Lesional effects of primary cosmic heavy ions on rat brain

Heavy ions were detected with nuclear emulsions plates fixed on the skulls of 20 rats which were exposed to cosmic rays at an altitude of 32,000 metres. Eight cases are described of correlations between ions tracks and brain lesions. The passage of heavy ions seems to cause functional rather than destructive alterations in the cells. The metabolic disturbances give a dark aspect to the neurons. The lesions generally appear in wide areas around the track and this fact suggests a physiopathological phenomenon of amplification. An evaluation of this biological hazard during flights of long duration at high altitude will be possible when the mechanism of action of heavy ions on nervous tissue is better known, and particularly if experiments carried out in accelerators confirm the small number of results obtained in flight.