Nociceptive stimulation suppresses spinal beta oscillations in awake human epidural recordings

IntroductionNociceptive processing in the human spinal cord remains difficult to study directly, and its oscillatory dynamics are poorly understood. Oscillatory activity in the beta band (13-35 Hz) is of particular interest, as beta rhythms are widely associated with sensorimotor network state and transient desynchronisation following salient input. ObjectivesIdentify the effects of nociceptive laser thermal stimuli on beta-band oscillatory activity in epidural spinal field potentials. MethodsWe recorded epidural spinal field potentials during noxious thermal laser stimulation of the unaffected foot using externalised thoracic spinal cord stimulation electrodes in two subjects with neuropathic pain (persistent spinal pain syndrome type 2). ResultsTime-frequency analysis combined with cluster-based permutation testing revealed reproducible suppression of spinal beta oscillations (13-35 Hz) following nociceptive stimulation. Beta suppression was spatially organised along contiguous rostro-caudal bipolar channels and most prominent within the first 0-200 ms after stimulation. Both low- (13-20 Hz) and high-beta (20-35 Hz) sub-bands contributed to early effects, with low-beta suppression predominating rostrally and while high-beta suppression was more ubiquitous. Inter-trial coherence increases were modest and not consistently aligned with early suppression, suggesting induced desynchronisation rather than a dominant phase-reset response. ConclusionNociceptive input produces early, spatially organised modulation of spinal beta oscillation dynamics in awake subjects.