Recovery of the CTM Reflex in Spinal-Injured Guinea Pigs After Exposure to Applied Extracellular Voltages
Implantable stimulator systems similar to those used in anatomical studies were used in tests designed to see if applied voltages could produce behavioral recovery of the CTM reflex. Since the CTM receptive fields are bilaterally organized (refer to Fig. 10), a complete transection of the right side of the spinal cord eliminated the CTM reflex on the right side of the animal below the level of the lesion. This technique was employed in several studies where the intact left side of the spinal cord was associated with a functioning left CTM receptive field. The receptive fields above and ipsilateral to the lesion were also unaffected by the hemisection. This allowed the animal to serve as its own control (Borgens et al. 1987, 1990). Please recall that severing the ascending CTM nerve tract eliminates the reflex for the life of the animal. One hundred percent of untreated control animals do not spontaneously recover this reflex for observation times over 1 year (see Borgens et al. 1993a).