Effects of different types of anoxia on the spontaneous and induced cerebral electrographic activity in the cat
Naquet, R.; Fernandez-Guardiola, A.
Journal de Physiologie 52: 885-902
1960
ISSN/ISBN: 0021-7948 PMID: 13727765 Document Number: 8804
In the present, study, changes of cerebral electrographic spontaneous or evoked activity during various types of anoxia (clamping of aorta, nitrogen inhalation and asphyxia) are analysed in the cat. After a description of the experimental techniques used, the authors studied the phases of installation and recuperation in cerebral anoxia of short duration. They described various stages of anoxia in which the variations of electrographic activity of the neo-cortex and bulbar reticular formation are compared to variations in blood pressure and pupillary diameter. These stages of anoxia being clearly defined, changes are studied in activity evoked by repetitive stimulation or by a single shock, not only applied to the sperific pathways (visual and auditive), but to the non-sperific stimulation of the non-specific nuclei of the thalamus. These results show: 1. The existence of a true phenomenon of cortico-reticular cerebral activation during the first stages of anoxia; when the anoxia progresses, an important "exeilation" of the mesencephalic and bulbar formations appears, and during this time the cortex shows signs of disturbance and is no longer capable of being activated; 2. The greater resistance to anoxia of the paucisynaptic afferent pathways reaching the cortex, than the resistance of the non-specifie multisynaplic reticular or thalamo-cortical pathways. Those two groups of results show that at the level of the cortex, as at the level of the bulbar reticular formation, anoxia does not act as a whole but that some elements are more sensitive than other.
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