the effects of pharmacologic perturbations of fef activity on target selection and the visual responses of v4 neurons was studied in three macaque monkeys performing fixation and eye movement tasks ( supplementary information ) . all experimental procedures were in accordance with national institutes of health guide for the care and use of laboratory animals , the society for neuroscience guidelines and policies , and approved by the stanford university animal care and use committee . eye position was monitored with a scleral search coil . in each experiment , we infused small volumes of drug into sites within the fef through a surgically implanted titanium chamber overlaying the arcuate sulcus using a custom - made recording microinjectrode . we identified fef sites by eliciting short - latency , fixed - vector saccadic eye movements with trains ( 50  100 ms ) of biphasic current pulses ( 50 a ; 250 hz ; 0.25 ms duration ) . in the same experiment response fields ( rf ) of v4 neurons were all located in the lower quadrant of the contralateral hemifield ( < 12 eccentricity ) . the position of the fef microinjectrode was adjusted so that the saccade elicited by fef microstimulation either shifted the monkey s gaze to within the v4 rf ( overlapping ) or far outside of it ( non - overlapping ) .
the prefrontal cortex ( pfc ) is thought to modulate sensory signals in posterior cortices during top - down attention1,2 , yet little is known about the underlying neural circuitry . 
 experimental and clinical evidence suggest that prefrontal dopamine plays an important role in cognitive functions3 , acting predominantly through d1 receptors ( d1rs ) . here 
 we show that dopamine d1rs mediate prefrontal control of signals within visual cortex . 
 we pharmacologically altered d1r - mediated activity within the frontal eye field ( fef ) of the pfc and measured its effects on the responses of neurons within visual cortex . 
 this manipulation was sufficient to enhance the response magnitude , orientation selectivity and response reliability of neurons in area v4 to an extent comparable with the known effects of top - down attention . 
 the observed enhancement in v4 signals was restricted to neurons with response fields ( rfs ) overlapping the part of visual space affected by the d1r manipulation . altering d1r or d2r - mediated fef activity increased saccadic target selection , but the d2r manipulation did not enhance v4 signals . 
 our results identify a role of d1rs in mediating the control of visual cortical signals by the pfc and demonstrate how processing within sensory areas can be altered in mental disorders involving prefrontal dopamine .