title: Val66Met BDNF gene polymorphism influences human motor cortex plasticity in acute stroke.
abstract: BACKGROUND
  BDNF gene polymorphism impacts human motor cortex function and plasticity.
  
  
  OBJECTIVE
  Using transcranial magnetic stimulation (TMS), we investigated whether BDNF polymorphism influences cortical plastic changes in acute stroke.
  
  
  METHODS
  Twenty patients were recruited within 10 days of their first-ever ischemic stroke and genotyped for BDNF polymorphism. Blinded to the latter, we evaluated the excitability of the affected and unaffected hemisphere by measuring resting and active motor threshold and motor-evoked potential amplitude under baseline conditions and after intermittent theta burst stimulation, a protocol of repetitive TMS inducing LTP-like activity. We also computed laterality indexes to assess inter-hemispheric excitability imbalance.
  
  
  RESULTS
  Demographics, threshold and amplitude of motor-evoked potentials did not differ between those with (8 patients) and without polymorphism. Excitability of the unaffected hemisphere was significantly higher than the excitability of the affected hemisphere as probed by each measure. This imbalance was exaggerated in those without polymorphism; laterality indexes of rest motor thresholds were 0.016 ± 0.050 and 0.139 ± 0.028 for patients with and without polymorphism [t = 2.270, P = 0.036]. Exaggerated hemispheric imbalance also persisted after intermittent theta burst stimulation, which failed to induce any difference between groups.
  
  
  CONCLUSIONS
  Our results suggest that inter-hemispheric imbalance with greater excitability over unaffected hemisphere, is several times stronger in stroke patients without, as opposed to with, polymorphism.
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy. Electronic address: v.dilazzaro@unicampus.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Di Lazzaro
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pellegrino
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Pino
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Marzia
authors.initials: M
authors.lastname: Corbetto
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Ranieri
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Brunelli
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Paolucci
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Bucossi
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Ventriglia
authors.affiliation: Nuffield Department of Clinical Neurosciences, University of Oxford, West Wing, John Radcliffe Hospital, OX3 9DU Oxford, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
authors.affiliation: Institute of Neurology, Università Campus Bio-Medico, Via Alvaro del Portillo 200, 00128 Rome, Italy; Fondazione Alberto Sordi, Research Institute for Ageing, Via Alvaro del Portillo 5, 00128 Rome, Italy.
authors.forename: Fioravante
authors.initials: F
authors.lastname: Capone
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity / Q000235:genetics* / Q000502:physiology; D020641:Polymorphism, Single Nucleotide / Q000502:physiology*; D020521:Stroke / Q000235:genetics* / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
chemical_list: D019208:Brain-Derived Neurotrophic Factor
keywords: Acute cerebral infarction; BDNF; Neurophysiology; Stroke; Transcranial magnetic stimulation