[Role of the prefrontal cortex in human behavioral adaptation]

The Effects of Using a Cycling Desk at School on Executive Function, Physical Fitness, and Body Composition in Primary School Children: Impact of Socioeconomic Status

CONTEXT

Physical inactivity and sedentary behaviors are associated with adverse health outcomes in both adults and children. The purpose of this study was to investigate the effects of a 9-week program using a Cycle Desk during school time in French primary school children from high or low socioeconomic status (SES) on body composition, physical fitness (PF), and executive function.

METHODS

Seventy-five (n = 75) children completed a test battery before and after 9 weeks of use of Cycle Desk to evaluate anthropometric characteristics, body composition, PF, and executive function.

RESULTS

Body mass index increased significantly (P = .0095), while body fat decreased after the use of Cycle Desks (P < .0001). Specifically, lean mass increased in the high-SES group while it decreased in the low-SES group (P < .0001). After 9 weeks, there was an improvement in motor skills (P < .0001), upper and lower limbs' strength (P < .0001), and executive function performance (P < .0001). More specifically, the low-SES group had a greater improvement in motor skills and maximal aerobic speed between T0 and T1, compared to the high-SES group (P = .001, P = .023, respectively). In contrast, the high-SES group had a greater improvement in executive function at 9 weeks of use of Cycle Desk compared with the low-SES group (P = .0084).

CONCLUSIONS

The promotion of low-intensity physical activity with the use of a Cycle Desk at school may help offset some adverse effects of excess sedentary behavior among children. Moreover, this strategy appears to be particularly effective in children from low-SES backgrounds. What's New: The use of a Cycle Desk during school time has no deleterious effects on PF as well as cognitive executive functions in primary children. Modifications are more beneficial in children from low SES.

Prefrontal Cortex Corticotropin-Releasing Factor Receptor 1 Conveys Acute Stress-Induced Executive Dysfunction

BACKGROUND

The medial prefrontal cortex (mPFC) subserves complex cognition and is impaired by stress. Corticotropin-releasing factor (CRF), through CRF receptor 1 (CRFR1), constitutes a key element of the stress response. However, its contribution to the effects of stress in the mPFC remains unclear.

METHODS

Mice were exposed to acute social defeat stress and subsequently to either the temporal order memory (n = 11-12) or reversal learning (n = 9-11) behavioral test. Changes in mPFC Crhr1 messenger RNA levels were measured in acutely stressed mice (n = 12). Crhr1^loxP/loxP mice received either intra-mPFC adeno-associated virus-Cre or empty microinjections (n = 17-20) and then were submitted to acute stress and later to the behavioral tests. Co-immunoprecipitation was used to detect activation of the protein kinase A (PKA) signaling pathway in the mPFC of acutely stressed mice (n = 8) or intra-mPFC CRF injected mice (n = 7). Finally, mice received intra-mPFC CRF (n = 11) and/or Rp-isomer cyclic adenosine 3',5' monophosphorothioate (Rp-cAMPS) (n = 12) microinjections and underwent behavioral testing.

RESULTS

We report acute stress-induced effects on mPFC-mediated cognition, identify CRF-CRFR1-containing microcircuits within the mPFC, and demonstrate stress-induced changes in Crhr1 messenger RNA expression. Importantly, intra-mPFC CRFR1 deletion abolishes acute stress-induced executive dysfunction, whereas intra-mPFC CRF mimics acute stress-induced mPFC dysfunction. Acute stress and intra-mPFC CRF activate the PKA signaling pathway in the mPFC, leading to cyclic AMP response element binding protein phosphorylation in intra-mPFC CRFR1-expressing neurons. Finally, PKA blockade reverses the intra-mPFC CRF-induced executive dysfunction.

CONCLUSIONS

Taken together, these results unravel a molecular mechanism linking acute stress to executive dysfunction via CRFR1. This will aid in the development of novel therapeutic targets for stress-induced cognitive dysfunction.

[The stimulating impact of light on brain cognition function]

Light regulates multiple non-visual circadian, neuroendocrine, and neurobehavioral functions, and conveys a strong stimulating signal for alert-ness and cognition. This review summarizes a series of neuroimaging studies investigating the brain mechanisms underlying the latter stimulating impact of light. Results of these studies are compatible with a scenario where light would first hit subcortical areas involved in arousal regulation before affecting cortical areas involved in the ongoing non-visual cognitive process, and then cognitive performance. Recent data demonstrated that the non-visual impact of light is most likely triggered via outputs from intrinsically photosensitive retinal ganglion cells (ipRGC) expressing the photopigment melanopsin, which are maximally sensitive to blue light. In addition, the stimulating impact of light is intimately related to wakefulness regulation as it changes with circadian phase and sleep pressure. Finally, markers of inter-individual difference have also been described: age, PERIOD3 genotype, and psychiatric status. This review emphasizes the importance of light for human brain cognitive function and for cognition in general.