Attention enhances gamma frequency synchronization between prefrontal and visual cortex areas during tasks requiring focused attention. This synchronization is initiated by the frontal eye field (FEF) and involves a time delay of 8-13 ms, which may optimize communication between areas. Electrical recordings in monkeys and humans show that attention increases neural synchrony in ventral stream areas, particularly in gamma frequencies. This synchronization is likely driven by top-down attentional feedback from prefrontal cortex to visual cortex, enhancing firing rates and improving the processing of relevant stimuli. The study used paired recordings in FEF and area V4 to show that attention to a stimulus in their shared receptive field enhances oscillatory coupling between the two areas, particularly at gamma frequencies. This coupling is time-shifted, suggesting that FEF initiates the synchronization, which is then transmitted to V4. The time delay may allow for optimal spike timing, enhancing communication between areas. Granger causality analysis revealed that FEF has a significant causal influence on V4, and vice versa, with attentional effects appearing earlier in the FEF to V4 direction. This suggests that FEF initiates the gamma oscillations in V4, which are then transmitted back to FEF. The synchronization is enhanced by the overlap of receptive fields and is reduced when there is no overlap. The study also found that attention increases gamma coherence between LFPs recorded in FEF and V4, indicating that the synchronization is not solely due to common inputs but may involve coordinated activity between the areas. The time delay of 8-13 ms is consistent with conduction and synaptic delays, suggesting that this delay is optimal for spike timing and communication. The results suggest that FEF is a major source of attentional effects on gamma synchrony in V4 and other ventral stream areas. The synchronization may enhance spike timing-dependent plasticity, supporting learning and attentional processes. However, the effects are reduced when stimuli are not in the receptive fields of the areas, indicating that the synchronization is task-dependent and requires overlapping receptive fields. Overall, the study highlights the role of prefrontal and visual cortex in attentional processes, showing that synchronized oscillations at gamma frequencies are crucial for effective communication and processing of relevant stimuli. The findings suggest that attention enhances neural communication through coordinated oscillations, which are optimized by the timing and synchronization of activity between areas.Attention enhances gamma frequency synchronization between prefrontal and visual cortex areas during tasks requiring focused attention. This synchronization is initiated by the frontal eye field (FEF) and involves a time delay of 8-13 ms, which may optimize communication between areas. Electrical recordings in monkeys and humans show that attention increases neural synchrony in ventral stream areas, particularly in gamma frequencies. This synchronization is likely driven by top-down attentional feedback from prefrontal cortex to visual cortex, enhancing firing rates and improving the processing of relevant stimuli. The study used paired recordings in FEF and area V4 to show that attention to a stimulus in their shared receptive field enhances oscillatory coupling between the two areas, particularly at gamma frequencies. This coupling is time-shifted, suggesting that FEF initiates the synchronization, which is then transmitted to V4. The time delay may allow for optimal spike timing, enhancing communication between areas. Granger causality analysis revealed that FEF has a significant causal influence on V4, and vice versa, with attentional effects appearing earlier in the FEF to V4 direction. This suggests that FEF initiates the gamma oscillations in V4, which are then transmitted back to FEF. The synchronization is enhanced by the overlap of receptive fields and is reduced when there is no overlap. The study also found that attention increases gamma coherence between LFPs recorded in FEF and V4, indicating that the synchronization is not solely due to common inputs but may involve coordinated activity between the areas. The time delay of 8-13 ms is consistent with conduction and synaptic delays, suggesting that this delay is optimal for spike timing and communication. The results suggest that FEF is a major source of attentional effects on gamma synchrony in V4 and other ventral stream areas. The synchronization may enhance spike timing-dependent plasticity, supporting learning and attentional processes. However, the effects are reduced when stimuli are not in the receptive fields of the areas, indicating that the synchronization is task-dependent and requires overlapping receptive fields. Overall, the study highlights the role of prefrontal and visual cortex in attentional processes, showing that synchronized oscillations at gamma frequencies are crucial for effective communication and processing of relevant stimuli. The findings suggest that attention enhances neural communication through coordinated oscillations, which are optimized by the timing and synchronization of activity between areas.