Electrical Spinal Imaging: A noninvasive, high-resolution approach that enables electrophysiological mapping of the human spinal cord
Fig 7
Neural generators of the recorded responses.
Schematic representations of the putative spinal mechanisms generating the electrocortical responses recorded with ESI. The sP9 appears as a traveling wave (see also the delay map in Fig 4) as it reflects the current sink entering the cord through the dorsal roots and traveling rostrally along the dorsal column tracts. In contrast, the stationary sN13 reflects the segmental postsynaptic activity occurring in the deep dorsal horn following the first arrival of somatosensory input. Finally, the late sP22 is not directly consequent to a local, segmental effect of the incoming somatosensory input, but instead reflects stimulus-triggered activation of a long-loop circuit involving supraspinal structures that, in turn, project top-down to the spinal cord. For this reason, the sP22 encompasses spinal segments rostral and caudal to those where the sP9 and sP13 are recorded (Fig 3 and S1, S2 and S3 Videos).