Sumser Anton, Isaías-Camacho Emilio Ulises, Mease Rebecca Audrey, Groh Alexander
Division of Neuroscience, Faculty of Biology, LMU Munich, Martinsried, Germany.
Medical Biophysics, Institute for Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany.
PLoS Biol. 2025 Apr 8;23(4):e3003108. doi: 10.1371/journal.pbio.3003108. eCollection 2025 Apr.
Active and passive sensing strategies are integral to an animal's behavioral repertoire. Nevertheless, there is a lack of information regarding the neuronal circuitry that underpins these strategies, particularly at the thalamus level. We evaluated how active versus passive whisker deflections are represented in single neurons of the ventral posteromedial thalamus (VPM) and the posterior medial thalamus (POm) in awake mice. These are the first- and higher-order thalamic nuclei of the whisker system, respectively. VPM neurons robustly responded to both active and passive whisker deflections, while POm neurons showed a preference for passive deflections and responded poorly to active touches. This response disparity could not be explained by stimulus kinematics and only in part by the animal's voluntary whisking state. In contrast, cortical activity significantly influenced POm's responses to passive touch. Inhibition of the barrel cortex strongly attenuated whisker responses in POm and simultaneously increased the whisking phase coding. This suggests that POm receives touch information from the cortex which strongly adapts and is gated by rare events. Together, these findings suggest two thalamic relay streams, where VPM robustly relays both active and passive deflection, while POm's sensitivity requires top-down cortical involvement to signal salient events such as unexpected deflections, originating in the environment.
主动和被动感知策略是动物行为库的组成部分。然而，关于支撑这些策略的神经回路的信息却很缺乏，尤其是在丘脑层面。我们评估了清醒小鼠腹后内侧丘脑（VPM）和丘脑后内侧核（POm）的单个神经元中主动与被动触须偏转是如何被表征的。这些分别是触须系统的一级和高级丘脑核团。VPM神经元对主动和被动触须偏转都有强烈反应，而POm神经元则表现出对被动偏转的偏好，对主动触摸反应较差。这种反应差异无法用刺激运动学来解释，且仅部分可由动物的自主触须状态来解释。相反，皮层活动显著影响了POm对被动触摸的反应。抑制桶状皮层会强烈减弱POm中的触须反应，并同时增加触须相位编码。这表明POm从皮层接收触摸信息，该信息会强烈适应并由罕见事件进行门控。总之，这些发现表明存在两条丘脑中继流，其中VPM强烈中继主动和被动偏转，而POm的敏感性需要自上而下的皮层参与来信号化源自环境的突出事件，如意外偏转。
