The role of dopamine in maintenance and distractability of attention in the "prefrontal cortex" of pigeons.

Selective attention is a crucial component of all sensory processing. Here we test the role of dopamine in attentional selection and in the maintenance of attention. Pigeons were trained on a moving-dot paradigm comparable to the shell game. In this paradigm, pigeons had to select a target among distractors and maintain attention to the target. Target and distractors consisted of white dots, moving at random on a touch-screen. In this task, the demand on attention was modulated by varying the number of distractors and the duration of motion. Both manipulations affected performance equally. In the next step, we investigated the contribution of dopamine to attention. Intracranial injections of D1-antagonist (Sch23390) before testing led to decrements in performance that equally affected trials with different attentional demand. This drop in performance cannot be attributed to altered motivation or motor performance. We conclude that dopamine has a critical role in attention. It is involved in the selection of targets for attention and in the stabilization of attention against interference. This is comparable to the role dopamine plays in working memory and argues for similar mechanisms underlying selective attention and working memory.