Enhanced Control of Cortical Pyramidal Neurons With Micromagnetic Stimulation

Lee, Seung Woo; Fried, Shelley I.

doi:10.1109/tnsre.2016.2631446

Cited by 56 publications

(73 citation statements)

References 49 publications

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“…In the in vivo experiments, it was demonstrated that μMS of the DCN resulted in the generation of neuronal activities in the IC and in the cochlea. The in vivo experiments have recently been extended to the feline cochlea ( Lee and Fried, 2017 ). Hence, μMS can elicit neuronal activation within an interconnected neural circuit and is not restricted to modulation of only local circuitry.…”

Section: Resultsmentioning

confidence: 99%

Solenoidal Micromagnetic Stimulation Enables Activation of Axons With Specific Orientation

et al. 2018

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Electrical stimulation of the central and peripheral nervous systems - such as deep brain stimulation, spinal cord stimulation, and epidural cortical stimulation are common therapeutic options increasingly used to treat a large variety of neurological and psychiatric conditions. Despite their remarkable success, there are limitations which if overcome, could enhance outcomes and potentially reduce common side-effects. Micromagnetic stimulation (μMS) was introduced to address some of these limitations. One of the most remarkable properties is that μMS is theoretically capable of activating neurons with specific axonal orientations. Here, we used computational electromagnetic models of the μMS coils adjacent to neuronal tissue combined with axon cable models to investigate μMS orientation-specific properties. We found a 20-fold reduction in the stimulation threshold of the preferred axonal orientation compared to the orthogonal direction. We also studied the directional specificity of μMS coils by recording the responses evoked in the inferior colliculus of rodents when a pulsed magnetic stimulus was applied to the surface of the dorsal cochlear nucleus. The results confirmed that the neuronal responses were highly sensitive to changes in the μMS coil orientation. Accordingly, our results suggest that μMS has the potential of stimulating target nuclei in the brain without affecting the surrounding white matter tracts.

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Section: Resultsmentioning

confidence: 99%

Solenoidal Micromagnetic Stimulation Enables Activation of Axons With Specific Orientation

et al. 2018

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“…This capacitance was also shown by the fact that dendritic activation needed longer rTMS trains (i.e. more energy), but when they are eventually activated, they fired with higher amplitudes and for a longer period after stimulation ceases (Lee and Fried 2017). A similar effect was shown in single neurons where current injection into dendrites furthest from the soma produced longer and larger action potentials compared to somatic current injection (Larkum et al 2007), especially in response to higher frequency and longer pulse width stimulation (Ledergerber and Larkum 2010).…”

Section: Discussionmentioning

confidence: 84%

Increasing pulse energy of 5Hz rTMS improves its efficacy in inducing excitatory aftereffects

Halawa

Reichert

Anil

et al. 2019

Preprint

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Introduction:High frequency repetitive transcranial magnetic stimulation induces excitation when applied to the motor cortex, as measured by increased amplitudes of motor evoked potentials (MEPs) after the intervention. Different pulse widths induce different effects, likely by primarily stimulating distinct segments of neurons due to the different membrane properties of different neuronal segments.Here we focus on the aftereffects generated with high frequencies of controllable pulse TMS (cTMS).Objectives: To investigate the influence of different stimulation intensities, pulse widths and direction of high frequency rTMS on its excitatory plastic aftereffects as reflected by MEP amplitudes. Methods:Using a controllable pulse stimulator TMS (cTMS), we stimulated the hand motor cortex of 20 healthy subjects with 5 Hz rTMS with 1200 bidirectional pulses with the main component widths of 80 and 120 microseconds. 80% resting motor threshold (RMT) intensity was investigated for both directions anterior-posterior (AP) and vice versa (PA), and at 90% RMT in the AP direction for the second experiment.Results: 80% HF rTMS did not produce any significant excitation in both AP and PA directions. 90% RMT AP stimulation exhibited a significant excitation aftereffect with the 120 microseconds wide pulses, whereas the 80 microseconds failed to produce significant excitation. Conclusions:Higher intensity and longer HF pulse rTMS are more efficient in producing excitatory aftereffects, this may be due to the different membrane properties of the various neuronal segments such as dendrites whose activation plays a major role in long term potentiation.Significance: The findings here may contribute to better results in future clinical studies performed with longer cTMS pulses. Figure 1: Diagram of the experiment timeline for each session of the experiment. Methods: ParticipantsFor the first experiment, we recruited fourteen subjects, four males and ten females, mean age was 23.5 ± 2.6 SD years. For the second experiment, a different set of fifteen healthy volunteers was recruited, four males and eleven females, the mean age was 24.1 ± 3.1 SD years. All participants were right-handed and free from any neurological or psychiatric disorders, took no centrally acting medications, and had no contraindications to TMS. Because the power cap of the device and the standard coil for the wider pulse shapes prevented intensities above 50% of maximal stimulator output (MSO), a higher resting motor threshold, i.e. above 70% MSO for a Magstim 200 2 device, was an exclusion criterion.We obtained written informed consent from each subject before participation.The local ethics committee of the University Medical Center Göttingen approved the study protocol, which conformed to the Declaration of Helsinki. RecordingsMotor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) muscle of the right hand with surface Ag-AgCl electrodes in a belly-tendon montage. The electromyography signals were amplified, band-pass filtered (2 Hz-2...

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“…Implantable magnetic stimulation was recently suggested and studied for its feasibility in in vitro 18 and in vivo 20 conditions, suppression of subthalamic nucleus activity 19 , eliciting neural activities of cortical pyramidal neurons 22 , and development of penetrating-type stimulating microcoils 2 . Although neuromodulation effects using coils developed by each research team have been extensively studied, there has been little research on the heat generated around the coil during magnetic stimulation.…”

Section: Discussionmentioning

confidence: 99%

“…The temperature rise did not significantly modulate synaptic activities in the hippocampal slice. In the future, the molecular and cellular mechanisms of CMS need to be further investigated using methods such as a western blotting 60 or immunohistochemistry 61 , 62 to analyze the variation of crucial proteins for synaptic LTD; calcium imaging 63 to confirm calcium signaling in network-level; Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) to detect possible cell depth 64 , 65 ; patch-clamp recording using various receptor blockers 22 , 29 , 31 ; input-output curve for analyzing basal synaptic transmission 44 ; paired-pulse ratio to measure the short-term plasticity in the presynaptic terminal. Also, more experimental studies using various combinations of CMS parameters such as pulse width, ISI, ITI and duration of stimulation are desired.…”

Section: Discussionmentioning

confidence: 99%

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Planar coil-based contact-mode magnetic stimulation: synaptic responses in hippocampal slices and thermal considerations

Park

Kang

et al. 2018

Sci Rep

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Implantable magnetic stimulation is an emerging type of neuromodulation using coils that are small enough to be implanted in the brain. A major advantage of this method is that stimulation performance could be sustained even though the coil is encapsulated by gliosis due to foreign body reactions. Magnetic fields can induce indirect electric fields and currents in neurons. Compared to transcranial magnetic stimulation, the coil size used in implantable magnetic stimulation can be greatly reduced. However, the size reduction is accompanied by an increase in coil resistance. Hence, the coil could potentially damage neurons from the excess heat generated. Therefore, it is necessary to study the stimulation performance and possible thermal damage by implantable magnetic stimulation. Here, we devised contact-mode magnetic stimulation (CMS), wherein magnetic stimulation was applied to hippocampal slices through a customized planar-type coil underneath the slice in the contact mode. With acute hippocampal slices, we investigated the synaptic responses to examine the field excitatory postsynaptic responses of CMS and the temperature rise during CMS. A long-lasting synaptic depression was exhibited in the CA1 stratum radiatum after CMS, while the temperature remained in a safe range so as not to seriously affect the neural responses.

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Enhanced Control of Cortical Pyramidal Neurons With Micromagnetic Stimulation

Cited by 56 publications

References 49 publications

Solenoidal Micromagnetic Stimulation Enables Activation of Axons With Specific Orientation

Solenoidal Micromagnetic Stimulation Enables Activation of Axons With Specific Orientation

Increasing pulse energy of 5Hz rTMS improves its efficacy in inducing excitatory aftereffects

Planar coil-based contact-mode magnetic stimulation: synaptic responses in hippocampal slices and thermal considerations

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