Shifts in connectivity during procedural learning after motor cortex stimulation: A combined transcranial magnetic stimulation/functional magnetic resonance imaging study. (January 2016)

• Record Type: Journal Article
• Authors: Steel, Adam; Song, Sunbin; Bageac, Devin; Knutson, Kristine M.; Keisler, Aysha; Saad, Ziad S.; Gotts, Stephen J.; Wassermann, Eric M.; Wilkinson, Leonora
• Is Part Of: Cortex. Volume 74(2016)
• Page Start: 134
• Page End: 148
• Publication Date: 2016-01
• Subjects: Continuous theta burst stimulation -- Functional connectivity -- Primary motor cortex -- Probabilistic sequence learning -- Procedural learning; AMT active motor threshold -- BOLD Blood oxygen level-dependent -- cTBS continuous theta burst stimulation -- cTBS 300 a 20 sec uninterrupted train of theta burst of 300 pulses -- cTBS 600 a 40 sec uninterrupted train of theta burst of 600 pulses -- dACC dorsal anterior cingulate -- EPI echo planar imaging sequence -- FDI first dorsal interosseous muscle -- fMRI functional magnetic resonance imaging -- FOV field of view -- GCOR global correlation -- imp improbable -- IFG inferior frontal gyrus -- M1 primary motor area -- mCC middle cingulate gyrus -- MEP motor evoked potential -- MPRAGE magnetization-prepared rapid gradient echo -- MRI magnetic resonance imaging -- MT middle temporal area -- PDP process dissociation procedure -- PMd dorsal premotor cortex -- prob probable -- pSRTT probabilistic serial reaction time task -- R Random block -- ROIs regions of interest -- RT reaction time -- S Sequence block -- SFG superior frontal gyrus -- SOC second order conditional -- SMA supplementary motor area -- SRTT serial reaction time task -- TE echo time -- TMS transcranial magnetic stimulation -- TR repetition time; Neuropsychology -- Periodicals; Nervous system -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Behavior -- Periodicals; Neurology -- Periodicals; 612.825
• DOI: 10.1016/j.cortex.2015.10.004
• Languages: English
• ISSNs: 0010-9452

Abstract

Abstract: Inhibitory transcranial magnetic stimulation (TMS), of which continuous theta burst stimulation (cTBS) is a common form, has been used to inhibit cortical areas during investigations of their function. cTBS applied to the primary motor area (M1) depresses motor output excitability via a local effect and impairs procedural motor learning. This could be due to an effect on M1 itself and/or to changes in its connectivity with other nodes in the learning network. To investigate this issue, we used functional magnetic resonance imaging to measure changes in brain activation and connectivity during implicit procedural learning after real and sham cTBS of M1. Compared to sham, real cTBS impaired motor sequence learning, but caused no local or distant changes in brain activation. Rather, it reduced functional connectivity between motor (M1, dorsal premotor & supplementary motor areas) and visual (superior & inferior occipital gyri) areas. It also increased connectivity between frontal associative (superior & inferior frontal gyri), cingulate (dorsal & middle cingulate), and temporal areas. This potentially compensatory shift in coupling, from a motor-based learning network to an associative learning network accounts for the behavioral effects of cTBS of M1. The findings suggest that the inhibitory TMS affects behavior via relatively subtle and distributed effects on connectivity within networks, rather than by taking the stimulated area "offline".