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Beynel L, Powers JP, Appelbaum LG. Effects of repetitive transcranial magnetic stimulation on resting-state connectivity: A systematic review. Neuroimage 2020; 211:116596. [PMID: 32014552 PMCID: PMC7571509 DOI: 10.1016/j.neuroimage.2020.116596] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/17/2019] [Accepted: 01/30/2020] [Indexed: 01/02/2023] Open
Abstract
The brain is organized into networks that reorganize dynamically in response to cognitive demands and exogenous stimuli. In recent years, repetitive transcranial magnetic stimulation (rTMS) has gained increasing use as a noninvasive means to modulate cortical physiology, with effects both proximal to the stimulation site and in distal areas that are intrinsically connected to the proximal target. In light of these network-level neuromodulatory effects, there has been a rapid growth in studies attempting to leverage information about network connectivity to improve neuromodulatory control and intervention outcomes. However, the mechanisms-of-action of rTMS on network-level effects remain poorly understood and is based primarily on heuristics from proximal stimulation findings. To help bridge this gap, the current paper presents a systematic review of 33 rTMS studies with baseline and post-rTMS measures of fMRI resting-state functional connectivity (RSFC). Literature synthesis revealed variability across studies in stimulation parameters, studied populations, and connectivity analysis methodology. Despite this variability, it is observed that active rTMS induces significant changes on RSFC, but the prevalent low-frequency-inhibition/high-frequency-facilitation heuristic endorsed for proximal rTMS effects does not fully describe distal connectivity findings. This review also points towards other important considerations, including that the majority of rTMS-induced changes were found outside the stimulated functional network, suggesting that rTMS effects tend to spread across networks. Future studies may therefore wish to adopt conventions and systematic frameworks, such as the Yeo functional connectivity parcellation atlas adopted here, to better characterize network-level effect that contribute to the efficacy of these rapidly developing noninvasive interventions.
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Affiliation(s)
- Lysianne Beynel
- Department of Psychiatry and Behavioral Science, Duke University School of Medicine, United States.
| | - John Paul Powers
- Department of Psychology and Neuroscience, Duke University, United States
| | - Lawrence Gregory Appelbaum
- Department of Psychiatry and Behavioral Science, Duke University School of Medicine, United States; Center for Cognitive Neuroscience, Duke University, United States
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Walters MJ, Ebsworth K, Berahovich RD, Penfold MET, Liu SC, Al Omran R, Kioi M, Chernikova SB, Tseng D, Mulkearns-Hubert EE, Sinyuk M, Ransohoff RM, Lathia JD, Karamchandani J, Kohrt HEK, Zhang P, Powers JP, Jaen JC, Schall TJ, Merchant M, Recht L, Brown JM. Inhibition of CXCR7 extends survival following irradiation of brain tumours in mice and rats. Br J Cancer 2014; 110:1179-88. [PMID: 24423923 PMCID: PMC3950859 DOI: 10.1038/bjc.2013.830] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 12/12/2013] [Accepted: 12/18/2013] [Indexed: 12/26/2022] Open
Abstract
Background: In experimental models of glioblastoma multiforme (GBM), irradiation (IR) induces local expression of the chemokine CXCL12/SDF-1, which promotes tumour recurrence. The role of CXCR7, the high-affinity receptor for CXCL12, in the tumour's response to IR has not been addressed. Methods: We tested CXCR7 inhibitors for their effects on tumour growth and/or animal survival post IR in three rodent GBM models. We used immunohistochemistry to determine where CXCR7 protein is expressed in the tumours and in human GBM samples. We used neurosphere formation assays with human GBM xenografts to determine whether CXCR7 is required for cancer stem cell (CSC) activity in vitro. Results: CXCR7 was detected on tumour cells and/or tumour-associated vasculature in the rodent models and in human GBM. In human GBM, CXCR7 expression increased with glioma grade and was spatially associated with CXCL12 and CXCL11/I-TAC. In the rodent GBM models, pharmacological inhibition of CXCR7 post IR caused tumour regression, blocked tumour recurrence, and/or substantially prolonged survival. CXCR7 expression levels on human GBM xenograft cells correlated with neurosphere-forming activity, and a CXCR7 inhibitor blocked sphere formation by sorted CSCs. Conclusions: These results indicate that CXCR7 inhibitors could block GBM tumour recurrence after IR, perhaps by interfering with CSCs.
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Affiliation(s)
- M J Walters
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - K Ebsworth
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - R D Berahovich
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - M E T Penfold
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - S-C Liu
- Department of Radiation Oncology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - R Al Omran
- Department of Radiation Oncology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - M Kioi
- Department of Radiation Oncology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - S B Chernikova
- Department of Radiation Oncology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - D Tseng
- Department of Radiation Oncology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - E E Mulkearns-Hubert
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - M Sinyuk
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - R M Ransohoff
- 1] Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA [2] Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - J D Lathia
- 1] Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA [2] Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - J Karamchandani
- Department of Pathology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - H E K Kohrt
- Department of Medicine, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - P Zhang
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - J P Powers
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - J C Jaen
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - T J Schall
- ChemoCentryx Inc., 850 Maude Ave, Mountain View, CA 94043, USA
| | - M Merchant
- Department of Neurology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - L Recht
- Department of Neurology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - J M Brown
- Department of Radiation Oncology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
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