Figure 4.

Modulation of functional connectivity for the interaction between task and action type. (a) ROI‐based functional connectivity interaction analysis between task (task‐based functional connectivity, fixation baseline functional connectivity) and action type (tool use, tool transport) using independently defined seed regions. We quantified the degree to which functional connectivity was differentially driven by tool use planning and pantomiming epochs (hot colors) relative to tool transport planning and pantomiming epochs (cold colors) over and above changes in functional connectivity observed during baseline fixation events. We report significant effects if the two‐way modulation in functional connectivity satisfied three constraints: (i) functional connectivity must be significant bi‐directionally (e.g., when using region A as a seed and region B as a mask, and vice versa), (ii) at an alpha level of at least p < 0.01, and (iii) the effect size for the two‐way interaction must be moderate in magnitude (Hedges' G of 0.40 or higher). Functional connectivity that was bi‐directionally present but that did not survive p‐value correction (i.e., p < 0.05, uncorrected) is marked with a “/”; functional connectivity that was not significant is marked with an “X.” For tool use epochs, there was increased functional connectivity between the left SMG and left ventral anterior temporal lobe, and between the left SMG and left frontal operculum/inferior frontal gyrus. For tool transport epochs, we found increased functional connectivity between the left SMG and right collateral sulcus, left SMG and bilateral medial fusiform gyri, left SMG and left middle occipital gyrus, and between the left posterior middle temporal gyrus and left middle occipital gyrus. (b) the average Fisher‐transformed correlation coefficients associated with the two‐way interaction are plotted; error bars reflect standard error of the mean across participants. (c) the whole‐brain two‐way interaction map for the left SMG seed from Gallivan et al. (2013) illustrates modulations associated with tool use and tool transport events, which are qualitatively similar to what was observed using the BOLD contrast‐defined left SMG (see Supporting Information Figure S2 for whole‐brain functional connectivity interaction map). All voxels survive cluster correction using AlphaSim (minimum cluster size of 125 voxels, with an initial alpha value of p < 0.05). Abbreviations. ATL, left anterior temporal lobe; IFG, left frontal operculum/left inferior frontal gyrus; LCS, left collateral sulcus; LMFG, left medial fusiform gyrus; LMOG, left middle occipital gyrus; pIPS, left posterior intraparietal sulcus; PMv, left ventral premotor cortex; pMTG, left posterior middle temporal gyrus; RCS, right collateral sulcus; RMFG, right medial fusiform gyrus; SMG, left supramarginal gyrus