Spinal cord neuron inputs to the cuneate nucleus that partially survive dorsal column lesions: A pathway that could contribute to recovery after spinal cord injury
Year: 2015
Type: article
Abstract: Dorsal column lesions at a high cervical level deprive the cuneate nucleus and much of the somatosensory system of its major cutaneous inputs. Over weeks of recovery, much of the hand representations in the contralateral cortex are reactivated. One possibility for such cortical reactivation by hand afferents is that preserved second-order spinal cord neurons reach the cuneate nucleus through pathways that circumvent the dorsal column lesions, contributing to cortical reactivation in an increasingly effective manner over time. To evaluate this possibility, we first injected anatomical tracers into the cuneate nucleus and plotted the distributions of labeled spinal cord neurons and fibers in control monkeys. Large numbers of neurons in the dorsal horn of the cervical spinal cord were labeled, especially ipsilaterally in lamina IV. Labeled fibers were distributed in the cuneate fasciculus and lateral funiculus. In three other squirrel monkeys, unilateral dorsal column lesions were placed at the cervical segment 4 level and tracers were injected into the ipsilateral cuneate nucleus. Two weeks later, a largely unresponsive hand representation in contralateral somatosensory cortex confirmed the effectiveness of the dorsal column lesion. However, tracer injections in the cuneate nucleus labeled only about 5% of the normal number of dorsal horn neurons, mainly in lamina IV, below the level of lesions. Our results revealed a small second-order pathway to the cuneate nucleus that survives high cervical dorsal column lesions by traveling in the lateral funiculus. This could be important for cortical reactivation by hand afferents, and recovery of hand use.
DOI: 10.1002/cne.23783
Institution: Vanderbilt University
Language: English
Topic: Spinal Cord Injury Research
Subfield: Pathology and Forensic Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
Awards: G206835787, G2356599214, Functional Organization of the Somatosensory System, Organization of the parietal-frontal network that mediates grasping in monkeys, Eunice Kennedy Shriver Intellectual and Developmental Disabilities Research Center at Vanderbilt University, Cortical reorganization and behavioral recovery after sensory loss, Organization of the parietal-frontal network that mediates grasping in monkeys
OpenAlex ID: W1999377639