Cognitive Neuroscience Department, SISSA, via Bonomea 265, 34136 Trieste, Italy.
Cognitive Neuroscience Department, SISSA, via Bonomea 265, 34136 Trieste, Italy; Department of Psychology and Cognitive Sciences, University of Trento, corso Bettini 84, 38068 Rovereto, Italy; Fondazione ONLUS Marica De Vincenzi, via Alessandro Manzoni, 11, 38122 Rovereto, Italy.
Neuroimage. 2021 Apr 1;229:117725. doi: 10.1016/j.neuroimage.2021.117725. Epub 2021 Jan 20.
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, ε = 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, ε = 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 BMI is associated with a specific bias towards food and with lower GM density in reward brain regions. Finally, independently of BMI, volumetric variations and connectivity patterns in different brain regions are associated with variability in bCFS and Go/No-Go performances.
先前的研究表明，超重和肥胖的个体可能对食物刺激表现出注意力偏差和抑制能力下降。然而，即使在刺激被有意识地识别之前，是否存在注意力偏差的证据还很少。此外，不同 BMI 的个体的注意力偏差和对食物的冲动是否与大脑形态和连通性的潜在差异同时存在，目前还不清楚。为了解决这些问题，我们要求 53 名参与者（年龄 M=23.2，SD=2.9，男性 13 名）执行打破连续闪光抑制（bCFS）任务，以测量潜意识处理的速度，以及使用食物和非食物刺激的 Go/No-Go 任务来测量抑制。我们收集了全脑结构磁共振图像和功能静息状态活动。较高的 BMI 预测了对图像的潜意识处理速度较慢，而与刺激类型无关（食物或非食物，p=0.001，ε=0.17）。这种意识阈值的提高与涉及意识、高级感觉整合和奖励的关键区域的灰质（GM）密度降低有关，如眶额皮层[t=4.55，p=0.003]、右颞叶区域[t=4.18，p=0.002]、脑岛和脑岛[t=4.14，p=0.005]，仅在 BMI 较高的个体中。此外，BMI 较高的个体在 Go/No-Go 任务中表现出对食物的特定抑制减少[p=0.02，ε=0.02]，这与奖励大脑区域的 GM 密度降低有关[眶额回，t=4.97，p=0.005 和顶叶脑岛，t=5.14，p<0.001]和眶额回与视觉区域的静息状态连通性降低[梭状回，t=-4.64，p<0.001 和双侧枕叶皮层，t=-4.51，p<0.001 和 t=-4.34，p<0.001]。因此，较高的 BMI 可预测非食物特异性视觉潜意识处理较慢，这与意识、高级感觉整合和奖励相关的关键区域的形态改变有关。在视觉处理的后期，有意识的阶段，较高的 BMI 与对食物的特定偏见以及奖励大脑区域的 GM 密度降低有关。最后，无论 BMI 如何，不同大脑区域的体积变化和连通模式都与 bCFS 和 Go/No-Go 表现的可变性相关。
