Abstract: Electrical stimulation of the central and peripheral nervous systems improves neuronal connectivity. Here we described a new configuration of electrical stimulation as it was tested in anesthetized control and spinal cord injury (SCI) mice. Constant voltage output was delivered through two electrodes. While the negative voltage output (ranging from -1.8 to -2.6V) was delivered to the muscle, the positive output (ranging from +2.4 to +3.2V) was delivered to the primary motor cortex (M1). The configuration was named dipolar cortico-muscular stimulation (dCMS) and consisted of 100 pulses (1 ms pulse duration, 1 Hz frequency). In SCI animals, after dCMS, muscle contraction improved remarkably at the contralateral (456%) and ipsilateral (457%) gastrocnemius muscles. The improvement persisted for the duration of the experiment (60 min). The enhancement of the muscle force was accompanied by the reduction of M1 maximal threshold and the potentiation of spinal motoneuronal evoked responses at the contralateral (313%) and ipsilateral (292%) sides of the spinal cord. Moreover, spontaneous activity recorded from single spinal motoneurons was substantially increased contralaterally (121%) and ipsilaterally (54%). Interestingly, spinal motoneuronal responses and muscle twitches evoked by the test stimulation of non-treated M1 (received no dCMS) were significantly enhanced as well. Similar results obtained from normal animals albeit the changes were relatively smaller. These findings demonstrated that dCMS could improve functionality of motor pathway and dramatically attenuate the effects of spinal cord injury.

zaghloul Ahmed¹,

¹Department of Physical Therapy and CSI/IBR Center for Developmental Neuroscience – The College of Staten Island/CUNY

Keywords: spinal cord injury , electrical stimulation , functional recovery