Adaptive sensory coding in rat somatosensory cortex

描述(由申请人提供)：长期目标是表征早期躯体感觉皮层感觉编码策略中依赖学习的变化。最终，我们的目标是在现象学和机械论层面上描述这种变化。目前的研究重点是确定这种可塑性是否存在。具体地说，我们将测试这样一种假设，即学习依赖胡须的感觉辨别任务可以提高大鼠第一和第二躯体感觉皮质(SI和SLL)神经元集合中感觉代码的准确性。我们之前已经量化了老鼠使用胡须在行为上区分狭缝和宽缝的能力。我们将首先创建这个任务的一个版本，在这个任务中，RAT将区分两个光圈宽度类别(“窄”和“宽”)，每个类别都包含两个宽度。我们将设计刺激类别，使类别内宽度之间的距离等于类别间宽度之间的最小距离。在设计任务后，我们将在SI和SLL植入多电极阵列，并在大鼠学习任务的同时记录神经元群体。我们预测，SI和SLL对类间宽度(即，行为上受到歧视的宽度)的辨别能力将好于相隔相同物理距离的类内宽度(即，老鼠不会在行为上加以区分的宽度)。我们将用基于神经反应估计孔径宽度的分类器的正确率来量化辨别力。研究皮质可塑性的机制有相当大的潜在临床价值。如果早期感觉皮层通过行为训练调整其编码策略，这将为周围神经损伤患者神经假体的发展带来巨大希望，为那些有轻微感觉障碍(例如，阅读障碍)的患者提供重新训练的行为范例，并建议潜在的药物操作以最大限度地发挥此类治疗的有效性。由于大鼠学习胡须依赖的行为任务很容易，而且胡须刺激的皮质表现相对简单，大鼠胡须系统是研究这种现象的理想模型系统。

DESCRIPTION (provided by applicant): The long-term goal is to characterize learning-dependent changes in sensory coding strategies in early somatosensory cortices. Ultimately, we aim to characterize such changes both at a phenomenological and mechanistic level. The present research focuses on determining whether such plasticity exists. Specifically, we will test the hypothesis that learning a whisker-dependent sensory discrimination task increases the accuracy of the sensory code in neuronal ensembles in the first and second somatosensory cortices (SI and Sll) of the rat. We have previously quantified the rat's ability to behaviorally discriminate between a narrow and wide aperture using its whiskers. We will first create a version of this task in which the rats will discriminate between two aperture width categories ('narrow' and 'wide'), each of which contains two widths. We will design the stimulus categories so that the distance between widths within a category is identical to the minimum distance between widths across categories. After designing the task, we will implant multielectrode arrays in SI and Sll and record from neuronal populations while rats learn the task. We predict that SI and Sll will discriminate the between-class widths (i.e., those behaviorally discriminated) better than within-class widths (i.e., those which the rat does not behaviorally discriminate) that are separated by the same physical distance. We will quantify discrimination with percent correct of a classifier that estimates aperture width based on the neural response. There are considerable potential clinical rewards for characterizing the mechanisms of cortical plasticity. If early sensory cortices adapt their coding strategies via behavioral training, this would offer great hope for the development of neuroprosthetics in patients with peripheral nerve damage, suggest behavioral paradigms for retraining those with minor sensory impairments (e.g., dyslexics), and suggest potential pharmacological manipulations to maximize the effectiveness of such treatments. Because of the ease with which rats learn whisker-dependent behavioral tasks, and the relative simplicity of the cortical representation of whisker stimuli, the rat whisker system is an ideal model system for examining such phenomena.