Limits...
Dissociated multimodal hubs and seizures in temporal lobe epilepsy.

Douw L, DeSalvo MN, Tanaka N, Cole AJ, Liu H, Reinsberger C, Stufflebeam SM - Ann Clin Transl Neurol (2015)

Bottom Line: In TLE patients, there was lower overall functional integrity of the DMN as well as an increase in posterior hub connections with other modules.Anatomical between-module connectivity was globally decreased.We provide evidence for dissociated anatomical and functional hub connectivity in TLE.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Charlestown, Massachusetts ; Department of Radiology, Harvard Medical School Boston, Massachusetts ; Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, The Netherlands.

ABSTRACT

Objective: Brain connectivity at rest is altered in temporal lobe epilepsy (TLE), particularly in "hub" areas such as the posterior default mode network (DMN). Although both functional and anatomical connectivity are disturbed in TLE, the relationships between measures as well as to seizure frequency remain unclear. We aim to clarify these associations using connectivity measures specifically sensitive to hubs.

Methods: Connectivity between 1000 cortical surface parcels was determined in 49 TLE patients and 23 controls with diffusion and resting-state functional magnetic resonance imaging. Two types of hub connectivity were investigated across multiple brain modules (the DMN, motor system, etcetera): (1) within-module connectivity (a measure of local importance that assesses a parcel's communication level within its own subnetwork) and (2) between-module connectivity (a measure that assesses connections across multiple modules).

Results: In TLE patients, there was lower overall functional integrity of the DMN as well as an increase in posterior hub connections with other modules. Anatomical between-module connectivity was globally decreased. Higher DMN disintegration (DD) coincided with higher anatomical between-module connectivity, whereas both were associated with increased seizure frequency. DD related to seizure frequency through mediating effects of anatomical connectivity, but seizure frequency also correlated with anatomical connectivity through DD, indicating a complex interaction between multimodal networks and symptoms.

Interpretation: We provide evidence for dissociated anatomical and functional hub connectivity in TLE. Moreover, shifts in functional hub connections from within to outside the DMN, an overall loss of integrative anatomical communication, and the interaction between the two increase seizure frequency.

No MeSH data available.


Related in: MedlinePlus

Within-module DMN+ connections in patients versus controls. Purple nodes indicate the aDMN+ and pDMN+, blue nodes are the parcels outside of the DMN+. (A) Depicts all within-module connections in healthy controls, (B) displays those within-module connections in TLE patients. aDMN+/pDMN+, anterior/posterior default mode newtork; TLE, temporal lobe epilepsy.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4402080&req=5

fig03: Within-module DMN+ connections in patients versus controls. Purple nodes indicate the aDMN+ and pDMN+, blue nodes are the parcels outside of the DMN+. (A) Depicts all within-module connections in healthy controls, (B) displays those within-module connections in TLE patients. aDMN+/pDMN+, anterior/posterior default mode newtork; TLE, temporal lobe epilepsy.

Mentions: Group-level modular topology was spatially investigated by obtaining a “benchmark” healthy modular subdivision, that is, averaging all controls' matrices and performing modularity analysis on this averaged matrix as described previously.38 The same analysis was performed in patients. There were three modules in the healthy benchmark network (Fig.2A). One module spanned areas of the classical DMN, as well as association and frontal cortex, which will be referred to as the DMN+. Another module included the precentral and postcentral gyri, and some superior temporal cortex, which we termed the sensorimotor module (SMM). Finally, a module encompassing visual and parietal areas was termed the parieto-occipital module (POM). In patients, benchmark analysis yielded four modules (Fig.2B), with the DMN+ disconnected into separate anterior and posterior parts (aDMN+ and pDMN+, respectively), as expected and further illustrated in Figure3. When looking at participants' individual modular decomposition, all but one control had intact DMN+ (96%), whereas 27 patients (55%) showed disconnection (chi-square P < 0.001). Of the total 49 patients, 44 had three (20% or 45%) or four (24% or 55%) modules. Three patients had two modules, whereas two patients had five modules. Patients' individual modules particularly overlapped less spatially with the pDMN+, as determined by Dice indices (Table2).39


Dissociated multimodal hubs and seizures in temporal lobe epilepsy.

Douw L, DeSalvo MN, Tanaka N, Cole AJ, Liu H, Reinsberger C, Stufflebeam SM - Ann Clin Transl Neurol (2015)

Within-module DMN+ connections in patients versus controls. Purple nodes indicate the aDMN+ and pDMN+, blue nodes are the parcels outside of the DMN+. (A) Depicts all within-module connections in healthy controls, (B) displays those within-module connections in TLE patients. aDMN+/pDMN+, anterior/posterior default mode newtork; TLE, temporal lobe epilepsy.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402080&req=5

fig03: Within-module DMN+ connections in patients versus controls. Purple nodes indicate the aDMN+ and pDMN+, blue nodes are the parcels outside of the DMN+. (A) Depicts all within-module connections in healthy controls, (B) displays those within-module connections in TLE patients. aDMN+/pDMN+, anterior/posterior default mode newtork; TLE, temporal lobe epilepsy.
Mentions: Group-level modular topology was spatially investigated by obtaining a “benchmark” healthy modular subdivision, that is, averaging all controls' matrices and performing modularity analysis on this averaged matrix as described previously.38 The same analysis was performed in patients. There were three modules in the healthy benchmark network (Fig.2A). One module spanned areas of the classical DMN, as well as association and frontal cortex, which will be referred to as the DMN+. Another module included the precentral and postcentral gyri, and some superior temporal cortex, which we termed the sensorimotor module (SMM). Finally, a module encompassing visual and parietal areas was termed the parieto-occipital module (POM). In patients, benchmark analysis yielded four modules (Fig.2B), with the DMN+ disconnected into separate anterior and posterior parts (aDMN+ and pDMN+, respectively), as expected and further illustrated in Figure3. When looking at participants' individual modular decomposition, all but one control had intact DMN+ (96%), whereas 27 patients (55%) showed disconnection (chi-square P < 0.001). Of the total 49 patients, 44 had three (20% or 45%) or four (24% or 55%) modules. Three patients had two modules, whereas two patients had five modules. Patients' individual modules particularly overlapped less spatially with the pDMN+, as determined by Dice indices (Table2).39

Bottom Line: In TLE patients, there was lower overall functional integrity of the DMN as well as an increase in posterior hub connections with other modules.Anatomical between-module connectivity was globally decreased.We provide evidence for dissociated anatomical and functional hub connectivity in TLE.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Charlestown, Massachusetts ; Department of Radiology, Harvard Medical School Boston, Massachusetts ; Department of Anatomy and Neurosciences, VU University Medical Center Amsterdam, The Netherlands.

ABSTRACT

Objective: Brain connectivity at rest is altered in temporal lobe epilepsy (TLE), particularly in "hub" areas such as the posterior default mode network (DMN). Although both functional and anatomical connectivity are disturbed in TLE, the relationships between measures as well as to seizure frequency remain unclear. We aim to clarify these associations using connectivity measures specifically sensitive to hubs.

Methods: Connectivity between 1000 cortical surface parcels was determined in 49 TLE patients and 23 controls with diffusion and resting-state functional magnetic resonance imaging. Two types of hub connectivity were investigated across multiple brain modules (the DMN, motor system, etcetera): (1) within-module connectivity (a measure of local importance that assesses a parcel's communication level within its own subnetwork) and (2) between-module connectivity (a measure that assesses connections across multiple modules).

Results: In TLE patients, there was lower overall functional integrity of the DMN as well as an increase in posterior hub connections with other modules. Anatomical between-module connectivity was globally decreased. Higher DMN disintegration (DD) coincided with higher anatomical between-module connectivity, whereas both were associated with increased seizure frequency. DD related to seizure frequency through mediating effects of anatomical connectivity, but seizure frequency also correlated with anatomical connectivity through DD, indicating a complex interaction between multimodal networks and symptoms.

Interpretation: We provide evidence for dissociated anatomical and functional hub connectivity in TLE. Moreover, shifts in functional hub connections from within to outside the DMN, an overall loss of integrative anatomical communication, and the interaction between the two increase seizure frequency.

No MeSH data available.


Related in: MedlinePlus