Glutamate-Weighted Magnetic Resonance Imaging (GluCEST) Detects Effects of Transcranial Magnetic Stimulation to the Motor Cortex

Cember, Abigail; Deck, Benjamin L.; Kelkar, Apoorva; Faseyitan, Olufunsho; Zimmerman, Jared P.; Erickson, Brian; Elliott, Mark A.; Coslett, H. Branch; Hamilton, Roy H.; Reddy, Ravinder; Medaglia, John D.

doi:10.1016/j.neuroimage.2022.119191

Cited by 11 publications

(12 citation statements)

References 54 publications

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“…Another mechanism that might contribute to the difference of FA changes after excitatory and inhibitory rTMS is the differential neurotransmitter concentration across cortical layers. A recent examination of the glutamate signal changes in response to theta‐burst stimulation indicated a pattern of decreases in the ipsilateral hemisphere 11 . This might underpin our observed changes that after rTMS excitation, the FA values of ipsilateral regions were more likely to change while after rTMS inhibition, the FA values of contralateral were more likely to change.…”

Section: Discussionsupporting

confidence: 53%

“…9,10 In the past two decades, neuroimaging studies have provided insights into how TMS affects brain in anatomy, function, and chemistry. For example, magnetic resonance spectroscopy studies have demonstrated changes in γ-aminobutyric acid concentrations in relation to TMS-based changes in brain electrophysiology, 11,12 and positron emission tomography studies of regional cerebral blood flow/glucose metabolic rate have shown changes after long stimulation. 13 Functional magnetic resonance imaging (fMRI) has also been used to document the acute impact of TMS on brain networks, 14 which has shown that rTMS-induced functional changes tend to spread distally across and within networks.…”

mentioning

confidence: 99%

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The acute effects of repetitive transcranial magnetic stimulation on laminar diffusion anisotropy of neocortical gray matter

Zhang

Liu

Zhao

et al. 2023

MedComm

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Repetitive transcranial magnetic stimulation (rTMS) is increasingly used to treat neuropsychiatric disorders. Inhibitory and excitatory regimens have been both adopted but the exact mechanism of action remains unclear, and investigating their differential effects on laminar diffusion profiles of neocortex may add important evidence. Twenty healthy participants were randomly assigned to receive a low‐frequency/inhibitory or high‐frequency/excitatory rTMS targeting the left dorsolateral prefrontal cortex (DLPFC). With the brand‐new submillimeter diffusion tensor imaging of whole brain and specialized surface‐based laminar analysis, fractional anisotropy (FA) and mean diffusion (MD) profiles of cortical layers at different cortical depths were characterized before/after rTMS. Inhibitory and excitatory rTMS both showed impacts on diffusion metrics of somatosensory, limbic, and sensory regions, but different patterns of changes were observed—increased FA with inhibitory rTMS, whereas decreased FA with excitatory rTMS. More importantly, laminar analysis indicated laminar specificity of changes in somatosensory regions during different rTMS patterns—inhibitory rTMS affected the superficial layers contralateral to the DLPFC, while excitatory rTMS led to changes in the intermediate/deep layers bilateral to the DLPFC. These findings provide novel insights into acute neurobiological effects on diffusion profiles of rTMS that may add critical evidence relevant to different protocols of rTMS on neocortex.

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Section: Discussionsupporting

confidence: 53%

mentioning

confidence: 99%

The acute effects of repetitive transcranial magnetic stimulation on laminar diffusion anisotropy of neocortical gray matter

Zhang

Liu

Zhao

et al. 2023

MedComm

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“…Recently, our group has used gluCEST to study the effects on healthy volunteers of transcranial magnetic stimulation (TMS). 65,66 TMS is a type of non-invasive brain stimulation that uses a strong and rapidly fluctuating electrical current transmitted through loops of conductive wires in close proximity to the skull (see bottom right portion of Figure 16). The magnetic field generated by the current penetrates the scalp and skull, inducing electrical and, presumably, subsequent chemical changes within the cortex.…”

Section: Emerging Applicationsmentioning

confidence: 99%

Glutamate‐weighted CEST (gluCEST) imaging for mapping neurometabolism: An update on the state of the art and emerging findings from in vivo applications

2022

Self Cite

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Glutamate is the primary excitatory neurotransmitter in the mammalian central nervous system. As such, its proper regulation is essential to the healthy function of the human brain, and dysregulation of glutamate metabolism and compartmentalization underlies numerous neurological and neuropsychiatric pathologies. Glutamate‐weighted chemical exchange saturation transfer (gluCEST) MRI is one of the only ways to non‐invasively observe the relative concentration and spatial distribution of glutamate in the human brain. In the past 10 years, gluCEST has developed from a proof‐of‐concept experiment carried out in imaging phantoms and model systems to an increasingly sophisticated technique applied to reveal deviations from baseline neural metabolism in human beings, most notably in patients experiencing seizures of various origins or those on the psychosis spectrum. This article traces that progress, including in‐depth discussion of the technical specifics of gluCEST and potential challenges to performing these experiments rigorously. We discuss the neurobiological context of glutamate, including the widely accepted hypotheses and models in the literature regarding its involvement in neurodegenerative diseases and other pathology. We then review the state of the art of in vivo glutamate detection by magnetic resonance imaging and the limitations on this front of in vivo MR spectroscopy. The gluCEST experiment is introduced and its advantages, challenges and limitations are thoroughly explored, beginning with the phantom experiment results demonstrated in the initial publication, through the latest approaches to correcting human brain images for B1 inhomogeneity. We then give a comprehensive overview of preclinical applications demonstrated to date, including Alzheimer's disease, Parkinson's disease, Huntington's disease, Traumatic brain injury and cancer, followed by a similar discussion of human studies. Finally, we highlight emerging applications, and discuss technical improvements on the horizon that hold promise for improving the robustness and versatility of gluCEST and its increasing presence in the arena of translational and precision medicine.

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“…[12,14] Other studies have shown that magnetic stimulation can be applied to the respiratory motor cortex to improve respiratory function. [15,16] The cortical location of rTMS-induced unilateral diaphragmatic response is the contralateral brain region, which is reported to be 3 cm outside the midline and 2 to 3 cm in front of the ear plane (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Assessing the effect of transcranial magnetic stimulation on peak cough flow in patients with supratentorial cerebral infarction: A retrospective cohort study

Yoo¹,

Park²

2023

Medicine

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Respiratory dysfunction following supratentorial cerebral infarction leads to pneumonia and is a major cause of mortality. Decreased voluntary cough function impairs the ability to clear mucus or secretions from the airways and increases the risk of aspiration pneumonia. Peak cough flow (PCF) is one of the objective tools for evaluating voluntary cough function. Repetitive transcranial magnetic stimulation (rTMS) could be applied to the respiratory motor cortex to improve respiratory function. Little is known about the effect of rTMS on PCF in patients with supratentorial cerebral infarction during the subacute period. This study aimed to determine whether rTMS treatment could improve PCF in patients with supratentorial cerebral infarction. We retrospectively recruited patients with subacute supratentorial cerebral infarction who underwent a PCF test. The rTMS group received a combination of rTMS treatment for 2 weeks and conventional rehabilitation for 4 weeks. However, the control group underwent only conventional rehabilitation for 4 weeks. PCF tests were performed before and after treatment and the results were compared between the 2 groups. In total, 145 patients with supratentorial cerebral infarctions were recruited. The PCF parameters before and after treatment increased in both the rTMS and control groups. However, the rTMS group showed a greater increase in PCF values compared with the control group. In patients with supratentorial cerebral infarction, the combination of conventional rehabilitation and rTMS in the subacute period may be helpful in improving voluntary cough function compared with conventional rehabilitation alone.

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Glutamate-Weighted Magnetic Resonance Imaging (GluCEST) Detects Effects of Transcranial Magnetic Stimulation to the Motor Cortex

Cited by 11 publications

References 54 publications

The acute effects of repetitive transcranial magnetic stimulation on laminar diffusion anisotropy of neocortical gray matter

The acute effects of repetitive transcranial magnetic stimulation on laminar diffusion anisotropy of neocortical gray matter

Glutamate‐weighted CEST (gluCEST) imaging for mapping neurometabolism: An update on the state of the art and emerging findings from in vivo applications

Assessing the effect of transcranial magnetic stimulation on peak cough flow in patients with supratentorial cerebral infarction: A retrospective cohort study

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