Transcranial direct current stimulation applied over the somatosensory cortex – Differential effect on low and high frequency SEPs

Anodal transcranial direct current stimulation (a-tDCS) of primary somatosensory cortex (S1) has been shown to enhance tactile spatial acuity, but there is little information as to the underlying neuronal mechanisms. We examined vibrotactile perception on the distal phalanx of the middle finger before, during, and after contralateral S1 tDCS [a-, cathodal (c)-, and sham (s)-tDCS]. The experiments tested our shift-gain hypothesis, which predicted that a-tDCS would decrease vibrotactile detection and discrimination thresholds (leftward shift of the stimulus-response function with increased gain/slope) relative to s-tDCS, whereas c-tDCS would have the opposite effects (relative to s-tDCS). The results showed that weak a-tDCS (1 mA, 20 min) led to a reduction in both vibrotactile detection and discrimination thresholds to 73–76% of baseline during the application of the stimulation in subjects categorized as responders. These effects persisted after the end of a-tDCS but were absent 30 min later. Most, but not all, subjects showed a decrease in threshold (8/12 for detection; 9/12 for discrimination). Intersubject variability was explained by a ceiling effect in the discrimination task. c-tDCS had no significant effect on either detection or discrimination threshold. Taken together, our results supported our shift-gain hypothesis for a-tDCS but not c-tDCS.

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P101 Assymetric immediate and long-term effects induced by transcranial direct current stimulation on alert mice somatosensory cortex

Clinical Neurophysiology ◽

10.1016/j.clinph.2019.12.212 ◽

2020 ◽

Vol 131 (4) ◽

pp. e69

Author(s):

C.A. Sanchez Leon ◽

I. Cordones Cano ◽

M.D.L. Gomez Climent ◽

A. Carretero Guillen ◽

G. Cheron ◽

...

Keyword(s):

Somatosensory Cortex ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Long Term Effects ◽

Direct Current Stimulation

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Transcranial Direct Current Stimulation Over Somatosensory Cortex Decreases ExperimentallyInduced Acute Pain Perception

Clinical Journal of Pain ◽

10.1097/ajp.0b013e318157233b ◽

2008 ◽

Vol 24 (1) ◽

pp. 56-63 ◽

Cited By ~ 111

Author(s):

Andrea Antal ◽

Nadine Brepohl ◽

Csaba Poreisz ◽

Klara Boros ◽

Gabor Csifcsak ◽

...

Keyword(s):

Somatosensory Cortex ◽

Direct Current ◽

Acute Pain ◽

Transcranial Direct Current Stimulation ◽

Pain Perception ◽

Direct Current Stimulation

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Dose response of somatosensory cortex repeated anodal transcranial direct current stimulation on vibrotactile detection: a randomized sham-controlled trial

Journal of Neurophysiology ◽

10.1152/jn.00926.2017 ◽

2018 ◽

Vol 120 (2) ◽

pp. 610-616 ◽

Cited By ~ 1

Author(s):

Brookes Folmli ◽

Bulent Turman ◽

Peter Johnson ◽

Allan Abbott

Keyword(s):

Direct Current ◽

Dose Response ◽

Transcranial Direct Current Stimulation ◽

High Frequency ◽

Controlled Trial ◽

Low Frequency ◽

Dominant Hand ◽

Detection Thresholds ◽

Direct Current Stimulation ◽

Nondominant Hand

This randomized sham-controlled trial investigated anodal transcranial direct current stimulation (tDCS) over the somatosensory cortex contralateral to hand dominance for dose-response (1 mA, 20 min × 5 days) effects on vibrotactile detection thresholds (VDT). VDT was measured before and after tDCS on days 1, 3, and 5 for low- (30 Hz) and high-frequency (200 Hz) vibrations on the dominant and nondominant hands in 29 healthy adults (mean age = 22.86 yr; 15 men, 14 women). Only the dominant-hand 200-Hz VDT displayed statistically significant medium effect size improvement for mixed-model analysis of variance time-by-group interaction for active tDCS compared with sham. Post hoc contrasts were statistically significant for dominant-hand 200-Hz VDT on day 5 after tDCS compared with day 1 before tDCS, day 1 after tDCS, and day 3 before tDCS. There was a linear dose-response improvement with dominant-hand 200-Hz VDT mean difference decreasing from day 1 before tDCS peaking at −15.5% (SD = 34.9%) on day 5 after tDCS. Both groups showed learning effect trends over time for all VDT test conditions, but only the nondominant-hand 30-Hz VDT was statistically significant ( P = 0.03), although post hoc contrasts were nonsignificant after Šidák adjustment. No adverse effects for tDCS were reported. In conclusion, anodal tDCS at 1 mA, 20 min × 5 days on the dominant sensory cortex can modulate a linear improvement of dominant-hand high-frequency VDT but not low-frequency or nondominant-hand VDT. NEW & NOTEWORTHY Repeated weak anodal transcranial direct current stimulation (1 mA, 20 min) on the dominant sensory cortex provides linear improvement in dominant-hand high-frequency vibration detection thresholds. No effects were observed for low-frequency or nondominant-hand vibration detection thresholds.

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A Modified Hodgkin-Huxley model to Show the Effect of Motor Cortex Stimulation on the Trigeminal Neuralgia Network

10.1101/467100 ◽

2018 ◽

Author(s):

Mohammadreza Khodashenas ◽

Golnaz Baghdadi ◽

Farzad Towhidkhah

Keyword(s):

Motor Cortex ◽

Trigeminal Neuralgia ◽

Somatosensory Cortex ◽

Sodium Channels ◽

Trigeminal Nerve ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Direct Current Stimulation ◽

Proposed Model ◽

The Relationship

AbstractBackgroundTrigeminal neuralgia (TN) is a severe neuropathic pain, which has an electric shock like characteristic. There are some common treatments for this pain such as medicine, microvascular decompression or radio frequency. In this regard, transcranial direct current stimulation (tDCS) is another therapeutic method to reduce the pain, which has been recently attracting the therapists’ attention. The positive effect of tDCS on TN was shown in many previous studies. However, the mechanism of tDCS effect has remained unclearObjectiveThis study aims to model the neuronal behavior of the main known regions of the brain participating in TN pathways to study the effect of transcranial direct current stimulationMethodThe proposed model consists of several blocks (block diagram): 1) trigeminal nerve, 2) trigeminal ganglion, 3) PAG (Periaqueductal gray in the brainstem), 4) thalamus, 5) motor cortex (M1) and 6) somatosensory cortex (S1). Each of these components represented by a modified Hodgkin-Huxley (HH) model (a mathematical model). The modification of the HH model was done based on some neurological facts of pain sodium channels. The input of the model is any stimuli to ‘trigeminal nerve,’ which cause the pain, and the output is the activity of the somatosensory cortex. An external current, which is considered as electrical current, was applied to the motor cortex block of the modelResultThe results showed that by decreasing the conductivity of the slow sodium channels (pain channels) and applying tDCS over the M1, the activity of the somatosensory cortex would be reduced. This reduction can cause pain reliefConclusionThe proposed model provided some possible suggestions about the relationship between the effects of tDCS and associated components in TN, and also the relationship between the pain measurement index, somatosensory cortex activity, and the strength of tDCS.

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Immediate and after effects of transcranial direct-current stimulation in the mouse primary somatosensory cortex

Scientific Reports ◽

10.1038/s41598-021-82364-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Carlos A. Sánchez-León ◽

Isabel Cordones ◽

Claudia Ammann ◽

José M. Ausín ◽

María A. Gómez-Climent ◽

...

Keyword(s):

Somatosensory Cortex ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Immunohistochemical Analysis ◽

Gamma Oscillations ◽

Primary Somatosensory Cortex ◽

After Effects ◽

Direct Current Stimulation ◽

Sensory Evoked ◽

Cathodal Stimulation

AbstractTranscranial direct-current stimulation (tDCS) is a non-invasive brain stimulation technique consisting in the application of weak electric currents on the scalp. Although previous studies have demonstrated the clinical value of tDCS for modulating sensory, motor, and cognitive functions, there are still huge gaps in the knowledge of the underlying physiological mechanisms. To define the immediate impact as well as the after effects of tDCS on sensory processing, we first performed electrophysiological recordings in primary somatosensory cortex (S1) of alert mice during and after administration of S1-tDCS, and followed up with immunohistochemical analysis of the stimulated brain regions. During the application of cathodal and anodal transcranial currents we observed polarity-specific bidirectional changes in the N1 component of the sensory-evoked potentials (SEPs) and associated gamma oscillations. On the other hand, 20 min of cathodal stimulation produced significant after-effects including a decreased SEP amplitude for up to 30 min, a power reduction in the 20–80 Hz range and a decrease in gamma event related synchronization (ERS). In contrast, no significant changes in SEP amplitude or power analysis were observed after anodal stimulation except for a significant increase in gamma ERS after tDCS cessation. The polarity-specific differences of these after effects were corroborated by immunohistochemical analysis, which revealed an unbalance of GAD 65–67 immunoreactivity between the stimulated versus non-stimulated S1 region only after cathodal tDCS. These results highlight the differences between immediate and after effects of tDCS, as well as the asymmetric after effects induced by anodal and cathodal stimulation.

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