title: A comparison of visual and auditory reaction time and P300 latency thresholds to acute hypoxia.
abstract: To investigate the influence of stimulus modality on the slowing produced by hypoxia, thresholds were estimated using reaction time (RT) and the event-related brain potential P300. Six trained subjects responded to oddball light flashes or tone pips while breathing low-oxygen mixtures that were manipulated to produce arterial blood oxygen saturations (SaO2) ranging from 77-86%. Both RT and P300 were slowed in a dose-dependent manner. The threshold for slowing was independent of stimulus modality for both measures, and estimated to be in the range 81-82% SaO2. P300 amplitude dissociated from the response time measures by exhibiting an inverted-U dose-response function. We draw three conclusions from these results: a) the failure to observe a higher visual threshold for the response time measures is inconsistent with the traditional belief that audition is relatively insensitive to hypoxia; b) the equal sensitivity of P300 latency and RT to hypoxia implicates stimulus evaluation processes in slowing; and c) P300 amplitude may reflect the activity of physiological compensatory mechanisms to hypoxia.
authors.affiliation: Graduate Programme in Exercise and Health Science, York University, Downsview, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Fowler
authors.forename: H
authors.initials: H
authors.lastname: Prlic
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001307:Auditory Perception; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D008297:Male; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D011930:Reaction Time / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology*; D014796:Visual Perception
chemical_list: D010100:Oxygen