TY - JOUR
T1 - A tug of war
T2 - antagonistic effective connectivity patterns over the motor cortex and the severity of motor symptoms in Gilles de la Tourette syndrome
AU - Zapparoli, Laura
AU - Tettamanti, Marco
AU - Porta, Mauro
AU - Zerbi, Alberto
AU - Servello, Domenico
AU - Banfi, Giuseppe
AU - Paulesu, Eraldo
PY - 2017/9/1
Y1 - 2017/9/1
N2 - We tested the hypothesis that Gilles de la Tourette syndrome (GTS) is characterized by perturbed connectivity within cortico–subcortical motor networks. To this end, we performed a dynamic causal modelling (DCM) analysis of fMRI data collected during a finger opposition task in 24 normal controls and 24 GTS patients. The DCM analysis allowed us to assess whether any GTS-specific patterns of brain activity were related to intrinsic and/or to task-dependent connectivity. While no abnormalities were found for task-dependent connectivity, intrinsic connectivity was abnormally increased in the premotor network, with stronger connections from the supplementary motor area (SMA), from the dorsolateral premotor cortex and from the putamen to the right superior frontal gyrus, an area where GTS showed over-activation in a previous univariate analysis. We also found a positive correlation between the connectivity strength from the right basal ganglia to the right primary motor cortex (M1) and disease severity measured by the Yale Global Tic Severity Scale (YGTSS). This pattern was mirrored by a negative correlation between the connection strength from the right SMA to the right area M1 and the YGTSS score. These two reverse correlation effects showed a specific relationship with individual disease severity: the greater the imbalance between subcortical and premotor connectivity towards area M1, the higher the YGTSS score. These results reveal the existence of perturbed intrinsic connectivity patterns in the motor networks of GTS patients with two competing forces operating in a tug of war-like mechanism: aberrant subcortical afferents to M1, compensated for by inputs from the premotor cortex.
AB - We tested the hypothesis that Gilles de la Tourette syndrome (GTS) is characterized by perturbed connectivity within cortico–subcortical motor networks. To this end, we performed a dynamic causal modelling (DCM) analysis of fMRI data collected during a finger opposition task in 24 normal controls and 24 GTS patients. The DCM analysis allowed us to assess whether any GTS-specific patterns of brain activity were related to intrinsic and/or to task-dependent connectivity. While no abnormalities were found for task-dependent connectivity, intrinsic connectivity was abnormally increased in the premotor network, with stronger connections from the supplementary motor area (SMA), from the dorsolateral premotor cortex and from the putamen to the right superior frontal gyrus, an area where GTS showed over-activation in a previous univariate analysis. We also found a positive correlation between the connectivity strength from the right basal ganglia to the right primary motor cortex (M1) and disease severity measured by the Yale Global Tic Severity Scale (YGTSS). This pattern was mirrored by a negative correlation between the connection strength from the right SMA to the right area M1 and the YGTSS score. These two reverse correlation effects showed a specific relationship with individual disease severity: the greater the imbalance between subcortical and premotor connectivity towards area M1, the higher the YGTSS score. These results reveal the existence of perturbed intrinsic connectivity patterns in the motor networks of GTS patients with two competing forces operating in a tug of war-like mechanism: aberrant subcortical afferents to M1, compensated for by inputs from the premotor cortex.
KW - dynamic causal modelling
KW - effective connectivity
KW - functional magnetic resonance imaging
KW - Gilles de la Tourette syndrome
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U2 - 10.1111/ejn.13658
DO - 10.1111/ejn.13658
M3 - Article
AN - SCOPUS:85029602267
VL - 46
SP - 2203
EP - 2213
JO - European Journal of Neuroscience
JF - European Journal of Neuroscience
SN - 0953-816X
IS - 6
ER -