ANOXIC DEPRESSION OF LIGHT-EVOKED POTENTIALS IN RETINA AND OPTIC TECTUM OF CRUCIAN CARP

The crucian carp is an exceptionally anoxia-tolerant vertebrate. For t he brain, with its very high rate of ATP use, depression of energy use is likely to be an important strategy for anoxic survival. This study shows that the light-evoked response of the retina and the correspond ing evoked potential in optic tectum decrease in amplitude by 69 and 7 5%, respectively, during 38 min of anoxia, and by about 90% after 1 h in anoxia. Both responses were restored upon reoxygenation. The length of light exposure (5 s or 100 ms) did not affect the degree of anoxic depression. These results are the first to shaw an anoxia-induced dep ression of central nervous system (CNS) activity in vivo in this speci es, and indicate that the crucian carp temporarily turns off its visua l sense in order to reduce neural energy use during anoxic condition. (C) 1997 Elsevier Science Ireland Ltd.