Hypoxia impairs brain prefrontal lateralization related to visuospatial orienting of attention as reflected by an ERPs CNV neuromarker

Aims: Brain oxygen requirements are among the highest of all biological organs, thus brain sensitivity to hypoxia is heavy. Indeed, much knowledge is available about the consequences of severe and near-lethal hypoxia on brain anatomy and physiology. By contrast, the impact of non-pathological hypoxia on neurocognitive processing and behaviors still remains relatively unexplored and controversial. The present study assessed alterations of brain functionality during a demanding yet structurally-not-hurtful hypoxia focusing on brain hemispheric processing specificity in alerting and spatial orienting of visual attention as reflected by an event-related contingent negative variation (CNV) neuromarker. Materials and Methods: We recorded high spatial-density ERPs in two separate sessions in which healthy volunteers breathed either ambient-air or oxygen-impoverished (~12.5%) air. During each session, three cue-target tasks eliciting either a phasic or a tonic alerting as well as a visuospatial orienting of attention were presented. Results: Prior targets presentation ERP waveforms showed a CNV with a maximum at prefrontal sites as indicated by topographical maps. In normoxia this variation was larger over the left as compared to the right hemisphere for orienting of attention but not for both phasic and tonic alerting. Most importantly, overall hypoxia boosted CNV but disrupted the orienting-related functional lateralization observed in normoxia. Discussion and Conclusions: Besides pointing at the CNV as a robust neuromarker of prefrontal processing lateralization associated with spatial orienting of visual attention, our findings indicate that a demanding yet not-hurtful hypoxia impairs this attention orienting-related lateralization. This hints at possible affinities with pathological alterations underpinning attentional deficits in specific neuropsychological patients.