title: Momentary reward induce changes in excitability of primary motor cortex.
abstract: OBJECTIVE
  To investigate the human primary motor cortex (M1) excitability changes induced by momentary reward.
  
  
  METHODS
  To test the changes in excitatory and inhibitory functions of M1, motor-evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and short-latency afferent inhibition (SAI) were tested in the abductor pollicis brevis (APB) muscle of non-dominant hand in 14 healthy volunteers by transcranial magnetic stimulation (TMS) during a behavioral task in which subjects were pseudorandomly received either reward target or non-target stimuli in response to a cue. To control sensorimotor and attention effects, a sensorimotor control task was done replacing the reward target with non-reward target.
  
  
  RESULTS
  The SICI was increased, and the SAI was decreased significantly during the presentation of the reward target stimuli. Those changes were not evident during non-reward target stimuli in the sensorimotor control task, indicating that this change is specific to momentary reward.
  
  
  CONCLUSIONS
  Momentary rewarding is associated with change in intracortical inhibitory circuits of M1.
  
  
  CONCLUSIONS
  TMS may be a useful probe to study the reward system in health and in many diseases in which its dysfunction is suspected.
authors: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors: Mohamed Nasreldin
authors: MN
authors: Thabit
authors: Masahiro
authors: M
authors: Nakatsuka
authors: Satoko
authors: S
authors: Koganemaru
authors: Gharib
authors: G
authors: Fawi
authors: Hidenao
authors: H
authors: Fukuyama
authors: Tatsuya
authors: T
authors: Mima
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012201:Reward; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult