Fig 1.
(A) Schematic of the body and the cued body parts (colors) are shown. (B) The layout of the whole body graph is presented with the colored nodes representing the body parts. The position of nodes in the graph is arbitrary and chosen to resemble the physical position of the body parts. The lines denote which body parts are ‘connected’ on the basis the cortical homunculus ordering of body parts. (C) Schematic of the graph theory metrics: connectivity (red), clustering coefficient (blue), and betweenness centrality (black) that relies on path length (green). Example modules consisting of multiple body part nodes are denoted by the black dashed lines. These graph theory metrics were applied to all body parts in all ROIs. The lines denote existing connections between body part nodes that were determined by correlations of the mean body part pRFs and thresholding. The nodes in the graph have the same order as in (B).
Table 1.
The table describes the movements that were made for each body part condition.
Subjects viewed a single forward movement cue and a single backward movement cue per event. Rightmost column indicates in which of the two runs a body part cue was presented.
Fig 2.
For each included cortical area, the surface area as estimated by Freesurfer is shown per body part representation. The surface area is normalized to the total surface area of each cortical area. Body part representations are determined on the basis of the pRF center value.
Fig 3.
The pRF centers are shown on an average subject pial surface (left) and inflated surface (right) from a lateral point of view (top) and medial point of view (bottom). Colors indicate the body part that was estimated as the pRF center. The ROIs are denoted by the lines drawn on the surfaces: primary motor cortex (M1), primary somatosensory cortex (S1), supplementary motor area (SMA), dorsal premotor cortex (PMd), ventral premotor cortex (PMv), Insula/Sylvian fissure (Insula), inferior parietal cortex (iPC), and superior parietal cortex (sPC).
Fig 4.
The pRF size is shown on an average subject pial surface (left) and inflated surface (right) from a lateral point of view (top) and medial point of view (bottom). Colors indicate the pRF size. The ROIs are denoted by the lines drawn on the surfaces: primary motor cortex (M1), primary somatosensory cortex (S1), supplementary motor area (SMA), dorsal premotor cortex (PMd), ventral premotor cortex (PMv), Insula/Sylvian fissure (Insula), inferior parietal cortex (iPC), and superior parietal cortex (sPC).
Fig 5.
pRF size and cortical coordinates per pRF center.
For each ROI the mean cortical coordinates (red circles) and mean pRF size (blue squares) are plotted versus the estimated pRF centers (horizontal axis). Both the depicted coordinates and pRF size values were calculated as the mean value across neuronal populations with the same pRF center (horizontal axis). Error bars denote the S.E.M. across subjects.
Fig 6.
For each ROI (columns), the complete response field was normalized and averaged over all vertices sharing the same pRF centers (rows), creating the mean body part pRF (i.e. 18 body part positions per pRF center and ROI). The bars denote the proximity of body parts to the center of the response field. The higher the bar, the closer the corresponding body part is to the response field’s center. For each mean body part pRF, the body part equal to the pRF center is depicted by the orange bar, and is by definition closest to the response field center. The Error bars denote the S.E.M. across subjects.
Fig 7.
Whole-body-graphs are presented per ROI (from left to right) and for the connectivity, clustering and betweenness centrality coefficients (from top to bottom). The colors of each node in the graphs correspond to a specific body part given by the schematic at the far right. The connections between any 2 body part nodes was calculated per ROI and shown here through the lines connecting the nodes. The thicker the line the stronger the connection between body parts. (A) Connectivity values per body part node and ROI are depicted. The size of the body part nodes presents the size of the connectivity value per node. (B) Clustering coefficients have the same layout and graphs as the connectivity values. Here the size of the body part node reflects the strength of the clustering coefficient. (C) The size of the body part nodes in the ROI graphs reflects the strength of the betweenness centrality coefficient.
Fig 8.
For each ROI, different modules are represented by different colors. Note that the colors only define a cluster of nodes within one graph, and any correspondence of colors between graphs is purely accidental. The whole-body graph layout is presented at the outmost right indicating the node-body part relationship.
Fig 9.
Top row shows the images presented throughout the task for the hand/arm/torso run (left) and face/leg-run (right). Middle and bottom rows show examples of the flexion-extension cues for the elbow (left) and knee (right).
Fig 10.
The schematic shows the different steps in the fitting procedure. The different body parts are fitted in one half of a static Gaussian response field model (non-rigid pRF model), which is multiplied by the motor task onset design matrix (Motor task). The multiplication generates the estimated pRF response amplitude for each condition in time (pRF response), which is convolved with a canonical hemodynamic response function (HRF). This results in predicted timeseries (Prediction), which is contrasted with the observed fMRI timeseries (Data). Using the LMA, the position of the body parts in the non-rigid pRF model is updated in order to obtain the best fit.
Fig 11.
The non-rigid pRF fit (black line) with the timeseries of 2 surface vertices (colored dashed lines) are shown for 1 participant (#6) in the upper and lower panels. Movement cues over time are presented at the horizontal axis. On the right, the fit of body parts within the static Gaussian response field is shown, used to construct the timeseries fit. The FWHM/2 within the static Gaussian response field is depicted by the black dashed line. The pRF size is determined on the number and spread of fitted body parts (mentioned on the horizontal axis) within the FWHM/2.