Department of Psychology, Vanderbilt University, Nashville, TN 37240.
Proc Natl Acad Sci U S A. 2023 Mar 14;120(11):e2222076120. doi: 10.1073/pnas.2222076120. Epub 2023 Mar 6.
Neurons in the early stages of processing sensory information suffer transneuronal atrophy when deprived of their activating inputs. For over 40 y, members of our laboratory have studied the reorganization of the somatosensory cortex during and after recovering from different types of sensory loss. Here, we took advantage of the preserved histological material from these studies of the cortical effects of sensory loss to evaluate the histological consequences in the cuneate nucleus of the lower brainstem and the adjoining spinal cord. The neurons in the cuneate nucleus are activated by touch on the hand and arm, and relay this activation to the contralateral thalamus, and from the thalamus to the primary somatosensory cortex. Neurons deprived of activating inputs tend to shrink and sometimes die. We considered the effects of differences in species, type and extent of sensory loss, recovery time after injury, and age at the time of injury on the histology of the cuneate nucleus. The results indicate that all injuries that deprived part or all of the cuneate nucleus of sensory activation result in some atrophy of neurons as reflected by a decrease in nucleus size. The extent of the atrophy is greater with greater sensory loss and with longer recovery times. Based on supporting research, atrophy appears to involve a reduction in neuron size and neuropil, with little or no neuron loss. Thus, the potential exists for restoring the hand to cortex pathway with brain-machine interfaces, for bionic prosthetics, or biologically with hand replacement surgery.
在处理感觉信息的早期阶段，神经元在失去激活输入时会遭受跨神经元萎缩。我们实验室的成员在过去 40 多年来一直在研究不同类型的感觉丧失过程中和之后，躯体感觉皮层的重组。在这里，我们利用这些关于感觉丧失对皮层影响的研究中保留的组织学材料，评估了低位脑干楔状核和相邻脊髓中的组织学后果。楔状核中的神经元在手和手臂的触摸中被激活，并将这种激活传递到对侧丘脑，然后从丘脑传递到初级躯体感觉皮层。失去激活输入的神经元往往会收缩，有时甚至死亡。我们考虑了物种差异、感觉丧失的类型和程度、受伤后恢复时间以及受伤时的年龄对楔状核组织学的影响。结果表明，所有导致楔状核部分或全部丧失感觉激活的损伤都会导致神经元萎缩，表现为核体积减小。萎缩的程度随着感觉丧失的增加和恢复时间的延长而增加。基于支持性研究，萎缩似乎涉及神经元和神经胶质的减少，而神经元丢失很少或没有。因此，有可能通过脑机接口、仿生假肢或生物性手部置换手术来恢复手部到皮层的通路。
