title: The Effect of Cerebellar Degeneration on Human Sensori-motor Plasticity.
abstract: BACKGROUND
  Plasticity of the primary motor cortex (M1) has a critical role in motor control and learning. The cerebellum facilitates these functions using sensory feedback.
  
  
  OBJECTIVE
  We investigated how cerebellar degeneration influences the plasticity of the M1 by using PAS (paired associative stimulation) technique. PAS involves repeated pairs of electrical stimuli to the median nerve and transcranial magnetic stimulation (TMS) of the motor cortex. If the interval between peripheral and TMS stimulation is around 21-25 ms, corticospinal excitability is increased via a long term potentiation (LTP)-like effect within M1. Our aims were: (i) to explore the presence of a time-specific influence of cerebellar degeneration on human associative plasticity; (ii) to evaluate the role played by somatosensory pathway on cerebellar modulation of sensory-motor plasticity.
  
  
  METHODS
  We studied 10 patients with pure cerebellar atrophy and 10 age-matched healthy subjects. Motor-evoked-potentials amplitudes, short-afferent inhibition (SAI), motor thresholds, I/O curves, somatosensory-evoked-potential (SEP) were measured before, just after and 30 min after PAS at ISIs (interstimulus intervals) of 21.5 and 25 ms.
  
  
  RESULTS
  Cerebellar patients show a selective lack of LTP-like effect induced by PAS25 ms, but not at 21.5 ms. SAI was overall not truly modulated by PAS but clearly differed between cerebellar patients and healthy subjects for ISIs around 25 ms (+6 ms and +8 ms) (P < 0.01). SEPs showed the amplitude of P25 wave was markedly reduced in patients with a more severe clinical and radiological impairment of cerebellum.
  
  
  CONCLUSIONS
  Cerebellar patients have an altered capability of cerebellar filtering or processing of time-specific incoming sensory volleys, influencing the plasticity of M1.
authors.affiliation: Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy. Electronic address: rafdubbioso@gmail.com.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Dubbioso
authors.affiliation: Multimodal Functional Imaging Laboratory, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pellegrino
authors.affiliation: Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Antenora
authors.affiliation: Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: De Michele
authors.affiliation: Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Filla
authors.affiliation: Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy.
authors.forename: Lucio
authors.initials: L
authors.lastname: Santoro
authors.affiliation: Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy.
authors.forename: Fiore
authors.initials: F
authors.lastname: Manganelli
mesh_terms: D000328:Adult; D001284:Atrophy / Q000503:physiopathology*; D016022:Case-Control Studies; D002531:Cerebellum / Q000473:pathology* / Q000503:physiopathology*; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D007858:Learning; D017774:Long-Term Potentiation / Q000502:physiology; D008297:Male; D008475:Median Nerve / Q000502:physiology; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Cerebellar degeneration; LTP-like effect; Motor cortex plasticity; Paired associative stimulation; Somatosensory pathway