Functional Significance of the pre-SMA In MDD: Bridging Networks and Predicting Treatment Efficacy
Poster No:
495
Submission Type:
Abstract Submission
Authors:
zhenxiang zang1, Kaini Qiao2, Zhi Yang2, Gang Wang2
Institutions:
1Beijing Anding Hospital, Beijing, China, 2Beijing Anding Hospital, Beijing, Beijing
First Author:
Co-Author(s):
Introduction:
Recently, an integrative framework has been proposed to explain the imbalance between decreased somatomotor network (SMN) and increased default mode network (DMN) spontaneous activity as a hall marker of MDD (Northoff et al., 2021). The supplementary motor area (SMA) may play a crucial role in mediating the interplay between the SMN and DMN due to it's significance of both anatomical location and function roles (Halsband, Ito, Tanji, & Freund, 1993). In addition, recent study has uncovered it's functional significance in linking the primary motor cortex and prefrontal networks to build up the somato-cognitive action network (Gordon et al., 2023). These evidence demonstrates a possible role of the SMA to bridge the default mode network (DMN) and the SMN as a novel candidate region for neuromodulation targeting.
Methods:
The study has been approved by the ethic committee of Beijing Anding Hospital. The HAMD-17 score was acquired at baseline and after 12 weeks of Escitalopram treatment. Rs-fMRI data from 109 MDD patients and 79 normal controls (NCs) were used for baseline data analyses. Seventy patients returned for 12-week follow-up HAMD examination.
All MRI data were acquired on a 3-T Siemens Prisma scanner with a 64-channel head coil. Rs-fMRI data were preprocessed using the Phipipe toolbox (Hu et al., 2023).
We applied Amplitude of low-frequency fluctuations (ALFF) as the metric to evaluate brain activity. We further computed granger causality from the SMA showing reduced ALFF to the brain to measure SMA effective connectivity. The SMA's activity flow was measured by the multiplication of ALFF and SMA's effective connectivity.
All MRI data were acquired on a 3-T Siemens Prisma scanner with a 64-channel head coil. Rs-fMRI data were preprocessed using the Phipipe toolbox (Hu et al., 2023).
We applied Amplitude of low-frequency fluctuations (ALFF) as the metric to evaluate brain activity. We further computed granger causality from the SMA showing reduced ALFF to the brain to measure SMA effective connectivity. The SMA's activity flow was measured by the multiplication of ALFF and SMA's effective connectivity.
Results:
Significantly reduced ALFF was obtained in the SMA (Figure 1A). The peak voxel is located at [3,12,69] with a T value of -5.30. Cluster showing a significant effect of group for the ANOVA analysis, i.e. NC, MDD(PMR = 0), MDD(PMR = 1), MDD(PMR≥2), was highly consistent with that showing reduced ALFF in the two-sample t-test (Figure 2B). The peak voxel was also located at [3,12,69] with an F value of 11.20.
For MDD patients, significant negative GC connectivity was obtained in the DMN, the SMN, and the frontoparietal network that formed two major components (Figure 2A). The first component explained 19.96% of the total variance and the second component explained 11.82%. The clusters showing the highest PC-1 loading were PCC and MPFC (Figure 2B). The second PC was mainly expressed in the SMN (Figure 2C). The average HAMD reduction rate was 57.6% (Figure 2D). Activity flow from the pre-SMA to the DMN component was significantly correlated with the HAMD reduction rate (R = 0.35, P < 0.01, Figure 2E).
For MDD patients, significant negative GC connectivity was obtained in the DMN, the SMN, and the frontoparietal network that formed two major components (Figure 2A). The first component explained 19.96% of the total variance and the second component explained 11.82%. The clusters showing the highest PC-1 loading were PCC and MPFC (Figure 2B). The second PC was mainly expressed in the SMN (Figure 2C). The average HAMD reduction rate was 57.6% (Figure 2D). Activity flow from the pre-SMA to the DMN component was significantly correlated with the HAMD reduction rate (R = 0.35, P < 0.01, Figure 2E).
Conclusions:
In this study, we found reduced activity of the MDD which was primarily distributed in the pre-supplementary motor area (pre-SMA). The level of pre-SMA activity decreased linearly with the severity of psychomotor retardation (PMR) severity. Second, we found significant negative influence from the pre-SMA to the somatomotor network (SMN) and the default mode network (DMN) in MDD that can be decomsed into a "psycho" component dominated by the DMN, and a "motor " component involving the SMN. Importantly, only activity flow (Cole et al., 2016) of the pre-SMA to the DMN component was correlated with HAMD-17 reduction rate score after 12 weeks of Escitalopram treatment. The pre-SMA connectivity pattern was predominantly expressed in the DMN, consistent with its dense connections to the prefrontal cortex and its role in inhibitory control (Zhang et al., 2017). Taken together, the co-existing of the "psycho" and "motor" components suggest a bridging role of the pre-SMA of the SMN-DMN framework, and that stimulating the pre-SMA may potentially modulate both the "psycho" and the "motor" deficits of MDD.
Disorders of the Nervous System:
Psychiatric (eg. Depression, Anxiety, Schizophrenia) 1
Modeling and Analysis Methods:
Task-Independent and Resting-State Analysis 2
Keywords:
Affective Disorders
Cortex
FUNCTIONAL MRI
Psychiatric Disorders
1|2Indicates the priority used for review
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Provide references using APA citation style.
Gordon, E. M., Chauvin, R. J., Van, A. N., Rajesh, A., Nielsen, A., Newbold, D. J., . . . Dosenbach, N. U. F. (2023). A somato-cognitive action network alternates with effector regions in motor cortex. Nature, 617(7960), 351-359. doi:10.1038/s41586-023-05964-2
Halsband, U., Ito, N., Tanji, J., & Freund, H. J. (1993). The role of premotor cortex and the supplementary motor area in the temporal control of movement in man. Brain, 116 ( Pt 1), 243-266. doi:10.1093/brain/116.1.243
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