Is visual activation associated with changes in cerebral high-energy phosphate levels?

• Published in: Brain Structure and Function Vol. 223; no. 6; pp. 2721 - 2731
• Main Authors: van de Bank, Bart L., Maas, Marnix C., Bains, Lauren J., Heerschap, Arend, Scheenen, Tom W. J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2018; Springer Nature B.V
• Subjects: Adult; Biomedical and Life Sciences; Biomedicine; Brain Mapping; Cell Biology; Cortex (temporal); Energy Metabolism - physiology; Female; Functional magnetic resonance imaging; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Neuroimaging; Neurology; Neurosciences; Original; Original Article; Oxygen - blood; Phosphates - metabolism; Phosphocreatine; Phosphorus; Photic Stimulation - methods; Rest; Visual cortex; Visual Cortex - diagnostic imaging; Visual Cortex - metabolism; Visual Cortex - physiology; Visual stimuli; Young Adult; Functional magnetic resonance spectroscopy; Human brain; In vivo; P MRS; Energy metabolism; Phosphocreatine (PCr); In vivo 31P MRS
• ISSN: 1863-2653; 1863-2661; 0340-2061
• DOI: 10.1007/s00429-018-1656-7

Phosphorus magnetic resonance spectroscopy ( 31 P MRS) has been employed before to assess phosphocreatine (PCr) and other high-energy phosphates in the visual cortex during visual stimulation with inconsistent results. We performed functional 31 P MRS imaging in the visual cortex and control regions during a visual stimulation paradigm at an unprecedented sensitivity, exploiting a dedicated RF coil design at a 7 T MR system. Visual stimulation in a 3 min 24 s on–off paradigm in eight young healthy adults generated a clear BOLD effect with traditional 1 H functional MRI in the visual cortex (average z  score 9.9 ± 0.2). However, no significant event-related changes in any of the 31 P metabolite concentrations, linewidths (7.9 ± 1.8 vs 7.8 ± 1.9 Hz) or tissue pH (7.07 ± 0.13 vs 7.06 ± 0.07) were detectable. Overall, our study of 31 P MRSI in 15 cm 3 voxels had a detection threshold for changes in PCr, Pi and γ-ATP between stimulation and rest of 5, 17 and 10%, respectively. In individual subjects, the mean coefficients of variance for PCr and Pi levels of control voxels were 6 ± 3 and 19 ± 8% (three time point average of 3 min 24 s). Altogether this indicates that energy supply for neuronal activation at this temporal resolution does not drain global PCr resources.