MOTOR CONTROL: TONIC NECK AND VESTIBULOSPINAL REFLEXES

计划进行实验以研究紧张性颈椎的神经基质和 前庭反射，尝试并确定如何输出与已知的反射 在去大脑的过程中产生了动力学和相应的空间特性 猫。重点将放在反射通路的脊椎部分，以及 将电生理学和自然刺激相结合。 迷路切除后头旋转可引起紧张性颈部反射 或者通过身体旋转，头部固定在迷宫完好无损的猫身上。 全身倾斜会引起前庭反射。组合 将使用正弦俯仰和滚转倾斜来确定最有效的 刺激平面，即肌肉或神经元在 调查。首先，颈部和前庭反射的反应向量 将被确定为各种肢体肌肉(肌电记录)，以及 不同类型的运动神经元(细胞内记录)。运动神经元 录音还将使我们能够研究去极化的动力学 由脖子旋转引起的。接下来，我们将研究 颈和腰椎固有脊髓神经元的颈部反应 向量。轴突内注射HRP将用于追踪轴突 分支和尖峰触发平均化，以查找与 运动神经元。在后一种情况下，记录将来自前根或 运动神经元。颈部和四肢传入本征脊髓神经元将 也被调查。Ia抑制神经元在紧张性颈椎病中的作用 反射将通过寻找神经元的调制来探索 已标识传入输入。对于前庭脊髓反射，目标将是 目的：寻找前庭核团和运动神经元之间的中继神经元。信号 由C3-C4固有脊髓神经元传递至颈椎膨大 将对网状脊髓神经元进行研究。此外，我们还将研究 C_1-C_4区中间神经元的反应可能参与了 颈部运动神经元。关于前庭脊髓反射的一些工作将在 猫的半规管失活，以研究纯耳石效应。

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.