Theta connectivity during prioritization is directed from the lateral prefrontal cortex to the posterior parietal cortex. A, Participants performed the retro-cue WM task and benefited from the retro-cue in response time, but not accuracy. The red lines depict participants who did not benefit from the retro-cue relative to the neutral-cue. **p < 0.01. Error bars are SEM. One participant with an average response time of 3.62 s is not pictured and did not show a retro-cue benefit. B, For those that demonstrated a retro-cue benefit in response time or accuracy, electrodes were implanted in both the frontal and parietal cortices in seven participants. Frontal electrodes are indicated in orange and parietal in blue. A, anterior; P, posterior; L, left; R, right. C, Time-frequency analysis revealed a similar pattern of activity for intracranial EEG as with EEG. Theta oscillations were increased in the lateral prefrontal cortex (orange rectangle) and posterior parietal cortex (blue rectangle) for retro-cues versus neutral-cues, but alpha oscillations were not. Nonetheless, there was a quantitative increase in alpha oscillations and a reduction in high gamma activity contralateral to irrelevant information in LO. Ipsi, ipsilateral; contra, contralateral. D, Effective connectivity in the theta-frequency band, PSI, was increased from the left lateral prefrontal to the left posterior parietal cortex for retro-cues relative to neutral-cues (highlighted in blue), but did not increase for other regions in the parietal cortex. PFC, prefrontal cortex; MFG, middle frontal gyrus; sPCS, superior precentral sulcus; SPL, superior parietal lobule; IPS, intraparietal sulcus; S1, primary somatosensory cortex; post-CS, postcentral sulcus; TPJ, temporoparietal junction; LO, lateral occipital. Error bars are a 95% confidence interval. ***p < 0.001; **p < 0.01; *p < 0.05; n.s. = not significant.