fNIRS estimates prefrontal cortex activation following glucose load in youths with obesity

Abstract Purpose The prefrontal cortex PFC is crucial in controlling food-related impulses. Functional near-infrared spectroscopy fNIRS represents a wearable functional neuroimaging technology for measuring PFC activation in real life. Aims of the study were to examine PFC activation in fasting conditions and after an oral glucose tolerance test OGTT in resting- state R, cognitive tasks Ts conditions and explore the PFC activation relationship with insulin sensitivity index ISI in youths with obesity. Methods 28 patients’ cross-sectional study age 7—15 y. ISI was quantified by Matsuda’s Index and PFC activation as oxygenated O 2 Hb, mol/L and total tHb, mol/L hemoglobin concentration changes, in fasting and during the first 60 min of the OGTT; in resting-state condition and during cognitive tasks Ts: Verbal Fluency, Digit Span, Non-Verbal Stroop administered before Fasting-Ts, and 15 min after OGTT OGTT-Ts. 15 min OGTT-R was divided into 5 time periods P1-P2-P3-P4-P5, and cognitive tasks OGTT-Ts were then administered again. Results Dorsolateral PFC DLPFC and right frontal pole were over-activated in OGTT compared to the fasting state. Significant differences p < 0.005, false discovery rate corrected were observed: P2 O 2 Hb Left DLPFC Fasting-R: 1.47 * 10 –6 vs OGTT-R: 4.13 * 10 –6 mol/L, P3 tHb Right DLPFC Fasting-R: 1.15 * 10 –6 vs OGTT-R: 3.36 * 10 –6 mol/L, and P5 O 2 Hb Left DLPFC Fasting-R: 1.47 * 10 –6 vs OGTT-R: 4.34 * 10 –6 mol/L, tHb Right DLPFC Fasting-R: 1.15 * 10 –6 vs OGTT-R: 3.07 * 10 –6 mol/L. The change of left DLPFC activity correlated significantly with ISI r = 0.61, p < 0.001. Conclusion fNIRS enabled the non-invasive examination of the PFC hemodynamic response associated with participants’ insulin sensitivity in an ecological context. Bilateral DLPFC activation following OGTT in youths with obesity was associated with peripheral ISI. This association suggests that peripheral insulin sensitivity might reflect the PFC’s ability to control food-related behaviours.