Aaron Gruber, Peter Dayan, Boris Gutkin, Sara Solla
Dopamine exerts two classes of effect on the sustained neural activity in prefrontal cortex that underlies working memory. Direct release in the cortex increases the contrast of prefrontal neurons, enhancing the ro- bustness of storage. Release of dopamine in the striatum is associated with salient stimuli and makes medium spiny neurons bistable; this mod- ulation of the output of spiny neurons affects prefrontal cortex so as to indirectly gate access to working memory and additionally damp sensi- tivity to noise. Existing models have treated dopamine in one or other structure, or have addressed basal ganglia gating of working memory ex- clusive of dopamine effects. In this paper we combine these mechanisms and explore their joint effect. We model a memory-guided saccade task to illustrate how dopamine’s actions lead to working memory that is se- lective for salient input and has increased robustness to distraction.