Mechanisms and Perceptual Consequences of Somatosensory Cortical Plasticity

描述（由申请人提供）：本提案的资金将用于培训申请人进行人类心理物理研究和能够执行复杂触觉识别任务的非人类灵长类动物的神经生理学研究。这些实验解决了与体感觉皮层可塑性有关的两个基本问题。首先，我们将通过描述在一项任务中引起的可塑性是否会改变执行其他任务的能力，来确定触觉训练后的皮层可塑性是否会改变相关的感知能力。虽然许多研究表明大脑皮层是可塑的，但这种可塑性与感知的关系尚不清楚。其次，我们将探讨注意诱导可塑性的机制。众所周知，注意刺激对于学习的发生是很重要的。先前的研究表明，非人类灵长类动物在同时刺激多个手指时，会在初级体感皮层3b区产生新的多手指表征（SI, 3b）。此外，选择性注意改变了体感觉神经元的放电速率和神经元间同步放电的程度。我们在这里测试注意是否通过同步性和假定的Hebbian机制的变化引起可塑性。为了解决这种可塑性的感知相关性的第一个问题，在目标1中，我们将确定用多指刺激训练人类时，单指和多指触觉空间感知会发生什么变化。我们假设多指触觉空间敏锐度会以牺牲单指触觉空间敏锐度为代价而增加。研究结果将有助于更好地理解学习机制。它也将有助于描述局灶性肌张力障碍的症状如何与触觉输入相关，以及如何指导康复期间的可塑性。我们还讨论了注意力是如何作用于可塑性机制的，以及在学习过程中可能控制注意力信号的区域是如何改变的。在目标2中，我们将研究注意在皮层可塑性中的作用，并测试一种驱动可塑性的潜在机制：可塑性是否与注意诱导的皮层同步有关？在目标2a中，我们将记录动物在接受相同的触觉刺激的情况下，同时参加多指触觉任务或视觉任务时，SI， 3b的细胞对。我们预测，在触觉任务中，细胞对将表现出更多的同步性，这将与更大的感受野扩张相对应。我们还预测，与参与视觉任务的动物相比，参与触觉刺激的动物会表现出更大的SI， 3b地图可塑性。在目标2b中，我们将分析动物学习触觉任务时腹外侧前额叶皮层（vLPFC）同时记录的数据。该区域与体感觉皮层相连，与多感觉注意机制和触觉工作记忆有关。我们预测vLPFC的活动将预测体感可塑性和注意同步性。因此，这个目标将测试一个精确的解释，为什么注意力是诱导/增强可塑性所必需的。这些结果将帮助我们更好地理解认知状态是如何与学习过程中发生的大脑过程相互作用的。

DESCRIPTION (provided by applicant): Funds for this proposal will be used to train the applicant to perform combined psychophysical studies of humans and neurophysiological studies of non-human primates able to perform complex tactile discrimination tasks. The experiments address two fundamental questions related to somatosensory cortical plasticity. First, we will determine if cortical plasticity following tactile training alters related perceptual abilities, by describing if plasticity induced during one task alters ability in performing other tasks. While many studies have shown that the cortex is plastic, it is unknown how this plasticity is related to perception in general. Second, we will investigate the mechanisms by which attention induces plasticity. It is well known that attending to stimuli is important for learning to occur. Previous studies have shown that non-human primates attending to simultaneous stimulation of multiple digits develop novel multi-digit representations in primary somatosensory cortex, area 3b (SI, 3b). Furthermore, it is known that selective attention changes somatosensory neurons' firing rate and the degree of synchronous firing between neurons. We test here whether attention causes plasticity via changes in synchrony and putative Hebbian mechanisms. To address the first question of the perceptual relevance of this plasticity, in Aim 1, we will determine what happens to single and multi-digit tactile spatial-perception as a result of training humans with multi-digit stimuli. We hypothesize that multi-digit tactile spatial acuity will increase at the expense of single digit tactile spatial acuity. The results will provide a better understanding of the mechanisms of learning. It will also help describe how symptoms of focal dystonia are related to tactile input, and how to direct plasticity during rehabilitation. We also address how attention acts upon mechanisms of plasticity and how regions that presumably control attentional signals are altered during learning. In aim 2 we will investigate the role of attention on cortical plasticity, and test a potential mechanism that drives plasticity: is plasticity is related to attentionally- induced cortical synchrony? In aim 2a we will record from cell pairs in SI, 3b while an animal attends to a multi-digit tactile task or a visual task while receiving the same tactile stimulation. We predict that cell pairs will exhibit more synchrony during the tactile task and this will correspond to greater receptive field expansion. We also predict that animals attending to a tactile stimulus will show greater SI, 3b map plasticity than animals attending to a visual task. In aim 2b, we will analyze data recorded simultaneously from the ventrolateral prefrontal cortex (vLPFC) while the animal learns the tactile task. This area is connected with somatosensory cortices, and is implicated in multisensory attentional mechanisms and tactile working memory. We predict that vLPFC activity will predict somatosensory plasticity and attentional synchrony. This aim will therefore test a precise explanation as to why attention is necessary to induce/enhance plasticity. Such results would help us to better understand how cognitive states interact with brain processes that occur during learning. PUBLIC HEALTH RELEVANCE: We wish to understand how cortical plasticity following training on a tactile discrimination task influences tactile perception and how attention alters primary somatosensory responses to enhance plasticity. The specific type of plasticity we will study is implicated in focal dystonia; therefore understanding these mechanisms will guide future treatments of this disorder. In addition, by knowing exactly how attention alters brain structure we can describe mechanisms of sensorimotor skill development and learning to guide education and rehabilitation.