Changes in GABA and Glutamate levels with peripheral and central visual stimulation using functional magnetic resonance spectroscopy at 7T

Motivation: Changes in GABA and Glutamate associated with positive/negative BOLD activation in the visual cortex due to central and peripheral stimulation of the visual field are measured with functional MRS. Goal(s): How does stimulation of the central visual field affects concentrations of excitatory and inhibitory neurotransmitters and could these changes be consistent with negative and positive BOLD activation? Approach: An fMRS paradigm was applied on four volunteers to measure average changes in GABA and Glu due to alternating periods of central and peripheral visual stimulation, using a non-edited semi-LASER sequence. Results: GABA decreased on average with peripheral stimulation while Glutamate showed an inconsistent trend. Impact: Indirect effects of negative and positive BOLD activation can be explored with functional MRS by measuring changes of GABA (inhibitory) and Glutamate (excitatory) neurotransmitters in the visual cortex resulting from central and peripheral stimulation of the visual field.