Modulation of Primate Somatosensory Cortical Responses

通过神经生理学实验，我们将确定感觉反应和运动相关活动在三种有目的的手运动中是如何动态变化的。具体目标1是确定是否可以在运动之前检测到体感信号，当感觉门控被认为发生时，以及这种检测是否依赖于先前用来触发运动的刺激的形式。具体目标号2旨在测试视觉反馈增益变化之前、期间和之后的反应增益的变化。具体目标编号3被设计用来测试有关任务的先验信息类型的变化对感觉反应性的调节。每个实验将确定感觉运动皮质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)请求行为改变的感觉刺激如果在运动开始附近出现或者如果之前已经出现过其他躯体感觉刺激，则在改变运动时不太有效；(2)当对目标的运动的视觉反馈的增益突然改变时，感觉反应更好地捆绑在振动刺激中，并且与运动相关的活动与运动运动学更紧密地耦合；以及(3)知道跟踪目标偏离发生在哪里而不是在哪个方向导致抑制被时间锁定到预测的跟踪目标偏离开始的大多数外围输入，虽然知道跟踪目标偏离将在哪个方向上发生，但不知道在哪里(以及何时)将发生跟踪目标偏差，从而导致逐渐增加对某些外围输入的抑制。潜在的中心假设是，外部感觉信息在需要时被用来指导行为，而在多余或竞争时被抑制。这些假说将被检验，使用单电极和可能的多电极阵列来记录清醒猴子的初级躯体感觉、顶叶(5区和7b区)、初级运动和前运动(PMD)皮质的细胞外活动，这些猴子接受过执行手腕运动任务的训练。活动与感官刺激的耦合将通过均值向量分析进行评估。使用多元回归分析，运动运动学将与神经元活动相关联。当中风、创伤性头部损伤、周围神经病和运动障碍后出现感觉障碍时，这三种行为可以用于再训练。通过了解躯体感觉反应在行为过程中如何以及在哪里被改变，缺陷可以更容易地被评估和定位。

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.