The relationship between glutamate and oscillatory activity in a repetition suppression paradigm ? a combined MR-spectroscopy and EEG study

stimuli to be seen. Average Glu levels were found to be lower after real stimuli presentation compared to abstract stimuli (p=0.02). A significant correlation between Glu levels and the eGBA was also found (figure 1b). Conclusions These results provide the first simultaneously recorded in-vivo evidence of changes in neuronal electrical activity with related changes in Glu concentrations, and provide a window into the underlying neurochemical substrates of neuronal network activity. References 1. Gruber, T., & Müller, M. M. (2005). Oscillatory brain activity dissociates between associative stimulus content in a repetition priming task in the human EEG.Cerebral Cortex, 15, 109-116. 2. Muthukumaraswamy, S. D., Edden, R. A. E., Jones, D. K., Swettenham, J. B., & Singh, K. D. (2009). Resting GABA concentration predicts peak gamma frequency and fMRI amplitude in response to visual stimulation in humans. PNAS, 106(20), pp. 8356-8361. 3. Naressi, A., Couturier, C., Castang, I., de Beer, R. Graveron-Demilly, D. Java-based graphical user interface for MRUI, a software package for quantitation of in vivo/medical magnetic resonance spectroscopy signals. Computers in Biology and Medicine 31: 269-86, 2001. Figure 1 a) representative MRS data used in the analysis, b) relationship between Glu levels and evoked Gama band responses for both conditions. a