Modulation of midbrain neurocircuitry by intranasal insulin

Publication date: Available online 23 March 2019Source: NeuroImageAuthor(s): Sharmili Edwin Thanarajah, Sandra Iglesias, Bojana Kuzmanovic, Lionel Rigoux, Klaas E. Stephan, Jens C. Brüning, Marc TittgemeyerAbstractInsulin modulates dopamine neuron activity in midbrain and affects processes underlying food intake behaviour, including impulsivity and reward processing. Here, we used intranasal administration and task-free functional MRI in humans to assess time- and dose-dependent effects of insulin on functional connectivity of the dopaminergic midbrain – and how these effects varied depending on systemic insulin sensitivity as measured by HOMA-IR. Specifically, we used a repeated-measures design with factors dose (placebo, 40 IU, 100 IU, 160 IU), time (7 time points during a 90 min post-intervention interval), and group (low vs. high HOMA-IR).A factorial analysis identified a three-way interaction (with whole-brain significance) with regard to functional connectivity between midbrain and the ventromedial prefrontal cortex. This interaction demonstrates that systemic insulin sensitivity modulates the temporal course and dose-dependent effects of intranasal insulin on midbrain functional connectivity. It suggests that altered insulin sensitivity may impact on dopaminergic projections of the midbrain and might underlie the dysregulation of reward-related and motivational behaviour in obesity and diabetes. Perhaps most importantly, the time courses of midbrain functional con...

Source: NeuroImage - March 24, 2019 Category: Neuroscience Source Type: research