Fig. 7.

(A) In a single subject (S4), we show PAC within the math-selective aIPS site (Far Left). The low-frequency band whose phase is most coupled to the HFB power at the same aIPS site is demarcated by the yellow dashed lines. The second and third images from the left show the coupling of aIPS phase to VTC HFB amplitude and of VTC phase to aIPS HFB amplitude. Note that the aIPS phase is most coupled to the HFB amplitude at sites within the pITG. The fourth image from the left shows the coupling of the phase at each VTC site to the HFB amplitude at the same site. The image on the right shows the magnitude of the HFB response at each VTC site during math trials relative to the ITI. Note that the sites with the most PAC during math trials are not necessarily the ones with the largest HFB response. (B) In the same subject, we show the response properties of the site showing the highest bottom-up PAC (pITG to aIPS) (Upper) and the site showing the highest top-down PAC (aIPS to pITG) (Lower). Note that the pITG site with the largest bottom-up coupling responded to the passive presentation of visual numerals (task 1) but did not show much response during active mathematical computation (task 2), whereas the site showing the strongest top-down PAC from the IPS was slightly more anterior and did not show a strong response to the passive presentation of visual numerals but showed selective activity during active mathematical computation. (C, Left) Average PAC between aIPS_math and three different regions within the VTC averaged across the five subjects with simultaneous aIPS_math and pITG_math coverage. (Right) Average within-site PAC in each of three different regions within the VTC averaged across the same five subjects. Error bars indicate SE across electrode pairs (left) or across electrodes (right). Significant differences in PAC are denoted by solid brackets (P < 0.05, FDR corrected) and dashed brackets (P < 0.05, uncorrected).