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的活动是如何在三种类型的有目的的手部运动过程中动态改变的。 具体目标1是确定当感觉门控被认为发生时，在运动之前的时间是否可以检测到体感信号，以及这种检测是否取决于先前用于触发运动的刺激的模态。 具体目标2旨在测试视觉反馈增益变化之前、期间和之后的响应增益变化。 具体目标3是为了测试感觉反应的调制与有关任务的先验信息的类型的变化。 每个实验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耦合。 将检验三个假设：（1）如果在运动开始附近出现或如果先前已经出现其他躯体感觉刺激，则要求行为改变的感觉刺激在改变运动方面不太有效，（2）当针对目标运动的视觉反馈的增益突然改变时，感觉响应更好地被振动刺激所吸引，并且运动相关活动更紧密地与运动运动学耦合，以及（3）知道跟踪目标偏差发生在何处而不是在哪个方向上导致对被时间锁定到预测的跟踪目标偏差开始的大多数外围输入的抑制，而知道跟踪目标偏差将发生在哪个方向上而不是在何处（以及因此何时）导致对某些外围输入的抑制的逐渐增加。 潜在的中心假设是，外部感官信息在需要时被用来指导行为，当多余或竞争时被抑制。这些假设将进行测试，使用单电极和可能的多电极阵列记录细胞外活动的初级体感，顶叶（区5和7b），初级运动和运动前（PMd）皮层清醒，行为猴子训练执行手腕运动任务。 将通过平均向量分析评估活动与感觉刺激的耦合。使用多元回归分析将运动学与神经元活动相关联。这三种行为可用于中风、外伤性脑损伤、周围神经病变和运动障碍后感觉障碍的再训练。 通过了解行为过程中躯体感觉反应性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.