Abstract

Attention disorder in schizophrenia is described as an impairment of the ability to ignore irrelevant stimuli and to attend selectively to relevant stimuli, This study was carried out to examine the attention disorder in animals, Rats were injected with L-dopa, the Dopamine agonist, and then, the effect of L-dopa on their attention was investigated, In the first stage, rats were trained to learn one stimulus was irrelevant to the environment by a method of "Learned Irrelevancy", In the second stage, they were conditioned to a compound stimulus consisting of the irrelevant stimulus used in the first stage and new novel neutral stimulus, The level of attention to each stimulus was inferred from the level of conditioning, The effect of L-dopa was limited to each of the two stages to determine whether the attention disorder was owing to the effect of L-dopa on the first stage or on the second stage, The results showed that the administration of L-dopa influenced the process of second stage and the attention disorder occured as a consequence of the impairment of ignoring the irrelevant stimulus.