Numbers within our hands: modulation of corticospinal excitability of hand muscles during numerical judgment

J Cogn Neurosci. 2007 Apr;19(4):684-93. doi: 10.1162/jocn.2007.19.4.684.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Evoked Potentials, Motor / physiology*
  • Female
  • Fingers / physiology*
  • Hand / physiology
  • Humans
  • Judgment / physiology*
  • Male
  • Mathematics*
  • Movement / physiology*
  • Muscle, Skeletal / physiology
  • Pyramidal Tracts / physiology*
  • Reference Values
  • Transcranial Magnetic Stimulation