title: Enhancing plasticity through repeated rTMS sessions: the benefits of a night of sleep.
abstract: OBJECTIVE
  Previous work has demonstrated that corticospinal facilitation from 20Hz repetitive transcranial magnetic stimulation (rTMS) was greater during a second rTMS session 24h after the first. We sought to determine whether such metaplasticity is dependent on a particular phase of the normal sleep-wake/circadian cycle.
  
  
  METHODS
  Twenty healthy participants received two sessions of 20Hz rTMS over the hand motor cortex (M1) spaced 12h apart, either over-day or overnight.
  
  
  RESULTS
  Baseline corticospinal excitability did not differ by group or session. The time-of-day of Session 1 did not influence the relative increase in excitability following rTMS. However, the increase in excitability from the second rTMS session was 2-fold greater in the overnight group.
  
  
  CONCLUSIONS
  When a night with sleep follows rTMS to M1, the capacity to induce subsequent plasticity in M1 is enhanced, suggesting sleep-wake and/or circadian-dependent modulation of processes of metaplasticity.
  
  
  CONCLUSIONS
  TMS treatment of neuropsychiatric disorders entails repeated sessions of rTMS. Our findings suggest that the timing of sessions relative to the sleep-wake/circadian cycle may be a critical factor in the cumulative effect of treatment. Future studies using this paradigm may provide mechanistic insights into human metaplasticity, leading to refined strategies to enhance non-invasive stimulation therapies.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA. dcohen2@bidmc.harvard.edu
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Cohen
authors.forename: Catarina
authors.initials: C
authors.lastname: Freitas
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Tormos
authors.forename: Lindsay
authors.initials: L
authors.lastname: Oberman
authors.forename: Mark
authors.initials: M
authors.lastname: Eldaief
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult