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Contingent negative variation and evoked potential amplitude as a function of inspired nitrous oxide concentration

1979; Elsevier BV; Volume: 47; Issue: 4 Linguagem: Francês

10.1016/0013-4694(79)90163-9

1872-6380

P. B. C. Fenwick, J Bushman, Richard Howard, I.R. PERRY, T Gamble,

Neural dynamics and brain function

Nine subjects were given to breath 10%, 20%, 30% and 40% nitrous oxide in oxygen. The inhaled gas concentrations were monitored by a mass spectrograph. At each gas concentration the CNV was measured in a standard long S1–S2 CNV paradigm to a click and tone with a mandatory button press at S2. The results confirmed the previous observations of Lader and Morris (1974) that the cortical evoked potential decreases rapidly with increasing concentrations of nitrous oxide. The CNV, however, against prediction remains surprisingly well preserved up to the borders of unconsciousness. In this situation there is little correlation between CNV amplitude and attention, arousal or reaction time. Neuf sujets ont respiré un mélange d'O2 et de 10%, 20%, 30% ou 40% de N2O. Les concentrations de gaz inhalées étaient controlées par spectrographie de masse. Pour chaque concentration, on mesurait la VCN obtenue dans un paradigme standard S1 (clic)—S2 (son), avec consigne d'appui sur bouton à S2. Les résultats ont confirmé les observations antérieures (Lader and Morris, 1974), d'une décroissance rapide du potentiel évoqué cortical, lorsque croît la concentration de N2O. En revanche, et contre toute attente, la VCN est restée étonnamment constante, jusqu'aux limites de l'inconscience. Dans cette situation, il y a peu de corrélation donc entre l'amplitude de la VCN et l'attention, la vigilance ou le temps de réaction.