Regionally Specific Regulation of Sensorimotor Network Connectivity Following Tactile Improvement.

Stefanie Heba,Benjamin Glaubitz,Melanie Lenz,Oliver Höffken,Martin Tegenthoff,Tobias Kalisch,Lauren M Schweizer,Nicolaas A J Puts,Tobias Schmidt-Wilcke,Hubert R Dinse

doi:10.1155/2017/5270532

Abstract

Correlations between inherent, task-free low-frequency fluctuations in the blood oxygenation level-dependent (BOLD) signals of the brain provide a potent tool to delineate its functional architecture in terms of intrinsic functional connectivity (iFC). Still, it remains unclear how iFC is modulated during learning. We employed whole-brain resting-state magnetic resonance imaging prior to and after training-independent repetitive sensory stimulation (rSS), which is known to induce somatosensory cortical reorganization. We investigated which areas in the sensorimotor network are susceptible to neural plasticity (i.e., where changes in functional connectivity occurred) and where iFC might be indicative of enhanced tactile performance. We hypothesized iFC to increase in those brain regions primarily receiving the afferent tactile input. Strengthened intrinsic connectivity within the sensorimotor network after rSS was found not only in the postcentral gyrus contralateral to the stimulated hand, but also in associative brain regions, where iFC correlated positively with tactile performance or learning. We also observed that rSS led to attenuation of the network at higher cortical levels, which possibly promotes facilitation of tactile discrimination. We found that resting-state BOLD fluctuations are linked to behavioral performance and sensory learning, indicating that network fluctuations at rest are predictive of behavioral changes and neuroplasticity.

Highlights

The acquisition of new skills, or the recovery of function after damage to the central nervous system, requires changes in neuronal connections
We investigated which areas in the sensorimotor network are susceptible to neural plasticity and where intrinsic functional connectivity (iFC) might be indicative of enhanced tactile performance
As we reported in our previous study [32], after 45 min of intermittent high-frequency stimulation of all fingers of the right hand, tactile discrimination performance of the stimulated index finger—in terms of 2-point discrimination (2ptD) thresholds—improved by 12% on average (Base: 1.59 ± 0.03 mm, performed 45–90 min after rSS intervention (Post): 1.38 ± 0.05 mm; dCohen: 5.093), while performance of the nonstimulated left hand index finger remained unaltered, confirming previously reported selective improvements after repetitive sensory stimulation (rSS) [34]

Summary

Introduction

The acquisition of new skills, or the recovery of function after damage to the central nervous system, requires changes in neuronal connections. RSN have been in the focus of scientific research ever since Biswal et al [16] showed the spatial congruency between regions activated during task-related functional magnetic resonance imaging (fMRI) and regions with highly correlated low-frequency. A logical consequence is to utilize resting-state fMRI to investigate learning-induced plasticity, which is reflected in changes in task-free BOLD fluctuations after training and/or learning. This method has been successfully employed for both healthy controls [11, 17, 18] and patients with stroke or carpal tunnel syndrome [19, 20]

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Conclusion