1. Volume 136, Issue 2, Pages 417-424 (February 2009)
A Magnetic Resonance Spectroscopy Study of Brain Glutamate in a Model of Plasticity in Human Pharyngeal Motor Cortex 
Salil Singh, Satish Mistry, Samantha Jefferson, Karen Davies, John Rothwell, Stephen Williams, Shaheen Hamdy 
Gastroenterology 
Volume 136, Issue 2, Pages (February 2009)
DOI: /j.gastro
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2. Figure 1
Sample pharyngeal motor evoked potentials. Data from one individual showing pharyngeal EMG traces in response to TMS. Traces are averages of 10 responses at suprathreshold intensity before and 120 minutes after PAS. ISIs of 50, 75, 100, and 125 ms are displayed. PAS at an ISI of 100 ms resulted in the greatest changes in EMG amplitude.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions

3. Figure 2
Effects of PAS on pharyngeal motor cortex excitability. Group mean percentage change in PMEP amplitude after PAS with ISIs of 50, 75, 100, and 125 ms. Results are plotted as mean data across all intensities ± SEM. PAS at an ISI of 100 ms produced an increase in cortical excitability that was sustained throughout the postintervention recording period (*P ≤ .002, post hoc t tests). No significant changes were evident with the other ISIs. bl, baseline.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions

4. Figure 3
Effects of PAS on the contralateral hemisphere. Group mean percentage change in PMEP amplitude (± SEM) at the ipsilateral and contralateral pharyngeal motor cortices after PAS at an ISI of 100 ms. bl, baseline.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions

5. Figure 4
Sample of time-domain fitting for MRS data. (A) Representative magnetic resonance spectrum with estimated peaks and residual trace calculated by the AMARES analysis method (jMRUI 2.1, EU project).17 (B) Magnified section of the same data in the 2- to 3-ppm range with arrows marking the estimated glutamate peaks. Assignments: 1, NAA-1 (methyl group); 2, creatine + phosphocreatine (methyl groups); 3, choline-containing compounds; 4, myo-inositol + glycine; 5, myo-inositol; 6, creatine + phosphocreatine (methylene groups); 7, glutamate + glutamine (C3 protons); 8 and 9, glut-1, glut-2 (C4 protons); 10, glut-3 and glutamine-1 (C4 protons); 11, glutamine; 12, NAA (aspartyl group); 13, aspartate; 14, scyllo-inositol; and 15, amino acid amine groups (mainly glutamate and glutamine).
Gastroenterology  , DOI: ( /j.gastro )
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6. Figure 5
Glutamate ratio changes after PAS measured by MRS. (A) Glut-1/NAA-1 ratio (group mean across all time points ± SEM) at the ipsilateral pharyngeal motor cortex and occipital cortex after real or sham PAS at an ISI of 100 ms. An average reduction of approximately 25% is seen in cortical Glut-1/NAA-1 ratio levels at the stimulated site after real PAS compared with sham PAS (*P ≤ .02). No significant change was seen at the occipital control site. (B) Percentage difference (group mean at each time point ± SEM) in both glutamate ratios at the ipsilateral pharyngeal motor cortex at 4 time points (from dark to light columns = immediate, 30, 60, and 90 minutes respectively). All 4 measures show their greatest changes in the early period postintervention with a gradual return towards sham PAS. This contrasts with the changes in cortical excitability after PAS at an ISI of 100 ms where the effect builds up over 2 hours. glut, glutamate.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions