Neurochemical profiles of the anterior temporal lobe predict response of repetitive transcranial magnetic stimulation on semantic processing

2021 ◽  
Author(s):  
JeYoung Jung ◽  
Stephen Williams ◽  
Faezeh Sanae Nezhad ◽  
Matthew Lambon Ralph
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Temporal Lobe ◽  
Magnetic Stimulation ◽  
Semantic Processing ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Semantic Representation ◽  
Cortical Region ◽  
Anterior Temporal Lobe ◽  
Neurochemical Profiles

Abstract The effect of repetitive transcranial magnetic stimulation can vary considerably across individuals, but the reasons for this still remain unclear. Here, we investigated whether the response to continuous theta-burst stimulation (cTBS) – an effective protocol for decreasing cortical excitability – related to individual differences in glutamate and GABA neurotransmission. We applied cTBS over the anterior temporal lobe (ATL), a hub for semantic representation, to explore the relationship between the baseline neurochemical profiles in this region and the response to this stimulation. Our experiments revealed that non-responders (subjects who did not show an inhibitory effect of cTBS on subsequent semantic performance) had higher excitatory-inhibitory balance (glutamate + glutamine/GABA ratio) in the ATL, which led to up-regulated task-induced regional activity as well as increased ATL-connectivity with other semantic regions compared to responders. These results disclose that the baseline neurochemical state of a cortical region can be a significant factor in predicting responses to cTBS.

scholarly journals Enhancing vs. inhibiting semantic performance with repetitive transcranial magnetic stimulation over the anterior temporal lobe: frequency- and task- specific effects

2019 ◽  
Author(s):  
JeYoung Jung ◽  
Matthew A. Lambon Ralph
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Temporal Lobe ◽  
Magnetic Stimulation ◽  
Semantic Processing ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Semantic Representation ◽  
Healthy Individuals ◽  
Anterior Temporal Lobe ◽  
Specific Effects ◽  
Virtual Lesion

AbstractAccumulating, converging evidence indicates that the anterior temporal lobe (ATL) appears to be the transmodal hub for semantic representation. A series of repetitive transcranial magnetic stimulation (rTMS) investigations utilizing the ‘virtual lesion’ approach have established the brain-behavioural relationship between the ATL and semantic processing by demonstrating that inhibitory rTMS over the ATL induced impairments in semantic performance in healthy individuals. However, a growing body of rTMS studies suggest that rTMS might also be a tool for cognitive enhancement and rehabilitation, though there has been no previous exploration in semantic cognition. Here, we explored a potential role of rTMS in enhancing and inhibiting semantic performance with contrastive rTMS protocols (1Hz vs. 20Hz) by controlling practice effects. Our results demonstrated that it is possible to modulate semantic performance positively or negatively depending on the ATL stimulation frequency: 20Hz rTMS was optimal for facilitating cortical processing (faster RT in a semantic task) contrasting with diminished semantic performance after 1Hz rTMS. In addition to cementing the importance of the ATL to semantic representation, our findings suggest that 20Hz rTMS leads to semantic enhancement in healthy individuals and potentially could be used for patients with semantic impairments as a therapeutic tool.

Cortical excitability changes after high-frequency repetitive transcranial magnetic stimulation for central poststroke pain

Pain ◽  
2013 ◽  
Vol 154 (8) ◽  
pp. 1352-1357 ◽  
Author(s):  
Koichi Hosomi ◽  
Haruhiko Kishima ◽  
Satoru Oshino ◽  
Masayuki Hirata ◽  
Naoki Tani ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
High Frequency ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation

Low-intensity repetitive transcranial magnetic stimulation decreases motor cortical excitability in humans

2006 ◽  
Vol 101 (2) ◽  
pp. 500-505 ◽  
Author(s):  
Gabrielle Todd ◽  
Stanley C. Flavel ◽  
Michael C. Ridding
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Threshold ◽  
Sham Stimulation ◽  
Motor Cortical Excitability ◽  
Resting Motor Threshold ◽  
Active Motor ◽  
Motor Cortical

Repetitive transcranial magnetic stimulation of the motor cortex (rTMS) can be used to modify motor cortical excitability in human subjects. At stimulus intensities near to or above resting motor threshold, low-frequency rTMS (∼1 Hz) decreases motor cortical excitability, whereas high-frequency rTMS (5–20 Hz) can increase excitability. We investigated the effect of 10 min of intermittent rTMS on motor cortical excitability in normal subjects at two frequencies (2 or 6 Hz). Three low intensities of stimulation (70, 80, and 90% of active motor threshold) and sham stimulation were used. The number of stimuli were matched between conditions. Motor cortical excitability was investigated by measurement of the motor-evoked potential (MEP) evoked by single magnetic stimuli in the relaxed first dorsal interosseus muscle. The intensity of the single stimuli was set to evoke baseline MEPs of ∼1 mV in amplitude. Both 2- and 6-Hz stimulation, at 80% of active motor threshold, reduced the magnitude of MEPs for ∼30 min ( P < 0.05). MEPs returned to baseline values after a weak voluntary contraction. Stimulation at 70 and 90% of active motor threshold and sham stimulation did not induce a significant group effect on MEP magnitude. However, the intersubject response to rTMS at 90% of active motor threshold was highly variable, with some subjects showing significant MEP facilitation and others inhibition. These results suggest that, at low stimulus intensities, the intensity of stimulation may be as important as frequency in determining the effect of rTMS on motor cortical excitability.

scholarly journals Repetitive Transcranial Magnetic Stimulation at Different Sites for Dysphagia After Stroke: A Randomized, Observer-Blind Clinical Trial

2021 ◽  
Vol 12 ◽  
Author(s):  
Lida Zhong ◽  
Jinzhu Rao ◽  
Jing Wang ◽  
Fang Li ◽  
Yang Peng ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Controlled Trial ◽  
Control Group ◽  
Cortical Region ◽  
Stroke Patients ◽  
Swallowing Function ◽  
Group 5

Background: The clinical efficacy of repetitive transcranial magnetic stimulation (rTMS) protocols on patients with poststroke dysphagia is still unclear.Objective: This trial aimed to explore and analyze the effectiveness of 5 Hz rTMS on the unaffected hemisphere, affected hemisphere, and cerebellum in stroke patients with dysphagia.Methods: This observer-blind and randomized controlled trial included a total of 147 patients with stroke. Patients were divided into four treatment groups: the unaffected hemispheric group, the affected hemispheric group, the cerebellum group and the control group. Each group received traditional dysphagia treatment 5 days a week for 2 weeks. All recruited patients except for those in the control group underwent 10 consecutive rTMS sessions for 2 weeks. For the affected hemispheric group and unaffected hemispheric group, 5 Hz rTMS was applied to the affected mylohyoid cortical region or to the unaffected mylohyoid cortical region. For the cerebellum group, 5 Hz rTMS was applied to the mylohyoid cortical representation of the cerebellum (4.3 cm lateral and 2.4 cm below the inion). The Fiberoptic Endoscopic Dysphagia Severity Scale (FEDSS), Penetration/Aspiration Scale (PAS), Gugging Swallowing Screen (GUSS), and Standardized Swallowing Assessment (SSA) were used to evaluate clinical swallowing function before the intervention (baseline), immediately after the intervention and 2 weeks after the intervention.Results: There were significant time and intervention interaction effects on the FEDSS, PAS, SSA, and GUSS scores (p &lt; 0.05). In a direct comparison of the swallowing parameters of the four groups, the changes in FEDSS, PAS, SSA, and GUSS scores showed a significantly greater improvement in the unaffected hemispheric group, the affected hemispheric group and cerebellum group than in the control group (p &lt; 0.05).Conclusions: Whether stimulating the unaffected hemisphere or the affected hemisphere, 5 Hz high-frequency rTMS on mylohyoid cortical tissue might have a positive effect on poststroke patients with dysphagia. In addition, cerebellar rTMS is a safe method that represents a potential treatment for poststroke dysphagia, and more clinical trials are needed to develop this technique further.Clinical Trial Registration:chictr.org.cn, identifier: ChiCTR2000032255.

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