Brain-mapping techniques for evaluating poststroke recovery and rehabilitation: a review

Proton magnetic resonance spectroscopy (1H-MRS) reveals the presence of elevated myo-inositol in the occipital cortex of blind subjects

This paper is addressed to investigate whether proton magnetic resonance spectroscopy ((1)H-MRS) may provide the means to investigate changes associated to alterations of neural activity and sensory experience in the blind. We examined the relationships between different brain metabolite levels in 10 blind volunteers and 10 sighted subjects matched for age and gender. Adjusted levels of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), glutamate/glutamine (Glx) and myo-inositol (mIno) in the occipital cortex region were quantified in the water-suppressed spectrum using the AMARES estimation algorithms. An unpaired two-tailed t-test was used to determine any significant difference in metabolite ratios. Our results show that none of the blind volunteers presented atrophy or any other MRI detectable degenerative change of the occipital cortex. The main finding was a significant increase of myo-inositol (mIno), a glial marker, in blind subjects compared to sighted controls. This simple sugar-like molecule can be found mainly within astrocytes, and cannot cross the blood-brain barrier. Therefore its increase could reflect glial proliferation or an increase in glial cell size. These results show that (1)H-MRS may help to understand the complex mechanisms involved in brain plasticity and suggest an active role of glial cells in the reorganization of the brain in response to visual deprivation.