MOTOR CONTROL--TONIC NECK AND VESTIBULOSPINAL R EFLEXES

本实验拟对强直颈的神经基质进行研究， 前庭反射，以尝试并确定如何输出与已知的反射 动力学和适当的空间特性产生于去大脑 猫 重点将放在反射通路的脊髓部分， 将使用电生理学和自然刺激的组合。 颈部强直性反射将由头部旋转引起， 猫或通过身体旋转与头部固定在四肢完整的猫。 前庭反射将由全身倾斜引起。 的组合 正弦俯仰和横滚倾斜将用于确定最有效的 刺激平面，即肌肉或神经元的响应向量， 调查 首先，颈部和前庭反射的反应向量 将确定各种肢体肌肉（EMG记录），以及 不同类型的运动神经元（细胞内记录）。 运动神经 记录也将使我们能够研究去极化的动力学 由颈部旋转引起。 接下来将研究 具有确定的颈部反应的颈和腰固有脊髓神经元 向量。 轴突内注射HRP将用于追踪轴突 分支，和尖峰触发平均，以寻找与 运动神经元 在后一种情况下，记录将来自腹根或 运动神经元 颈部和肢体传入输入到脊髓本体神经元将 也被调查。 Ia抑制性神经元在强直颈中的作用 反射将通过寻找神经元的调制来探索， 识别传入输入。 前庭脊髓反射的目标是 寻找前庭神经核和运动神经元之间的中继神经元。 信号 通过C3-C4脊髓本体神经元和 将研究网状脊髓神经元。 此外，我们会研究 C1-C4中的中间神经元的反应，可能涉及到 颈部运动神经元 一些关于前庭脊髓反射的工作将在 猫与灭活半规管，研究纯耳石的影响。

Experiments are planned to study the neural substrate of tonic neck and vestibular reflexes to try and determine how an output with known reflex dynamics and appropriate spatial properties is produced in decerebrate cats. Emphasis will be on the spinal part of the reflex pathway, and a combination of electrophysiology and natural stimulation will be used. Tonic neck reflexes will be evoked by head rotation in labyrinthectomized cats or by body rotation with the head fixed in labyrinth-intact cats. Vestibular reflexes will be evoked by whole-body tilt. Combinations of sinusoidal pitch and roll tilt will be used to determine the most effective stimulus plane, i.e. the response vector of the muscle or neuron under investigation. At first, response vectors for neck and vestibular reflexes will be determined for a variety of limb muscles (EMG recording), and for different types of motoneurons (intracellular recording). Motoneuron recording will also enable us to study the dynamics of the depolarization evoked by neck rotation. Next will be a study of the connections of cervical and lumbar propriospinal neurons with identified neck response vectors. Intra-axonal HRP injection will be used to trace axonal branching, and spike triggered averaging to look for connections with motoneurons. In the latter case, recording will be from ventral roots or motoneurons. Neck and limb afferent input to propriospinal neurons will also be investigated. The role of Ia inhibitory neurons in the tonic neck reflex will be explored by looking for modulation of neurons with identified afferent input. For vestibulospinal reflexes the goal will be to find relay neurons between vestibular nuclei and motoneurons. Signals relayed to the cervical enlargement by C3-C4 propriospinal neurons and by reticulospinal neurons will be studied. In addition, we will study the responses of interneurons in C1-C4 that could be involved in pathways to neck motoneurons. Some work on vestibulospinal reflexes will be done on cats with inactivated semicircular canals, to study pure otolith effects.