Somatosensory stimuli guide and shape behavior, from immediate protective reflexes to longer-term learning and high-order processes related to pain and touch. However, somatosensory inputs are challenging to control in awake mammals due to the diversity and nature of contact stimuli. Application of cutaneous stimuli is currently limited to relatively imprecise methods as well as subjective behavioral measures. The strategy we present here overcomes these difficulties by achieving spatiotemporally precise, remote and dynamic optogenetic stimulation of skin by projecting light to a small defined area in freely-behaving mice. We mapped behavioral responses to specific nociceptive inputs and revealed a sparse code for stimulus intensity: using the first action potential, the number of activated nociceptors governs the timing and magnitude of rapid protective pain-related behavior. The strategy can be used to define specific behavioral repertoires, examine the timing and nature of reflexes, and dissect sensory, motor, cognitive and motivational processes guiding behavior.

中文翻译：

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哺乳动物体感输入的扫描光遗传学控制，以映射特定于输入的行为输出

从立即的保护性反射到长期学习以及与疼痛和触觉有关的高级过程，体感刺激指导和塑造行为。然而，由于接触刺激的多样性和性质，在觉醒的哺乳动物中体感输入难以控制。目前，皮肤刺激的应用仅限于相对不精确的方法以及主观行为措施。我们在这里提出的策略通过将光投射到行为自由的小鼠的较小限定区域来实现时空精确，远程和动态的皮肤光遗传刺激，从而克服了这些困难。我们将行为反应映射到特定的伤害感受输入，并揭示了刺激强度的稀疏代码：使用第一个动作电位，激活的伤害感受器的数量决定着快速的保护性疼痛相关行为的时间和大小。该策略可用于定义特定的行为方式，检查反射的时机和性质，并剖析指导行为的感觉，运动，认知和动机过程。