The relationship between thiamine deficiency and performance of a learningtask in rats

We have been investigating the relationship between learning and thiamine. Electrical stimulation of mesencephalic periaqueductal gray matter (PAG) is known to have an aversive effect and elicits spontaneous instrumental esca pe behavior. We taught rats to press a lever to escape from the pain of ele ctrical stimulation by learning to rum a switch off. Then we examined the r elationship between learning and the thiamine concentration in various port ions of the brain. (1) One group of rats was given a normal diet and another group was given a thiamine-deficient diet which contained half of the amount of thiamine pre sent in the normal diet. We measured the response time required for each ra t to react by moving after an electrical impulse was applied, and the runni ng time during which the rat was moving from the starting point to the end point to press a lever. The rats that were fed the thiamine-deficient diet showed a slower response time and a longer running time than the rats fed t he normal diet. (2) We divided the rats fed the normal diet into two groups, one group trai ned to switch off a lever and the other group not trained for such a task. We found that the thiamine concentration in the blood of the rats in the tr ained group was significantly higher than that in the group without trainin g.