Effects of prefrontal theta burst stimulation on neuronal activity and subsequent eating behavior: an interleaved rTMS and fNIRS study

Abstract

The dorsolateral prefrontal cortex (dlPFC) and dorsomedial prefrontal cortex (dmPFC) are important nodes for self-control and decision-making, but through separable processes (cognitive control versus evaluative processing). This study aimed to examine the effects of excitatory brain stimulation (intermittent theta-burst stimulation; iTBS) targeting the dlPFC and dmPFC on food choice. iTBS was hypothesized to decrease consumption of appetitive snack foods, via enhanced interference control for dlPFC stimulation and reduced delay discounting for dmPFC stimulation. Using a single-blinded, between-subjects design, participants (N = 43) were randomly assigned to of the three conditions: 1) iTBS targeting the left dlPFC, 2) iTBS targeting bilateral dmPFC, or 3) sham. Participants then completed two cognitive tasks (delay discounting (DD) and Flanker), followed by a taste test. fNIRS imaging revealed increases in medial PFC activity were evident in the dmPFC stimulation group during the DD task; likewise, a neural efficiency effect was observed in the dlPFC stimulation group during the Flanker. Gender significantly moderated consumption during the taste test, with females in the dmPFC showing paradoxical increases in food consumption compared to sham. Findings are consistent with possible amplification of positive evaluative processing in the presence of dietary restraint, vis-à-vis excitation of the mPFC.

Brain functional and structural magnetic resonance imaging of obesity and weight loss interventions

“…In a recent imaging study, rTMS induced weight loss, increased betweenness centrality (the degree to which a region influences information flow across the brain, based on how many other regions have short paths connecting to it) within FPN and MOFC, and decreased degree centrality in the occipital pole [134,226]. In addition, DMPFC rTMS increased activation over the stimulation site during a delay discounting task [227]. tDCS over DLPFC decreased activation in the ventral striatum in responses to food cue [133].…”

Real-time motion-enabling positron emission tomography of the brain of upright ambulatory humans

“…In contrast, for motion-tolerant imagers, brain activity information is diminished or missing from brain regions like basal nuclei, hippocampus, and limbic regions critically involved in motor, balance, social, and emotional tasks. HD-DOT and fNIRS technologies have allowed for natural movement and behaviors such as walking 14 , eating behaviors 15 , and social interaction 16 . However, the optical light mechanisms of these modalities only penetrate a short distance into the brain, leaving unseen the activity in deep brain structures known to be critical for balance, reward, addiction, memory, and other clinically-relevant functions affected by neurological injuries or diseases 17,18 .…”

“…This makes advances in ambulatory PET technology appealing for monitoring pharmaceutical alterations in the brain, while enabling research with moving participant populations and ecologically-valid paradigms. Whole brain PET imaging paradigm adaptations have allowed for human behavioral tasks that require motion, including repeated O 15 -H 2 O injections 21 , but are limited by the higher activity exposure of this ligand and requirements of having a very close-by cyclotron 22,23 . Next, Delayed-PET studies inject research participants outside of the PET scanner just before performing a task that cannot be performed in the scanner, with metabolic markers like Fluorodeoxyglucose (F 18 -FDG) or neurotransmitter specific ligands like C 11 -raclopride (a neuroreceptor agonist for dopamine D2 receptors), with the ligand uptake changes occurring during the task.…”