Sensorimotor Experience Influences Recovery of Forelimb Abilities but Not Tissue Loss after Focal Cortical Compression in Adult Rats

Sensorimotor activity has been shown to play a key role in functional outcome after extensive brain damage. This study was aimed at assessing the influence of sensorimotor experience through subject-environment interactions on the time course of both lesion and gliosis volumes as well as on the recovery of forelimb sensorimotor abilities following focal cortical injury. The lesion consisted of a cortical compression targeting the forepaw representational area within the primary somatosensory cortex of adult rats. After the cortical lesion, rats were randomly subjected to various postlesion conditions: unilateral C5–C6 dorsal root transection depriving the contralateral cortex from forepaw somatosensory inputs, standard housing or an enriched environment promoting sensorimotor experience and social interactions. Behavioral tests were used to assess forelimb placement during locomotion, forelimb-use asymmetry, and forepaw tactile sensitivity. For each group, the time course of tissue loss was described and the gliosis volume over the first postoperative month was evaluated using an unbiased stereological method. Consistent with previous studies, recovery of behavioral abilities was found to depend on post-injury experience. Indeed, increased sensorimotor activity initiated early in an enriched environment induced a rapid and more complete behavioral recovery compared with standard housing. In contrast, severe deprivation of peripheral sensory inputs led to a delayed and only partial sensorimotor recovery. The dorsal rhizotomy was found to increase the perilesional gliosis in comparison to standard or enriched environments. These findings provide further evidence that early sensory experience has a beneficial influence on the onset and time course of functional recovery after focal brain injury.

已有研究表明，感觉运动活动在广泛性脑损伤后的功能预后中发挥关键作用。本研究旨在探讨通过主体-环境交互产生的感觉运动经验，对局灶性皮层损伤后病灶体积、胶质增生体积的时间进程，以及前肢感觉运动功能恢复的影响。本研究采用的皮层损伤模型为：对成年大鼠初级躯体感觉皮层内的前肢代表区施加皮层压迫损伤。皮层损伤造模后，大鼠被随机分配至三种术后干预条件：单侧C5-C6背根切断术（以剥夺对侧皮层的前肢躯体感觉输入）、标准饲养环境，或可促进感觉运动经验与社交互动的丰富环境饲养。通过行为学测试评估大鼠运动过程中的前肢放置能力、前肢使用不对称性，以及前肢触觉敏感性。对各组大鼠的组织丢失时间进程进行了描述，并采用无偏体视学方法评估了术后首个月份内的胶质增生体积。与既往研究结果一致，本研究发现行为能力的恢复依赖于损伤后的干预经验。具体而言，相较于标准饲养组，早期在丰富环境中开展的强化感觉运动活动可促使行为能力快速且更完全地恢复。与之相反，外周感觉输入的严重剥夺会导致感觉运动功能恢复延迟，且仅能实现部分恢复。研究发现，相较于标准饲养或丰富环境饲养组，背根切断术会增加病灶周围的胶质增生体积。本研究结果进一步证实，早期感觉经验对局灶性脑损伤后功能恢复的启动及时间进程具有积极影响。