眼睛和头部）。为了验证这一假设，我们将记录放电行为的VS神经元位于前庭核在反射，自愿和被动的头部运动清醒的松鼠猴。将猴坐在前庭转盘上，并允许其仅在水平半规管平面内产生自主和反射性头部运动的不同组合。当不允许头部相对于身体移动时，将相对于旋转期间的响应来量化自愿和反射性头部移动期间的响应。次级VS神经元将从前庭神经顺向鉴定，并且逆向鉴定为投射到脊髓。投射到眼神经核的VS神经元将通过在其放电行为中存在眼运动相关信号以及通过刺激眼神经核后的逆向激活来识别。这些研究的目的是表征每个VS神经群的信号处理与VCR的不同功能作用。信号处理将被量化并与反射的行为目标相关，以确定每个通路的功能作用。这些研究的结果不仅对我们理解头部运动的感觉运动控制有重要意义，而且也适用于全球所有前庭姿势反射的控制，因为它们的机制可能利用类似的神经处理策略。

DESCRIPTION (provided by applicant): Postural reflexes are evoked and controlled by a variety of sensory inputs. The vestibulo-spinal (VS) pathways carry sensory vestibular signals to widespread regions of the spinal cord where they interact with motor nuclei to produce reflexive movement. The vestibulo-collic reflexes (VCR) are an important subset of postural reflexes that avert potential neck injury by reorienting the head during perturbations of the body. The neck motor nuclei involved in producing the VCR receive input from two distinct populations of VS neurons that are anatomically distinguished by the absence or presence of collateral projections to the oculomotor nucleus. We hypothesize that these two distinct VS populations are important in controlling both reflexive head movements and reflexive gaze shifts (combined eye and head). To test this hypothesis we will record the firing behavior of VS neurons located in the vestibular nuclei during reflexive, voluntary, and passive head movements in the awake squirrel monkey. The monkey will be seated on a vestibular turntable and will be permitted to produce different combinations of voluntary and reflexive head movements only in the plane of the horizontal semicircular canals. Responses during voluntary and reflexive head movements will be quantified with respect to the response during rotations when the head is not permitted to move with respect to the body. Secondary VS neurons will be orthodromically identified from the vestibular nerve and antidromically identified as projecting to the spinal cord. VS neurons projecting to the oculomotor nucleus will be identified by the presence of eye movement related signals in their firing behavior and by antidromic activation following stimulation of the oculomotor nucleus. The goal of these studies is to characterize the signal processing for each of the VS neural populations with respect to the different functional roles of the VCR. The signal processing will be quantified and related to behavioral goals of the reflex to determine functional roles of each pathway. The results of these studies are not only significant to our understanding of the sensory-motor control of head movements but are also globally applicable to the control of all vestibular postural reflexes because their mechanisms likely utilize similar neural processing strategies.