title: Heat-evoked experimental pain induces long-term potentiation-like plasticity in human primary motor cortex.
abstract: We designed a new paired associative stimulation (PAS) protocol that combines experimental pain evoked by laser stimuli and transcranial magnetic stimulation (TMS) (Laser-PAS) to primary motor cortex (M1). We tested in healthy subjects whether Laser-PAS elicits cortical plasticity as reflected by long-term changes in motor-evoked potentials (MEPs) (after-effects). In separate experiments, we examined numerous variables including changes induced by varying the interstimulus intervals (ISIs) and Laser-PAS-induced changes in target and non-target muscle MEPs. We measured MEPs after repetitive laser or TMS (rTMS) pulses, and compared magnetic- and electric (TES)-induced MEPs. We tested MEPs after applying Laser-PAS with laser pulses ipsilaterally to M1. Finally, we studied subjects receiving an N-methyl-D-aspartate (NMDA) receptor antagonist (memantine) or placebo (α-lipoic acid). During Laser-PAS at the 50 ms ISI MEPs decreased, thereafter they increased for 60 min; other ISIs induced no after-effects. The after-effects remained restricted to the target muscle. Repetitive laser pulses and rTMS induced no after-effects. After Laser-PAS, TMS-induced MEPs increased, whereas TES-induced MEPs did not. Laser-PAS with laser pulses ipsilaterally to M1 left MEPs unchanged. Memantine, but not α-lipoic acid, abolished the after-effects. In conclusion, Laser-PAS elicits NMDA-dependent cortical plasticity and provides new insights into human pain-motor integration.
authors: IRCCS Neuromed Institute, Sapienza University of Rome, 00185 Rome, Italy.
authors: A
authors: A
authors: Suppa
authors: A
authors: A
authors: Biasiotta
authors: D
authors: D
authors: Belvisi
authors: L
authors: L
authors: Marsili
authors: S
authors: S
authors: La Cesa
authors: A
authors: A
authors: Truini
authors: G
authors: G
authors: Cruccu
authors: A
authors: A
authors: Berardelli
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006358:Hot Temperature; D006801:Humans; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D058748:Pain Perception / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate