Biology subjects

Radel, R.

Publications and source records attributed to Radel, R..

4 recordsLinked to original sources

bioRxiv2019

Testing the role of cognitive inhibition in physical endurance using high-definition transcranial direct current stimulation over the prefrontal cortex.

The aim of this study was to clarify the role of the prefrontal cortex (PFC) in physical effort regulation. We hypothesized that the PFC would be progressively involved in physical endurance through the engagement of cognitive inhibition, which would be necessary to maintain effort by inhibiting fatigue-related cues. This hypothesis was examined using a double-blind, sham-controlled, within-subjects study (N = 20) using high-definition (HD) transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (dlPFC). Participants had to maintain a knee extensor contraction at 30% of their maximal force while simultaneously performing an Eriksen flanker task to evaluate their inhibition performance during the task. Anodal stimulation of the dlPFC influenced response to the cognitive task during exercise, as seen by slower response times and better accuracy. However, it did not lead to any measureable improvement in cognitive inhibition and did not influence endurance time. There was no correlation between cognitive inhibition and the maintenance of physical effort. This result could be explained by some methodological limitations of our protocol, and we also provide alternative explanations for the contribution of the PFC in physical endurance.

neuroscience↗

bioRxiv2018

Impact of Physical and Cognitive Exertion on Cognitive Control

In a recent study, the differential effects of prolonged physiologically challenging 4 exercise upon two executive processes (cognitive control and working memory) have been 5 investigated. However, the impact of exercise on the selective inhibition task remained debatable and needed further analysis to dissociate the effects induced by exercise intensity from those induced by the time spent on task upon cognitive control outcomes. In this study we propose a thorough analysis of these data, using a generalized mixed model on a trial-by-9 trial basis and a new measure of the strength of the automatic response based on reaction time distribution, to disentangle the effect of physical fatigue from cognitive fatigue. Despite the prolonged duration of exercise, no decline in cognitive performance was found in response to physical fatigue. The only change observed over the 60-min exercise was an acceleration of the correct trials and an increase of errors for incompatible trials. This pattern, similar in both exercise conditions, supports the occurrence of cognitive fatigue induced by the repetition of the cognitive tasks over time.

neuroscience↗

bioRxiv2018

Avoiding sedentary behaviors requires more cortical resources than avoiding physical activity: An EEG study

HighlightsO_LIIndividuals are slower at approaching sedentary than physical activity stimuli\nC_LIO_LIIndividuals are quicker at avoiding sedentary than physical activity stimuli\nC_LIO_LIThese effects are particularly pronounced in physically active individuals\nC_LIO_LIAvoiding sedentary behaviors is associated with high levels of conflict monitoring and inhibition\nC_LIO_LIAdditional brain resources are required to escape a general attraction toward sedentary behaviors\nC_LI\n\nAbstractWhy do individuals fail to exercise regularly despite knowledge of the risks associated with physical inactivity? Automatic processes regulating exercise behaviors may partly explain this paradox. Yet, these processes have only been investigated with behavioral paradigms based on reaction times. Here, using electroencephalography, we investigated the cortical activity underlying automatic approach and avoidance tendencies toward stimuli depicting physical activity and sedentary behaviors in 29 young adults who were physically active (n=14) or physically inactive but with the intention of becoming physically active (n=15). Behavioral results showed faster reactions when approaching physical activity compared to sedentary behaviors and when avoiding sedentary behaviors compared to physical activity. These faster reactions were more pronounced in physically active individuals and were associated with changes during sensory integration (earlier onset latency and larger positive deflection of the stimulus-locked lateralized readiness potentials) but not during motor preparation (no effect on the response-locked lateralized readiness potentials). Faster reactions when avoiding sedentary behaviors compared to physical activity were also associated with higher conflict monitoring (larger early and late N1 event-related potentials) and higher inhibition (larger N2 event-related potentials), irrespective of the usual level of physical activity. These results suggest that additional cortical resources were required to counteract an attraction to sedentary behaviors. Data and Materials [https://doi.org/10.5281/zenodo.1169140].

neuroscience↗

bioRxiv2017

Reward and automatic processes in exercise behavior: A new approach and a systematic review

BackgroundIn a time of physical inactivity pandemic, attempts to better understand the factors underlying the regulation of exercise behavior is important. The dominant neuropsychological approach to exercise behavior explains physical activity as a reward. However, the opposite of physical exertion -- behaviors minimizing energy cost -- may also be a reward, which activates automatic reactions favoring the engagement in behaviors associated with lower energetic costs.\n\nObjectiveOur objective was to systematically review studies testing the automatic reactions triggered by stimuli associated with different types of exercise behavior (e.g., physical activity, sedentary behaviors) and energetic cost variations (e.g., behaviors minimizing energetic cost).\n\nMethodsTwo authors systematically searched, screened, extracted, and analyzed data from articles in the MEDLINE database.\n\nResultsWe included 26 studies. Three types of automatic processes were tested: Affective reactions, attentional capture, and approach tendencies. Results show that automatic reactions toward stimuli depicting exercise behaviors explained individuals level of physical activity. Brain imaging results show that stimuli associated with exercise behavior activate regions associated with reward, but these studies were scarce.\n\nConclusionReward is an important factor of exercise behavior. There is strong evidence showing that physical activity is a reward. While brain imaging results suggest that sedentary behaviors are also a reward, behaviors minimizing energetic cost have not been investigated so far. Additional studies are required to establish a strong and complete framework of reward in exercise behavior.\n\nKey points- Behavioral and brain imaging studies using different types of automatic behavior show that physical activity is a reward\n- Behaviors minimizing energetic cost have been essential to evolutionary survival and are likely to be a reward. However, experimental evidence remains scarce\n- The dominant neuropsychological approaches to exercise behavior may be incomplete, which may partly explain our current inability to counteract the pandemic of physical inactivity

neuroscience↗