Effects of overnight fasting on working memory‐related brain network: An fMRI study

Abstract

Glucose metabolism serves as the central source of energy for the human brain. Little is known about the effects of blood glucose level (BGL) on higher-order cognitive functions within a physiological range (e.g., after overnight fasting). In this randomized, placebo-controlled, double blind study, we assessed the impact of overnight fasting (14 h) on brain activation during a working memory task. We sought to mimic BGLs that occur naturally in healthy humans after overnight fasting. After standardized periods of food restriction, 40 (20 male) healthy participants were randomly assigned to receive either glucagon to balance the BGL or placebo (NaCl). A parametric fMRI paradigm, including 2-back and 0-back tasks, was used. Subclinically low BGL following overnight fasting was found to be linked to reduced involvement of the bilateral dorsal midline thalamus and the bilateral basal ganglia, suggesting high sensitivity of those regions to minimal changes in BGLs. Our results indicate that overnight fasting leads to physiologically low levels of glucose, impacting brain activation during working memory tasks even when there are no differences in cognitive performance.

Cognitive influence of a 5-h ENERGY® shot:Are effects perceived or real?

“…In a study by Green et al [24], there were no significant effects of three levels of food deprivation (one missed meal, two missed meals, no food for 24-hours prior to testing) on sustained attention, attentional focus, simple reaction time, and immediate memory. Another study [25] also supports the notion that short-term fasting (up to 24 hours) does not significantly affect cognitive performance. The avoidance of food intake prior to testing was important to not only isolate 5-HES effects on cognitive performance, but also lessen the benefits of glucose facilitation on cognition [26][27].…”

Fasting enhances extinction retention and prevents the return of fear in humans

“…Overnight fasting for 12–14 h has been commonly used to detect relationships between fasting and cognition in humans 31 , 32 . Imaging findings showed that 14 or 16 h of overnight fasting significantly increased the activation of brain areas that are related to cognition 23 , 28 . Considering this, we imposed a fasting duration of 16 h in the present study.…”

“…Huang et al 21 suggested that acute fasting in mice enhanced fear extinction by activating ghrelin signaling in the amygdala. In humans, fasting may impact brain activation during working memory tasks and performance in several cognitive domains 23 , 24 . The present study investigated the effects of short-term fasting on fear acquisition, extinction, and the return of fear and developed an enhanced extinction retention training interference procedure to eliminate fear responses in humans.…”

The functional anatomy of cognitive control: A domain‐general brain network for uncertainty processing

“…This large‐scale network has been considered as the “cognitive control network” (CCN) (Fan, ; Niendam et al, ; Wu et al, , ). Abundant evidence exists showing that the regions of the CCN co‐activate in the Flanker and Color‐Word Stroop conflict tasks (e.g., Brass, Derrfuss, & von Cramon, ; Fan et al, ; van Veen & Carter, ), Go/No‐Go tasks (e.g., Blasi et al, ; Cai, Ryali, Chen, Li, & Menon, ; Schulz, Bedard, Czarnecki, & Fan, ; Sebastian, Pohl, et al, ), N‐back tasks (e.g., Chechko et al, ; Glabus, ), and choice selection tasks (e.g., K.‐M. Lee, Wade, & Lee, ; Wu et al, ).…”

“…This large-scale network has been considered as the "cognitive control network" (CCN) (Fan, 2014;Niendam et al, 2012;Wu et al, 2018Wu et al, , 2019. Abundant evidence exists showing that the regions of the CCN co-activate in the Flanker and Color-Word Stroop conflict tasks (e.g., Fan et al, 2003;van Veen & Carter, 2005), Go/No-Go tasks (e.g., Blasi et al, 2006;Cai, Ryali, Chen, Li, & Menon, 2014;Schulz, Bedard, Czarnecki, & Fan, 2011;Sebastian, Pohl, et al, 2013), Nback tasks (e.g., Chechko et al, 2015;Glabus, 2003), and choice selection tasks (e.g., K.-M. Lee, Wade, & Lee, 2006;Wu et al, 2018). Functions of specific regions of this network have been linked to distinct cognitive processes, such as conflict monitoring and resolution (Botvinick, Braver, Barch, Carter, & Cohen, 2001;Botvinick, Cohen, & Carter, 2004;Fan, Hof, Guise, Fossella, & Posner, 2008;Fan et al, 2007;Yeung, Cohen, & Botvinick, 2011), working memory updating (D'Esposito et al, 1998), and motor generation (Grinband et al, 2011).…”