Mustafa Shirzad , James Van Riesen , Nikan Behboodpour , Matthew Heath
{"title":"10-min exposure to a 2.5% hypercapnic environment increases cerebral blood blow but does not impact executive function","authors":"Mustafa Shirzad , James Van Riesen , Nikan Behboodpour , Matthew Heath","doi":"10.1016/j.lssr.2023.07.003","DOIUrl":null,"url":null,"abstract":"<div><p>Space travel and exploration are associated with increased ambient CO<sub>2</sub><span> (i.e., a hypercapnic environment). Some work reported that the physiological changes (e.g., increased cerebral blood flow [CBF]) associated with a chronic hypercapnic environment contributes to a “space fog” that adversely impacts cognition and psychomotor performance, whereas other work reported no change or a positive change. Here, we employed the antisaccade task to evaluate whether transient exposure to a hypercapnic environment influences top-down executive function (EF). Antisaccades require a goal-directed eye movement mirror-symmetrical to a target and are an ideal tool for identifying subtle EF changes. Healthy young adults (aged 19–25 years) performed blocks of antisaccade trials prior to (i.e., pre-intervention), during (i.e., concurrent) and after (i.e., post-intervention) 10-min of breathing factional inspired CO</span><sub>2</sub> (FiCO<sub>2</sub>) of 2.5% (i.e., hypercapnic condition) and during a normocapnic (i.e., control) condition. In both conditions, CBF, ventilatory and cardiorespiratory responses were measured. Results showed that the hypercapnic condition increased CBF, ventilation and end-tidal CO<sub>2</sub> and thus demonstrated an expected physiological adaptation to increased FiCO<sub>2</sub>. Notably, however, null hypothesis <em>and</em> equivalence tests indicated that concurrent and post-intervention antisaccade reaction times were refractory to the hypercapnic environment; that is, transient exposure to a FiCO<sub>2</sub> of 2.5% did not produce a real-time or lingering influence on an oculomotor-based measure of EF. Accordingly, results provide a framework that – in part – establishes the FiCO<sub>2</sub> percentage and timeline by which high-level EF can be maintained. Future work will explore CBF and EF dynamics during chronic hypercapnic exposure as more direct proxy for the challenges of space flight and exploration.</p></div>","PeriodicalId":18029,"journal":{"name":"Life Sciences in Space Research","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Life Sciences in Space Research","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214552423000585","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Space travel and exploration are associated with increased ambient CO2 (i.e., a hypercapnic environment). Some work reported that the physiological changes (e.g., increased cerebral blood flow [CBF]) associated with a chronic hypercapnic environment contributes to a “space fog” that adversely impacts cognition and psychomotor performance, whereas other work reported no change or a positive change. Here, we employed the antisaccade task to evaluate whether transient exposure to a hypercapnic environment influences top-down executive function (EF). Antisaccades require a goal-directed eye movement mirror-symmetrical to a target and are an ideal tool for identifying subtle EF changes. Healthy young adults (aged 19–25 years) performed blocks of antisaccade trials prior to (i.e., pre-intervention), during (i.e., concurrent) and after (i.e., post-intervention) 10-min of breathing factional inspired CO2 (FiCO2) of 2.5% (i.e., hypercapnic condition) and during a normocapnic (i.e., control) condition. In both conditions, CBF, ventilatory and cardiorespiratory responses were measured. Results showed that the hypercapnic condition increased CBF, ventilation and end-tidal CO2 and thus demonstrated an expected physiological adaptation to increased FiCO2. Notably, however, null hypothesis and equivalence tests indicated that concurrent and post-intervention antisaccade reaction times were refractory to the hypercapnic environment; that is, transient exposure to a FiCO2 of 2.5% did not produce a real-time or lingering influence on an oculomotor-based measure of EF. Accordingly, results provide a framework that – in part – establishes the FiCO2 percentage and timeline by which high-level EF can be maintained. Future work will explore CBF and EF dynamics during chronic hypercapnic exposure as more direct proxy for the challenges of space flight and exploration.
期刊介绍:
Life Sciences in Space Research publishes high quality original research and review articles in areas previously covered by the Life Sciences section of COSPAR''s other society journal Advances in Space Research.
Life Sciences in Space Research features an editorial team of top scientists in the space radiation field and guarantees a fast turnaround time from submission to editorial decision.