Individual differences in resting corticospinal excitability are correlated with reaction time and GABA content in motor cortex

Ian Greenhouse, Maedbh King, Sean Noah, Richard J Maddock, Richard B. Ivry

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Individuals differ in the intrinsic excitability of their corticospinal pathways and, perhaps more generally, their entire nervous system. At present, we have little understanding of the mechanisms underlying these differences and how variation in intrinsic excitability relates to behavior. Here, we examined the relationship between individual differences in intrinsic corticospinal excitability, local cortical GABA levels, and reaction time (RT) in a group of 20 healthy human adults. We measured corticospinal excitability at rest with transcranial magnetic stimulation, local concentrations of basal GABA with magnetic resonance spectroscopy, and RT with a behavioral task. All measurements were repeated in two separate sessions, and tests of reliability confirmed the presence of stable individual differences. There was a negative correlation between corticospinal excitability and RT, such that larger motor-evoked potentials (MEPs) measured at rest were associated with faster RTs. Interestingly, larger MEPs were associated with higher levels of GABA in M1, but not in three other cortical regions. Together, these results suggest that individuals with more excitable corticospinal pathways are faster to initiate planned responses and have higher levels of GABA within M1, possibly to compensate for a more excitable motor system.

Original languageEnglish (US)
Pages (from-to)2686-2696
Number of pages11
JournalJournal of Neuroscience
Volume37
Issue number10
DOIs
StatePublished - Mar 8 2017

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Motor Cortex
Individuality
gamma-Aminobutyric Acid
Reaction Time
Motor Evoked Potentials
Transcranial Magnetic Stimulation
Nervous System
Magnetic Resonance Spectroscopy

Keywords

  • GABA
  • Individual differences
  • Inhibition
  • MR spectroscopy
  • Reaction time
  • TMS

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Individual differences in resting corticospinal excitability are correlated with reaction time and GABA content in motor cortex. / Greenhouse, Ian; King, Maedbh; Noah, Sean; Maddock, Richard J; Ivry, Richard B.

In: Journal of Neuroscience, Vol. 37, No. 10, 08.03.2017, p. 2686-2696.

Research output: Contribution to journalArticle

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