Meeting Abstract
Locomotor training has proven integral to recovery following nerve cord lesions in humans and animals alike. While we know that locomotor training aids these individuals, we do not understand the mechanism behind this recovery at the cellular level. Through the use of an invertebrate model, the leech Hirudo verbana, we are taking a closer look at this process of recovery. Leeches have two primary locomotor behaviors—swimming and crawling. Following nerve cord transections leeches lose the ability to crawl and instead swim seemingly ceaselessly. However, over time, they regain the ability to crawl and to suppress swimming behavior despite that the nerve cord does not reattach. Can physical therapy help leeches to regain normal crawling behavior earlier? We have developed several physical therapy regimes to examine this question. We have found that crawl quantity and crawl quality are separable features. Quantity can be increased to reach pre-lesion levels through a physical therapy regimen which prohibits swimming during recovery. However, this therapy does not result in coordinated (quality) crawls. Instead crawl quality is impacted by placing individuals in a device which approximates their position during crawling. This device does not aid the leeches in regaining quantity of crawls. Furthermore, the device is ineffective if the leech is passively moved through the device instead of actively. This suggests that leeches must actively be involved in their recovery following lesion, and that crawl quantity and quality are controlled through different neural mechanisms.
