Numbers within our hands: modulation of corticospinal excitability of hand muscles during numerical judgment.
Developmental and cross-cultural studies show that finger counting represents one of the basic number learning strategies. However, despite the ubiquity of such an embodied strategy, the issue of whether there is a neural link between numbers and fingers in adult, literate individuals remains debated. Here, we used transcranial magnetic stimulation to study changes of excitability of hand muscles of individuals performing a visual parity judgment task, a task not requiring counting, on Arabic numerals from 1 to 9. Although no modulation was observed for the left hand muscles, an increase in amplitude of motor-evoked potentials was found for the right hand muscles. This increase was specific for smaller numbers (1 to 4) as compared to larger numbers (6 to 9). These findings indicate a close relationship between hand/finger and numerical representations.
Sato
Marc
M
Università degli studi di Parma, Italy. marc.sato@mail.mcgill.ca
Cattaneo
Luigi
L
Rizzolatti
Giacomo
G
Gallese
Vittorio
V
D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology*; D006225:Hand / Q000502:physiology; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008297:Male; D008433:Mathematics; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D011712:Pyramidal Tracts / Q000502:physiology*; D012016:Reference Values; D050781:Transcranial Magnetic Stimulation