BACKGROUND: Theories of embodied language suggest that the motor system is differentially called into action when processing motor-related versus abstract content words or sentences.It has been recently shown that processing negative polarity action-related sentences modulates neural activity of premotor and motor cortices.METHODS AND FINDINGS: We sought to determine whether reading negative polarity sentences brought sony c about differential modulation of cortico-spinal motor excitability depending on processing hand-action related or abstract sentences.
Facilitatory paired-pulses Transcranial Magnetic Stimulation (pp-TMS) was applied to the primary motor representation of the right-hand and the recorded amplitude of induced motor-evoked potentials (MEP) was used to index M1 activity during passive reading of either hand-action related or abstract content sentences presented in both negative and affirmative polarity.Results showed that the cortico-spinal excitability was affected by sentence polarity only in the hand-action related condition.Indeed, in keeping with previous TMS studies, reading positive polarity, hand action-related sentences suppressed cortico-spinal reactivity.
This effect was absent when reading hand action-related negative polarity sentences.Moreover, no modulation of cortico-spinal reactivity was associated with either negative or positive polarity abstract sentences.CONCLUSIONS: Our results indicate that grammatical cues prompting motor negation reduce the cortico-spinal suppression associated with affirmative action sharps honda sentences reading and thus suggest that motor simulative processes underlying the embodiment may involve even syntactic features of language.