The neural substrates of subliminal attentional bias and reduced inhibition in individuals with a higher BMI: A VBM and resting state connectivity study

• Published in: NeuroImage (Orlando, Fla.) Fla.), 2021-04, Vol.229, p.117725-117725, Article 117725
• Main Authors: Osimo, S.A., Piretti, L., Ionta, S., Rumiati, R.I., Aiello, M.
• Format: Article
• Language: English
• Subjects: Bias; Body mass index; Body weight; Eating disorders; Ethics; Food; Go/no-go discrimination learning; Impulsive behavior; Information processing; Inhibition; Investigations; Magnetic resonance imaging; Morphometry; Neural networks; Obesity; Occipital lobe; Operculum; Overweight; Questionnaires; Reinforcement; Resting-state connectivity; Sensory integration; Somatosensory cortex; Subliminal attention; Substantia grisea; Temporal cortex; Voxel-based morphometry
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2021.117725

•Higher BMI is linked to slower subliminal processing of food and nonfood images.•This correlates with lower GM density in the OFC, temporal areas, operculum/insula.•Higher BMI predicts reduced inhibition for food in the Go/No-Go task.•Reduced inhibition for food correlates with lower GM density in reward areas.•It also correlates with lower connectivity of the orbital gyrus to visual areas. Previous studies have shown that individuals with overweight and obesity may experience attentional biases and reduced inhibition toward food stimuli. However, evidence is scarce as to whether the attentional bias is present even before stimuli are consciously recognized. Moreover, it is not known whether or not differences in the underlying brain morphometry and connectivity may co-occur with attentional bias and impulsivity towards food in individuals with different BMIs. To address these questions, we asked fifty-three participants (age M = 23.2, SD = 2.9, 13 males) to perform a breaking Continuous Flash Suppression (bCFS) task to measure the speed of subliminal processing, and a Go/No-Go task to measure inhibition, using food and nonfood stimuli. We collected whole-brain structural magnetic resonance images and functional resting-state activity. A higher BMI predicted slower subliminal processing of images independently of the type of stimulus (food or nonfood, p = 0.001, εp2 = 0.17). This higher threshold of awareness is linked to lower grey matter (GM) density of key areas involved in awareness, high-level sensory integration, and reward, such as the orbitofrontal cortex [t = 4.55, p = 0.003], the right temporal areas [t = 4.18, p = 0.002], the operculum and insula [t = 4.14, p = 0.005] only in individuals with a higher BMI. In addition, individuals with a higher BMI exhibit a specific reduced inhibition to food in the Go/No-Go task [p = 0.02, εp2 = 0.02], which is associated with lower GM density in reward brain regions [orbital gyrus, t = 4.97, p = 0.005, and parietal operculum, t = 5.14, p < 0.001] and lower resting-state connectivity of the orbital gyrus to visual areas [fusiform gyrus, t = -4.64, p < 0.001 and bilateral occipital cortex, t = -4.51, p < 0.001 and t = -4.34, p < 0.001]. Therefore, a higher BMI is predictive of non food-specific slower visual subliminal processing, which is linked to morphological alterations of key areas involved in awareness, high-level sensory integration, and reward. At a late, conscious stage of visual processing a higher