Excitation and inhibition; the Yin and Yang of functional brain connectivity?

Resting-state functional MRI (fMRI) is increasingly being used to study normal and abnormal functioning of the brain. Regions with synchronized blood oxygenation level-dependent (BOLD) signals, measured with resting-state fMRI, are considered to be functionally connected. Despite strong indications of functional connectivity changes in diseased brains, the neurophysiological basis of functional connectivity remains largely unresolved. The neural activity that is supposed to underlie functional connectivity hinges on the excitation-inhibition balance in the brain. Measuring excitatory and inhibitory neurotransmitter dynamics may therefore provide a promising entry to better understand functional connectivity in the healthy brain, and functional connectivity changes in brain pathology. Therefore, I aim to map the glutamatergic and GABAergic neurotransmitter cycling rates in the functionally connected sensorimotor cortices in healthy adult rats with high-field magnetic resonance spectroscopy (MRS). An exchange visit would offer a great opportunity to learn all (theoretical and practical) aspects of acquisition and analysis of 1H-[13C] MRS data, and to apply this in combination with resting-state fMRI. After the experiments performed at the Yale Magnetic Resonance Research Center, we aim to perform similar 1H-[13C] MRS experiments in our animal models of stroke in Utrecht, in collaboration with our Yale colleagues, to investigate the neurometabolic underpinnings of stroke.