Cognitive performance and event-related brain potentials under simulated high altitudes

Abstract

The effects of hypobaric hypoxia on cognitive processing in humans were studied by recording event-related potentials (ERPs) from the scalp in a go/no-go reaction time (RT) paradigm under various simulated high altitudes. Most subjects indicated abrupt impairment of RT at high altitudes. RTs lengthened in association with changes in latency and amplitude of the N2-P3 components, reflecting sensory discrimination and evaluation processes. Some subjects did not suffer any changes in RT up to an extremely high altitude of 6,000 m. In the latter case, although the N2-P3 components did not undergo any changes, the P3 component was followed by a sequence of negative on-going (frontal maximum) and positive on-going (parietal maximum) slow waves. The amplitudes of these slow waves increased as altitude increased. Although these same waves appeared in the ERPs of subjects who demonstrated the increase in RTs at high altitudes, when the subjects failed in the RT task, both of the slow waves either disappeared or diminished. Such slow waves may be associated with attempts to maintain RTs against the deteriorative effects of hypobaric hypoxia.

Electrophysiological correlates of cognition improve with nap during sleep deprivation

“…There was no signiWcant change in the N1, P2, and N2 components of P300. N1 and N2 components are related to sensory possessing of a stimulus (Kida and Imai 1993). N2 precedes P3 and may be directly aVected by the absolute timing of decision processes in sensory discrimination; and it is also sensitive to the cognitive attributes of the stimulus (Ritter et al 1979(Ritter et al , 1982.…”

Prolonged dry apnoea: effects on brain activity and physiological functions in breath-hold divers and non-divers

“…Thus, acute hypoxia affects cognitive processes (Kida and Imai 1993), inducing dysfunction of psychomotor performance, attention impairment, verbal fluency deficits, language production, cognitive fluency, and short-term memory (Virués-Ortega et al 2004). Acute hypercapnia in its turn leads to a wide range of negative consequences: lightheadedness and faintness, a mild anxiety (occasionally), sense of smothering, mild euphoria, and headache (Parsons et al 2001).…”

Human Auditory Steady-State Responses during Repeated Exposure to Hypobaric Hypoxia

“…Due to these many variables, it is not surprising that a significant correlation between SaO 2 and electrophysiological behaviour was observed only in some of our subjects. For the mild levels of hypoxia that can be safely reached in man, such a correlation was even lacking in several other studies [Mosko et al, 1981;Sohmer et al, 1982;Urbani and Lucertini, 1994], while an interindividual difference of auditory P300 behaviour under hypoxia was also observed by Kida and Imai [1993] in 38 subjects. However, when more severe levels of hypoxia can be reached, as in the animal model, the correlation between SaO 2 and AEP behaviour can be increased [Sohmer et al, 1989].…”

“…On the other hand, other data indicates only amplitude variations [Colin et al, 1978;Sohmer et al, 1982Sohmer et al, , 1989, that would rather suggest a decreased synchronism in neural discharge. Finally, in some papers, both latency and amplitude were affected by hypoxia [Kida and Imai, 1993;Sohmer et al, 1986a, b]. There are several factors that can contribute to such discrepancies.…”

“…3). The presence of big interindividual differences in these early moments of exposure could be related to the wide range of tolerance to hypoxia due to several factors such as age, environmental temperature, habit of smoking tobacco, or variable respiratory activity [Holmstrom, 1971;Kida and Imai, 1993]. Moreover, the interindividual variability of systems responsible for oxygen transport between blood and cells and across cell membranes must be considered, together with individual sensitivity to hypoxia on the part of biochemical systems involved in ATP supply and demand within the central nervous system, as those involved in glycolysis, transphosphorylation, Krebs cycle, cytosolic redox, etc.…”