Modulation of Primate Somatosensory Cortical Responses

通过神经生理学实验，我们将确定在三种有目的的手部运动中，感觉反应和运动相关活动是如何动态改变的。具体目标1是确定当感觉门控被认为发生时，是否可以在运动前检测到体感信号，以及这种检测是否依赖于先前用于触发运动的刺激的模式。具体目标2旨在测试在视觉反馈增益变化之前，期间和之后的响应性增益变化。特定目标3的目的是测试感官反应随着任务的先验信息类型的变化而发生的调节。每个实验都将确定感觉运动皮层神经元活动何时与感觉刺激和运动运动学更紧密地结合在一起。将测试三个假设：(1)要求行为改变的感觉刺激在改变运动时效果较差，如果是在运动开始时出现的，或者其他体感刺激之前出现过，(2)感觉反应更容易被振动刺激所吸引，而运动相关的活动在运动运动学中更紧密地结合在一起，当运动到目标的视觉反馈的增益突然改变时，(3)知道在哪里，但不知道在哪个方向，跟踪目标偏差发生的结果是，大多数外围输入被抑制，这些输入被时间锁定到预测的跟踪目标偏差开始，而知道跟踪目标偏差将在哪个方向发生，但不知道在哪里（以及何时）发生，导致对某些外围输入的抑制逐渐增加。潜在的中心假设是，外部感官信息在需要时被利用来指导行为，当冗余或竞争时被抑制。这些假设将被测试，使用单电极和可能的多电极阵列来记录初级体感，顶叶（区域5和7b），初级运动和前运动（PMd）皮层的细胞外活动，清醒，行为猴子训练完成手腕运动任务。活动与感官刺激的耦合将通过平均向量分析来评估。运动运动学将使用多元回归分析与神经元活动相关联。研究的三种行为可用于卒中、颅脑外伤、周围神经病变和运动障碍后发生感觉障碍的再训练。通过了解在行为过程中体感反应是如何以及在哪里被改变的，可以更容易地评估和定位缺陷。

Through neurophysiological experiments, we will determine how sensory responses and movement-related activity is dynamically altered during three types of purposeful hand movements. Specific Aim number 1 is to determine if somatosensory signals can be detected at times before movements when sensory gating is thought to occur, and if this detection depends on the modality of stimuli previously used to trigger movements. Specific Aim number 2 is designed to test changes in responsiveness gain before, during and after changes in visual feedback gain. Specific Aim number 3 is designed to test the modulation of sensory responsiveness with changes in the type of prior information about the task. Each experiment will determine when sensorimotor cortical neuronal activity is more tightly coupled to sensory stimuli and movement kinematics. Three hypotheses will be tested: that (1) Sensory stimuli requesting behavioral changes are less effective in altering movements if presented near movement onset or if other somatosensory stimuli have been presented previously, that (2) Sensory responses are better entrained to vibratory stimuli and movement-related activity is more tightly coupled to movement kinematics when the gain of visual feedback for movement to targets is abruptly changed, and that (3) Knowing where, but not in which direction, tracking-target deviations occur results, in suppression of most peripheral inputs that are time-locked to predicted tracking- target deviation onset, while knowing in which direction but not where (and thus when) a tracking-target deviation will occur results in a gradual increase the suppression of certain peripheral inputs. The under-lying central hypothesis is that external sensory information is utilized as needed to guide behavior and suppressed when redundant or competitive. These hypotheses will be tested, using single electrodes and possibly multi-electrode arrays to record extracellular activity in the primary somatosensory, parietal (area 5 and 7b), primary motor and premotor (PMd) cortices of awake, behaving monkeys trained to perform wrist movement tasks. Coupling of activity to sensory stimuli will be assessed by mean vector analyses. Movement kinematics will be correlated with neuronal activity using multiple regression analyses. The three behaviors to be studied could be used during retraining when sensory disorders occur following stroke, traumatic head injury, peripheral neuropathy and movement disorders. By understanding how and where somatosensory responsiveness is modified during behavior, deficits can be more readily assessed and localized.