The influence of the subcortex and brain stem on overeating: How advances in functional neuroimaging can be applied to expand neurobiological models to beyond the cortex

Abstract

Functional neuroimaging has become a widely used tool in obesity and eating disorder research to explore the alterations in neurobiology that underlie overeating and binge eating behaviors. Current and traditional neurobiological models underscore the importance of impairments in brain systems supporting reward, cognitive control, attention, and emotion regulation as primary drivers for overeating. Due to the technical limitations of standard field strength functional magnetic resonance imaging (fMRI) scanners, human neuroimaging research to date has focused largely on cortical and basal ganglia effects on appetitive behaviors. The present review draws on animal and human research to highlight how neural signaling encoding energy regulation, reward-learning, and habit formation converge on hypothalamic, brainstem, thalamic, and striatal regions to contribute to overeating in humans. We also consider the role of regions such as the mediodorsal thalamus, ventral striatum, lateral hypothalamus and locus coeruleus in supporting habit formation, inhibitory control of food craving, and attentional biases. Through these discussions, we present proposals on how the neurobiology underlying these processes could be examined using functional neuroimaging and highlight how ultra-high field 7-Tesla (7 T) fMRI may be leveraged to elucidate the potential functional alterations in subcortical networks. Focus is given to how interactions of these regions with peripheral endocannabinoids and neuropeptides, such as orexin, could be explored. Technical and methodological aspects regarding the use of ultra-high field 7 T fMRI to study eating behaviors are also reviewed.

The influence of stress on the neural underpinnings of disinhibited eating: a systematic review and future directions for research

“…Similarly, another study by Simon et al [ 88 ] found that individuals with binge-eating spectrum disorders display diminished recruitment of the posterior cingulate cortex when anticipating food reward, and increased activation of the posterior cingulate cortex and anterior medial prefrontal cortex during receipt. These findings align with an alternative suggested mechanism for DE, wherein repeated consumption of energy-dense foods may eventually desensitise reward circuitry [ 89 ]. In turn, DE behaviours may continue as a means of overcoming diminished mesocorticolimbic responsivity to such foods.…”

Dynamic fronto‐amygdalar interactions underlying emotion‐regulation deficits in women at higher weight

“…In relation to our DCM analyses, this hypothesis‐driven technique relies on a priori assumptions on which brain regions to include in a model space and is therefore limited in the number of regions that can be evaluated. In this sense, the dual opposing system mechanism mentioned previously does not fully capture the nuances of recent findings suggesting the involvement of thalamic and subcortical hubs during affect processing and model‐based cognition [42] or include subcortical regions proposed to contribute to overeating [43]. For instance, alterations in insula‐prefrontal connectivity have been associated with emotion‐regulation deficits in individuals at high weight and could be investigated using DCM in the future [6].…”

Effects of Fructose and Palmitic Acid on Gene Expression in Drosophila melanogaster Larvae: Implications for Neurodegenerative Diseases

“…The decrease in glycine has a direct effect on the balance of neurotransmitters, which causes alterations in the brain stem in rats [ 49 ]. This has been associated with diseases such as the impaired regulation of attention, emotions, and cognitive control, which are common in patients with overeating [ 50 ]. Therefore, the decrease in threonine induced by the MD could be related to the decrease in glycine and the mechanisms that lead to the development of these alterations in patients with overfeeding [ 50 ].…”