Ni Zheyi, Neifert Connor, Rosete Arturo, Albeely Abdalla M, Yang Yu, Pratelli Marta, Brecht Michael, Clemens Ann M
Neural Systems & Behavior, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA; Department of Neurobiology, Affiliated Mental Health Center & Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China.
Neural Systems & Behavior, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA; Department of Bioengineering, University of Texas at Dallas, 800 W Campbell Road, Richardson, TX 75080, USA.
Curr Biol. 2024 Dec 2;34(23):5595-5601.e2. doi: 10.1016/j.cub.2024.10.016. Epub 2024 Nov 4.
Juvenile rodents and other altricial mammals react with calming, immobility, and postural modifications to parental pickup, a set of behaviors referred to as the transport response. Here, we investigate sensory mechanisms underlying the rat transport response. Grasping rat pups in anterior neck positions evokes strong immobility and folding up of feet, whereas more posterior grasping has lesser effects on immobility and foot position. Transport responses are enhanced by slow (1 Hz), and even more so by fast (4 Hz), gentle shaking and translation, features consistent with parental transport. With lateral grasping, the forepaw below the grasping position points downward and the forepaw lateral to the grasping position points upward and medially. Such forepaw adjustments put the pup's center of gravity below the grasping point, optimizing pup transportability. Tactile stimuli on the back, belly, tail, whisker, dorsal forepaws, and dorsal hind-paws do not significantly affect behavior of anterior-neck-held pups. Instead, ground contact, or paw stimulation consistent with ground contact, disrupts transport responses. We identify afferents mediating transport response by examining membrane labeling with FM 1-43 following anterior neck grasping. We observe a dense innervation of the anterior-neck-skin region (∼30 terminals/mm). We find an age-related decrease of cytochrome oxidase reactivity in the rat somatosensory cortical neck representation, a possible correlate to developmental decrease in pup transport response. We conclude that anterior neck grasping and loss of ground contact trigger calming and postural adjustments for parental transport in rat pups, responses putatively driven from the densely innervated anterior neck skin.
幼年啮齿动物和其他晚成哺乳动物在被父母抱起时会表现出平静、不动以及姿势改变，这一系列行为被称为运输反应。在此，我们研究大鼠运输反应背后的感觉机制。从前颈部抓住幼鼠会引发强烈的不动和足部蜷缩，而后部抓握对不动和足部位置的影响较小。缓慢（1赫兹）的摇晃以及更快速（4赫兹）的轻柔摇晃和平移会增强运输反应，这些特征与父母的运输方式一致。在侧向抓握时，抓握位置下方的前爪向下指，抓握位置外侧的前爪向上并向内指。这种前爪的调整使幼崽的重心低于抓握点，优化了幼崽的可运输性。背部、腹部、尾巴、胡须、背侧前爪和背侧后爪上的触觉刺激不会显著影响前颈部被抓住的幼崽的行为。相反，地面接触或与地面接触一致的爪子刺激会破坏运输反应。我们通过在前颈部抓握后用FM 1-43检查膜标记来识别介导运输反应的传入神经。我们观察到前颈部皮肤区域有密集的神经支配（约30个终末/毫米）。我们发现大鼠体感皮层颈部表征中细胞色素氧化酶反应性随年龄下降，这可能与幼崽运输反应的发育性下降有关。我们得出结论，前颈部抓握和失去地面接触会触发幼鼠对父母运输的平静和姿势调整，这些反应可能是由密集神经支配的前颈部皮肤驱动的。
