A Method of Assessment of Central Nervous Function in Mice with Viral Encephalomyelitis

A quantitative investigation into the balancing and locomotor function, learning and memory of mice infected with an arthropod-borne virus is described. Mice can remain on a rod rotating in a horizontal plane about its long axis, and this natural ability can be assessed by counting the number of times they fall off. The mice improve their ability with experience and can retain the improved ability for short periods. Natural ability in mice about 25 days old was greater than in those 3 weeks older. This ability was diminished by the encephalomyelitis which resulted from infection with Langat virus. Within the limits of the experiments the rate of learning depended upon the number of trials rather than the interval between them. Memory lasting 10 days or longer was demonstrated in some mice but evidence on the effect of ageing on learning and memory was conflicting. Despite the presence of Langat virus infection the learning ability and memory of mice which showed no clinical signs of disease appeared to be unimpaired. 129