The Effects of Hypoxia on P300 and Reaction Time

Abstract : This experiment investigated the effects of three levels of arterial oxyhemoglobin saturation (SaO2 of 75%, 70% and 65%) on reaction time (RT) and p300 latency and amplitude. Ten subjects responded to visually presented male or female names in an oddball paradigm with accuracy controlled at a high level. Hypoxia increased both RT and p300 latency in a dose-related manner and these variables were strongly correlated. Hypoxia did not influence p300 amplitude. The increase in p300 latency is interpreted as further evidence that hypoxia slows stimulus evaluation processes and that, under the right circumstances, p300 could be used to index the effects of hypoxia on performance. Reaction time (RT) is the traditional measure for assessing the timing of cognitive stages of information processing but it is an end product and therefore includes the time to evaluate a stimulus, choose a response and organize it. It has recently been proposed that RT could be supplemented by p300 as a means for distinguishing between stages of processing (2,3). p300 is a positive going, endogenous, event related brain potential (ERP), occurring within the period 300 to 600 ms after the stimulus. (js)