Neural Integration of Eye and Head Movements

描述(由申请人提供)：该研究计划的长期目标是了解多个运动系统的神经整合。长期以来，眼球运动系统一直是研究神经运动控制的模型。然而，在自然环境中，定向反应由多个眼球运动和骨骼运动动作组成，形成复杂而协调的运动。科学研究的理想综合动作是协调的眼头运动，因为它建立在我们对眼球运动系统的先进知识基础上。这项研究还为眼球运动、前庭和颈椎疾病引起的空间定向缺陷提供了诊断价值。 最近的实验表明，常见的动眼神经结构，如上丘(SC)和桥延髓网状结构(PMRF)，可以输出运动指令，以所需的幅度和方向移位视线(凝视移动)。视线转移可以作为眼头的协调运动来执行，这意味着这些动眼结构的输出也控制着支配颈部肌肉的运动前回路。神经放电和眼外运动神经元之间的联系是通过记录头盔眼跳时的活动来证明的。相比之下，只有通过观察眼头协调运动时的活动，才能推断出棘波和颈部运动神经元之间的关系。由于在正常情况下，协调运动的眼睛和头部成分在时间上是相关的，因此还没有对头部运动的活动进行直接评估。因此，提出了四个特定的目标来表征活动和识别与头部运动控制相关的神经元。使用开发的行为任务将头部运动与眼跳运动暂时分离，SC神经元将被记录用于与头部运动相关的活动，无论是在不需要凝视转移(特定目标1)时，还是在计划或执行凝视转移时(特定目标2)。类似的操作将被用来研究PMRF神经元的分布，这些神经元编码仅限于眼睛、仅限于头部和协调的眼头运动(特定目标3)。最后，解剖学技术将被用来确定SC神经元是否向PMRF的眼和头控制区发送发散轴突侧支或分离投射(特定目标4)。

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).