Prefronto-cerebellar neuromodulation affects appetite in obesity

Abstract

Human neuroimaging studies have consistently reported changes in cerebellar function and integrity in association with obesity. To date, however, the nature of this link has not been studied directly. Emerging evidence suggests a role for the cerebellum in higher cognitive functions through reciprocal connections with the prefrontal cortex. The purpose of this exploratory study was to examine appetite changes associated with noninvasive prefronto-cerebellar neuromodulation in obesity. Totally, 12 subjects with class I obesity (mean body mass index 32.9 kg/m²) underwent a randomized, single-blinded, sham-controlled, crossover study, during which they received transcranial direct current stimulation ((tDCS); active/sham) aimed at simultaneously enhancing the activity of the prefrontal cortex and decreasing the activity of the cerebellum. Changes in appetite (state and food-cue-triggered) and performance in a food-modified working memory task were evaluated. We found that active tDCS caused an increase in hunger and desire to eat following food-cue exposure. In line with these data, subjects also tended to make more errors during the working memory task. No changes in basic motor performance occurred. This study represents the first demonstration that prefronto-cerebellar neuromodulation can influence appetite in individuals with obesity. While preliminary, our findings support a potential role for prefronto-cerebellar pathways in the behavioral manifestations of obesity.

Figure 1.

A. tDCS montage used in the present study. 5×5 cm electrode pads were placed over right cerebellum (cathode) and F3 (anode). B. Computational model of the tDCS montage used. Peak electric field magnitude is shown at the approximate location of the electrodes (axial images, white circles). The scale bar on the right shows the color code for current density values (V/m). C. Study diagram showing the time course of measurements for each of the study visits. VAS: visual analogue scale.

Figure 2.

Box and dot plots representing changes in the four VAS scores (Δ, columns) for the two appetite measurements: state and cue-triggered (rows). The horizontal line represents a significant main effect of stimulation condition (active vs. sham) and the asterisks (*) over one condition represent significant pre-post differences within that condition.