Control of visual cortical signals by prefrontal dopamine

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Abstract
The prefrontal cortex has an important role in higher cognitive functions, and is thought to control the information in the visual cortex, but little is known about the specifics of this modulation. Behrad Noudoost and Tirin Moore now show that pharmacological modification of D1 dopamine receptors in the frontal eye field selectively affects responses of neurons in area V4 of the visual cortex and behaviourally increases target selection in that region. These results identify a role for D1 receptors in mediating the sensory areas in the frontal cortex and suggest how processing in sensory areas could be altered in mental disorders that involve prefrontal dopamine. The prefrontal cortex is thought to modulate sensory signals in posterior cortices during top-down attention1,2, but little is known about the underlying neural circuitry. Experimental and clinical evidence indicate that prefrontal dopamine has an important role in cognitive functions3, acting predominantly through D1 receptors. Here we show that dopamine D1 receptors mediate prefrontal control of signals in the visual cortex of macaques (Macaca mulatta). We pharmacologically altered D1-receptor-mediated activity in the frontal eye field of the prefrontal cortex and measured the effect on the responses of neurons in area V4 of the visual cortex. This manipulation was sufficient to enhance the magnitude, the orientation selectivity and the reliability of V4 visual responses to an extent comparable with the known effects of top-down attention. The enhancement of V4 signals was restricted to neurons with response fields overlapping the part of visual space affected by the D1 receptor manipulation. Altering either D1- or D2-receptor-mediated frontal eye field activity increased saccadic target selection but the D2 receptor manipulation did not enhance V4 signals. Our results identify a role for D1 receptors in mediating the control of visual cortical signals by the prefrontal cortex and suggest how processing in sensory areas could be altered in mental disorders involving prefrontal dopamine.