DELAYED APPLICATION OF DIRECT-CURRENT ELECTRIC-FIELDS IN EXPERIMENTALSPINAL-CORD INJURIES

The cutaneus trunci muscle (CTM) reflex of guinea pigs depends on an a scending afferent pathway within the ventrolateral funiculus of the th oracic spinal cord. The expression of this reflex is a phasic contract ion of back skin in response to tactile stimulation, which is permanen tly eliminated by transection of the ventrolateral funiculus. It was s hown previously that when a polarized (rostrally negative), weak (300- 400 muV/mm) DC electric field is placed across a lateral hemisection o f the spinal cord in adult guinea pigs at the time of injury, approxim ately 13 % recover the reflex, while sham-treated animals remain uncha nged. In this study, a similar approach was used, except that three mo nths were allowed to pass between the time of hemisection and experime ntal treatment. No recovery of the CTM reflex was observed in 13 anima ls with rostrally negative fields, 8 of which were followed for at lea st 9 months, 5 for 3 months; or in 11 animals with caudally negative a pplied fields, 8 of which were followed for 9 months and 3 for 3 month s.