Concurrent TMS to the primary motor cortex augments slow motor learning

Abstract

Transcranial magnetic stimulation (TMS) has shown promise as a treatment tool, with one FDA approved use. While TMS alone is able to up- (or down-) regulate a targeted neural system, we argue that TMS applied as an adjuvant is more effective for repetitive physical, behavioral and cognitive therapies, that is, therapies which are designed to alter the network properties of neural systems through Hebbian learning. We tested this hypothesis in the context of a slow motor learning paradigm. Healthy right-handed individuals were assigned to receive 5 Hz TMS (TMS group) or sham TMS (sham group) to the right primary motor cortex (M1) as they performed daily motor practice of a digit sequence task with their non-dominant hand for 4 weeks. Resting cerebral blood flow (CBF) was measured by normalH215O PET at baseline and after 4 weeks of practice. Sequence performance was measured daily as the number of correct sequences performed, and modeled using a hyperbolic function. Sequence performance increased significantly at 4 weeks relative to baseline in both groups. The TMS group had a significant additional improvement in performance, specifically, in the rate of skill acquisition. In both groups, an improvement in sequence timing and transfer of skills to non-trained motor domains was also found. Compared to the sham group, the TMS group demonstrated increases in resting CBF specifically in regions known to mediate skill learning namely, the M1, cingulate cortex, putamen, hippocampus, and cerebellum. These results indicate that TMS applied concomitantly augments behavioral effects of motor practice, with corresponding neural plasticity in motor sequence learning network. These findings are the first demonstration of the behavioral and neural enhancing effects of TMS on slow motor practice and have direct application in neurorehabilitation where TMS could be applied in conjunction with physical therapy.

Explaining Individual Differences in Motor Behavior by Intrinsic Functional Connectivity and Corticospinal Excitability

“…Electromyography data were measured from the left first dorsal interosseous (FDI) muscle (Rossini et al, 1994), corresponding to the main behavioral task performed with subjects' nondominant left hand. MEP recordings of the FDI muscle are the most common measurement for motor corticospinal excitability, and have been reported in previous studies (for example see Di Lazzaro et al, 1998;Tunovic et al, 2014;Volz et al, 2014, along with most of the TMS studies using the finger tapping task, which measured MEP from the FDI to set the motor threshold such as Perez et al, 2007;Censor et al, 2014b;Narayana et al, 2014). Two 10 mm diameter Ag/AgCl surface electrodes were placed on the left FDI muscle, and one additional ground electrode was placed on subjects' left ulnar tuberosity.…”

“…Could behavior be predicted from an integration of neural measurements acquired prior to task performance? Execution of a motor task requires multiple levels of precise neural processes involving motor planning, motor control and skill acquisition at the central nervous system (Allen et al, 1997;Braitenberg et al, 1997;Muellbacher et al, 2002;Hanakawa et al, 2008;Cohen et al, 2009;Narayana et al, 2014;Gabitov et al, 2016), transformation of the motor command along the corticospinal tract to the peripheral nervous system (Rossini et al, 1994;Di Lazzaro et al, 1998;Groppa et al, 2012), and a correct execution of the movement by the corresponding peripheral muscle.…”

Using brain stimulation to disentangle neural correlates of conscious vision

“…When it comes to NIBS, while parietal disruption leads to effects (see above), we are not aware of studies demonstrating functional relevance of frontal regions for spontaneous perceptual reversals in passive bistable vision so far. (Virtual) lesions of frontal cortex appeared to affect voluntarily induced reversal rates, though no such effect on passive viewing reversals was found (Windmann et al, 2006; de Graaf et al, 2011b). Yet the frontal lobe is large and null results remain fundamentally limited (de Graaf and Sack, 2011).…”

Repetitive transcranial magnetic stimulation improves both hearing function and tinnitus perception in sudden sensorineural hearing loss patients

“…A 555 MBq dose of 99m Tc-ECD was injected again 100 s after scanning. The data collection, imaging reconstruction and measurement of rCBF were performed according to previously reported methods 60 . Two experienced physicians from the Department of Nuclear Medicine confirmed the foci displaying decreased rCBF according to the reference criteria for an anomalous image of cerebral perfusion 61 .…”