ELECTRONIC SUPPLEMENTARY MATERIAL
Klein E, Suchan J, Moeller K, Karnath H-O, Knops A, Wood G, Nuerk, H-C, Willmes K.
Differential connectivity for magnitude processing and arithmetic facts in the fronto-parietal
network of numerical cognition. Brain Structure and Function.
Corresponding author:
Dr. Dr. Elise Klein (MD, PhD)
Knowledge Media Research Center
Neurocognition Lab
Schleichstr. 6
72076 Tuebingen
Germany
e.klein@iwm-kmrc.de
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Connectivity analysis
Number bisection task
Fig S1 Number bisection task: magnitude-related processing
Panel A reflects cortical regions showing an increase of fMRI signal due to increasing values
of the conjunction of increasing distance to the arithmetic middle, presence of decade
crossings and non-multiplicative triplets (FWE cluster-threshold corrected p < .05, cluster
size k = 15 voxels). Activated areas for magnitude-related processing include the IPS, pIPS,
IFG (BA 44, BA 45, and BA 47), SMA, FEF, the visual number form (VNF), and basal
ganglia, most of them bilaterally. Panel B depicts identified pathways in a 3D volume
rendering with PIBI values > 0.0148. It can be seen that for number magnitude-related
number bisection a system of both dorsal and ventral connections is recruited encompassing
the SLF system and the EC/EmC system, respectively (depicted in red). Panel C gives a
detailed view on the course of the respective fiber tracts in axial, sagittal and coronal
orientation.
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Fig S2 Number bisection task: Results for fact retrieval-related processing
Panel A depicts cortical regions associated with an increase of fMRI signal due to increasing
values of the conjunction of decreasing distance to the arithmetic middle, no decade
crossings, and multiplicative triplets. Activated areas for fact-retrieval related processing
included the left AG only at an FWE cluster-threshold corrected p < .05 (k = 15 voxels).
Additional activation was again identified in the SMG, MTG, RC, hippocampus and VMPFC.
Panel B indicates the identified pathways for fact retrieval-related number bisection in a 3D
volume rendering (PIBI values > 0.0148) indicating both ventral connections via the MdLF as
well as dorsal connections encompassing the callosal bundle (depicted in blue). Panel C
again gives a more detailed view on the course of these fiber tracts in axial, sagittal and
coronal orientation.
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Exact/approximate addition task
Fig S3 Mental exact/approximate addition: Results for number magnitude-related
arithmetic (e.g., 54 + 38 = ?)
Panel A reflects cortical regions showing an increase of fMRI signal for the conjunction of
increasing target distance, decreasing decade distance as well as the need for a carry
operation (FWE cluster-threshold corrected p < .05, cluster size k = 15 voxels). Activated
areas for magnitude-related processing include the IPS, pIPS, IFG (BA 45 and BA 47), SMA,
FEF, and the visual number form (VNF), most of them bilaterally. Panel B depicts identified
pathways in a 3D volume rendering with PIBI (probability index forming part of the bundle of
interest) values > 0.0148. For more difficult mental exact/approximate addition a system of
both dorsal (SLF) and ventral external/extreme capsule (EC/emC) connections is recruited
(depicted in red). Panel C shows the respective fiber tracts in axial, sagittal and coronal
orientation specifying dorsal and ventral fiber pathways, encompassing the SLF system and
the EC/EmC system.
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Fig S4 Mental exact/approximate addition: Results for fact retrieval-related arithmetic
(e.g., 14 + 3 = ?)
Panel A reflects cortical regions showing an increase of fMRI signal for the conjunction of
increasing target distance, decreasing decade distance as well as the lack of a carry
operation. Activated areas for fact-retrieval related processing at an FWE cluster-threshold
corrected p < .05 (k = 15 voxels) included the left AG, the retro-splenial cortex (RC),
hippocampus, the (right) SMG, STG, MTG, insula, and the medial FG (VMPFC). Panel B
depicts the identified pathways for fact-retrieval related arithmetic in a 3D volume rendering
(PIBI values > 0.0148) indicating prominent ventral connections encompassing the MdLF and
the EC/EmC system (depicted in blue). Furthermore, a dorsal connection via the callosal
bundle was tracked, linking retro-splenial cortex with VMPFC. Panel C again gives a more
detailed view on the course of the dorsal and ventral fiber tracts in axial, sagittal and coronal
orientation.
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Fig S5 Overlay of fiber tracts identified for number magnitude-related (red) and fact
retrieval-related (blue) number bisection
Panel a depicts seed regions associated with number magnitude processing (red) or fact
retrieval (blue). Panel b reflects the identified pathways in a 3D volume rendering with PIBI
values > 0.0148. Pathways identified for the more difficult magnitude-related conditions are
depicted in red, whereas those reflecting the fact retrieval-related conditions are shown in
blue. Panel c provides a detailed view on the course of the fiber tracts in axial, coronal and
sagittal orientation. Two anatomically largely distinct dorsal vs. ventral fiber pathway profiles
for the processing of number magnitude- and fact retrieval-related problems can be
observed, differing not only in localization of activation but also in the connections between
associated cortical areas and overlapping to a very limited degree only in the vicinity of the
angular gyrus and the EC/EmC system. Additionally, the connection between the visual
number form area (VNF) and the number magnitude representation (IPS/pIPS) is displayed
in red.
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Fig 2 Overlay of fiber tracts identified for number magnitude- (red) and fact retrievalrelated (blue) mental exact/approximate arithmetic
Panel A depicts seed regions associated with number magnitude processing (red) or fact
retrieval (blue). Panel B indicates the identified pathways in a 3D volume rendering with PIBI
values > 0.0148. Pathways identified for the magnitude-related conditions are depicted in
red, whereas those reflecting the fact retrieval-related conditions are shown in blue. Panel C
provides a more detailed view on the course of the fiber tracts in axial, coronal and sagittal
orientation. Comparable with the results for exact/approximate addition, two anatomically
largely distinct dorsal vs. ventral fiber tract profiles can be observed for the processing of
number magnitude-related and the fact retrieval-related triplets, again, differing not only in
localization of activation but also in the connections between associated cortex areas and
overlapping only to a very limited degree in the vicinity of the angular gyrus and the EC/EmC
system. Additionally, the connection between the visual number form area (VNF) and the
number magnitude representation (IPS/pIPS) is displayed in red.
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