Figure 1.
Schematic diagram of experimental protocol.
Counterregulatory hormone levels, hypoglycemic symptom scores and rCBF measurements were obtained during the hyperinsulinemic euglycemic – hypoglycemic clamp. rCBF measurements were obtained using PASL-MRI and [15O]water PET for healthy individuals (n = 9).
Figure 2.
Free Surfer regions of interest.
Free Surfer maps of ROI used for this analysis. A) Sagittal (top) B) Axial (bottom) view of Freesurfer ROIs. Blue: globus pallidum, Green: caudate, Dark Green: lateral prefrontal cortex, Magenta: medial prefrontal cortex.
Table 1.
Mean (±SE) plasma glucose and counterregulatory hormones at baseline and at time of CBF acquisition for euglycemic and hypoglycemic clamp phases and peak levels during each phase.
Figure 3.
Qualitative cerebral blood flow during hypoglycemia and euglycemia in PET and PASL-MRI.
Axial images showing the mean difference (CBF hypoglycemia – CBF euglycemia) maps from nine subjects for A) positron emission tomography (PET) and B) pulse arterial spin labeling magnetic resonance imaging (PASL-MRI). Yellow/orange represents increased and blue represents decreased blood flow during the hypoglycemic relative to euglycemic session. Similar increases in CBF for hypoglycemia were seen for both methods within the thalamus.
Figure 4.
Quantitative regional cerebral blood flow during euglycemia and hypoglycemia in PET and PASL-MRI.
Quantitative regional CBF (mL.100 g−1. min−1) responses for euglycemia (black bars) and hypoglycemia (white bars) within a previously identified network. Significant increases in CBF were seen with hypoglycemia within the thalamus (THAL), globus pallidum (GP), and medial prefrontal cortex (MPF) for both A) PET and B) PASL-MRI. No significant increases were seen in the right orbitoprefrontal cortex (ROPF). *p<0.05.