Sensorimotor Cortex Gamma-Aminobutyric Acid Concentration Correlates with Impaired Performance in Patients with MS

P.K Bhattacharyya,M.D Phillips,M.J Lowe,R.A Bermel,L.A Stone

doi:10.3174/ajnr.a3483

Abstract

Abnormalities in GABA concentration [GABA] have been associated with several neuropsychiatric disorders, and research has suggested that GABA may play a role in sensorimotor cortex function. We sought to determine whether identifying a change in [GABA] within the sensorimotor cortex of patients with MS has any effect on motor function and would provide information about the adaptive/compensatory mechanisms involved in the attempt to maintain motor function during disease progression. In 19 healthy controls and 30 patients with MS, we assessed task performance with the MS Functional Composite scale and its components (T25FW test, 9HPT, and PASAT). With in vivo MR spectroscopy, we measured [GABA] in the sensorimotor cortex and determined correlations between [GABA] and task performance. We also assessed the association between [GABA] and cortical activation volume after a bilateral finger-tapping task. [GABA] was inversely correlated with 9HPT scores in patients with MS, indicating a worsening of performance with increased [GABA]. No significant correlation was observed between [GABA] and T25FW or PASAT scores. [GABA] was directly correlated with primary motor cortex activation volume after the finger-tapping task in patients with MS. These results suggest that cortical [GABA] may be a marker of function and reorganization/adaptation of cortical gray matter in MS.

Highlights

BACKGROUND AND PURPOSEAbnormalities in GABA concentration [GABA] have been associated with several neuropsychiatric disorders, and research has suggested that GABA may play a role in sensorimotor cortex function
GABAergic inhibition has been identified as one of the mechanisms operating in use-dependent plasticity in the intact human motor cortex, which suggests similarities between the mechanisms underlying this form of plasticity and long-term potentiation.[2]
The GABA agonist lorazepam is associated with suppression of profound reorganization in the somatosensory cortex, as demonstrated with motor-learning paradigms.8 [GABA] reduction in the sensorimotor cortex of healthy controls during motor learning has been reported[5]; and decreases in [GABA] in the sensorimotor cortex have been observed in patients with focal dystonia.[6]

Summary

Introduction

BACKGROUND AND PURPOSEAbnormalities in GABA concentration [GABA] have been associated with several neuropsychiatric disorders, and research has suggested that GABA may play a role in sensorimotor cortex function. We sought to determine whether identifying a change in [GABA] within the sensorimotor cortex of patients with MS has any effect on motor function and would provide information about the adaptive/compensatory mechanisms involved in the attempt to maintain motor function during disease progression

Methods

Results

Discussion

Conclusion