Glutamatergic response to a low load working memory paradigm in the left dorsolateral prefrontal cortex in patients with mild cognitive impairment: a functional magnetic resonance spectroscopy study

  • Anupa A. Vijayakumari
  • Ramshekhar N. Menon
  • Bejoy Thomas
  • Thumboli Muyyayil Arun
  • Mohanan Nandini
  • Chandrasekharan KesavadasEmail author


Working memory deficits have been widely reported in mild cognitive impairment (MCI). However, the neural mechanisms of working memory dysfunction in MCI have not been clearly understood. In this study, we used proton functional magnetic resonance spectroscopy (1H-fMRS) and functional magnetic resonance imaging (fMRI) to understand the underlying neurobiology of working memory deficits in patients with MCI. We aimed at detecting the changes in the concentration of glutamate and blood oxygen level dependent (BOLD) activity using 1H-fMRS and fMRI respectively during a low load verbal (0 back and 1 back) working memory in the left dorsolateral prefrontal cortex (DLPFC) between patients with MCI and healthy controls. Fifteen patients with amnestic MCI and twenty two age, gender and education matched healthy controls underwent a low load verbal working memory 1H-fMRS and fMRI. We observed significant increase in glutamate during working memory task (both 0 back and 1 back) in healthy controls and such changes were absent in patients with MCI. However, percent signal changes representing BOLD activity during both 0 back and 1 back was not significantly different between two groups. Our findings suggest that 1H-fMRS complements fMRI in understanding the working memory mechanism in the left DLPFC.


Working memory Functional magnetic resonance spectroscopy Functional magnetic resonance imaging Glutamate neurotransmission Mild cognitive impairment 



The study was financially supported by the Science and Engineering Research Board, Department of Science and Technology, India (Grant no. PDF/2016/000494 dated 28 November 2016 to Dr. Anupa A Vijayakumari). The authors express their deep sense of gratitude to all the research participants who graciously took part in this project, as well as the staff of the Department of Imaging Sciences and Technology at SCTIMST. In addition, we specifically thank Mr. Jithin B and Ms. Anusree TV for their technical assistance


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Authors and Affiliations

  1. 1.Medical Image Processing Laboratory, Department of Imaging Sciences and Interventional Radiology (IS & IR)Sree Chitra Tirunal Institute for Medical Sciences and TechnologyTrivandrumIndia
  2. 2.Department of NeurologySree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST)TrivandrumIndia

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