Neural Integration of Eye and Head Movements

描述（由申请人提供）：研究计划的长期目标是了解多个运动系统的神经整合。动眼肌系统长期以来一直是研究运动神经控制的一个模型。然而，在自然环境中，定向反应由多个动眼肌和骨骼运动动作组合而成，形成一个复杂而协调的运动。科学研究理想的综合行动是协调的眼-头运动，因为它建立在我们对动眼肌系统的先进知识的基础上。该研究对由动眼肌、前庭和颈椎疾病引起的空间定向缺陷也有诊断价值。

DESCRIPTION (provided by applicant): The long-term objective of the research program is to understand the neural integration of multiple motor systems. The oculomotor system has long served as a model for the study of neural control of movement. In the natural environment, however, an orienting response consists of multiple oculomotor and skeletomotor actions combined to form a complex yet coordinated movement. An integrated action ideal for scientific investigation is a coordinated eye-head movement because it builds on our advanced knowledge of the oculomotor system. The research also offers diagnostic value for spatial orientation deficits resulting from oculomotor, vestibular and cervical disorders. Recent experiments suggest that familiar oculomotor structures, such as the superior colliculus (SC) and pontomedullary reticular formation (PMRF), output a motor command to displace the line of sight (gaze shift) by a desired amplitude and direction. The gaze shift can be executed as a coordinated eye-head movement, implying that the outputs of these oculomotor structures also control premotor circuits that innervate the neck muscles. An association between neural discharge and extraocular motor neurons is demonstrated by recording activity during head-restrained saccades. In contrast, a relationship between spikes and neck motor neurons is only inferred by observing activity during coordinated eye-head movements. A direct evaluation of the activity with head movements has not been performed yet because, under ordinary circumstances, the eye and head components of the coordinated movement are temporally correlated. Hence, four specific aims are proposed to characterize activity and identify neurons associated with head movement control. Using behavioral tasks developed to temporally uncouple head movements from saccadic eye movements, SC neurons will be recorded for head movement related activity, both when no gaze shift is required (Specific Aim 1) and when a gaze shift is planned or being executed (Specific Aim 2). Similar manipulations will be employed to investigate the distribution of PMRF neurons that encode eye-only, head-only and coordinated eye-head movements (Specific Aim 3). Finally, anatomical techniques will be used to determine whether SC neurons send divergent axon collaterals or segregated projections to the eye and head control regions of PMRF (Specific Aim 4).