title: A local signature of LTP-like plasticity induced by repetitive paired associative stimulation.
abstract: Repetitive paired associative stimulation (rPAS) repeatedly pairs electrical nerve stimulation (ENS) with transcranial magnetic stimulation (TMS) of the contralateral motor hand area (M1) at 5 Hz frequency. So far, there are only few studies concerning the effects of PAS on the modulation of EEG power. Hence, aim of the present study was to investigate rPAS long term after-effects on cortical excitability looking at EEG power spectra. In four experimental sessions, separated by 2 weeks interval, 12 awake subjects received rPAS of the right median nerve and left M1 at a fixed interval (ISI) of 25 ms (real condition), 5 Hz-TMS on left M1, 5 Hz-ENS, of the right median nerve, and rPAS with changing ISI (sham condition). We measured peak-to-peak MEP amplitude, evoked from the target muscle (right abductor pollicis brevis muscle) at rest and the absolute power (POW) in four frequency bands: α (8-12 Hz), β (13-30), θ (4-7) and δ (1-3), under rest conditions. All these parameters were evaluated in three detection blocks: baseline, immediately after and after 30' from the end of the conditioning protocol. Real rPAS induced a long-lasting homotopic cortical excitability modulation, as indexed by MEP amplitude increase, that was paralleled by a long-lasting reduction of α/β-POW and by a widespread θ-δ-POW modulation. rPAS applied over the sensory-motor cortex induced an LTP-like plasticity, as indexed by a robust reduction in the α/β POW positively correlated with the MEP amplitude increase. rPAS25ms may be a useful tool for motor neurorehabilitation promoting a sensory-motor coupling within β oscillations.
authors.affiliation: IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy, g.naro11@alice.it.
authors.forename: Antonino
authors.initials: A
authors.lastname: Naro
authors.forename: Margherita
authors.initials: M
authors.lastname: Russo
authors.forename: Mohamed
authors.initials: M
authors.lastname: AbdelKader
authors.forename: Paolo
authors.initials: P
authors.lastname: Manganotti
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Genovesi
authors.forename: Marco
authors.initials: M
authors.lastname: Marino
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Rizzo
authors.forename: Rocco Salvatore
authors.initials: RS
authors.lastname: Calabrò
authors.forename: Paolo
authors.initials: P
authors.lastname: Girlanda
authors.forename: Angelo
authors.initials: A
authors.lastname: Quartarone
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods*; D004569:Electroencephalography; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*