Comparison of transcranial electrical stimulation regimens for effects on inhibitory circuit activity in primary somatosensory cortex and tactile spatial discrimination performance

α‐tACS over the somatosensory cortex enhances tactile spatial discrimination in healthy subjects with low alpha activity

“…However, it is unclear whether gamma ERS in the primary somatosensory cortex is associated with tactile grating orientation discrimination. We found that the increased cortical activation in the primary somatosensory cortex induced by transcranial random noise stimulation was responsible for an improvement in the tactile grating orientation discrimination (Saito et al., 2019), suggesting that increased gamma ERS in the primary somatosensory cortex improves tactile grating orientation discrimination. Median nerve electrical stimulation was reported to induce ERS in a broad‐frequency band, including the alpha and gamma bands (Dockstader et al., 2008).…”

“…Tactile stimuli were delivered by eight hemispherical domes with different groove widths (3.0, 2.0, 1.5, 1.2, 1.0, 0.75, 0.5, and 0.35 mm) using a custom-made device that automatically controls up-down dome movements (S-16026; Takei Scientific Instruments Co. Ltd., Niigata, Japan) ( Figure 1). The elevation speed of the hemispherical domes was set to 20 mm/s and tactile stimulation duration was set to 1 s based on a previous study (Saito et al, 2018(Saito et al, , 2019. The hemispherical dome was elevated a further 1.5 mm after touching the tip of the right index finger.…”

Grating orientation task trial numbers for short- and long-term tactile discrimination learning

“…Tactile spatial discrimination learning was evaluated using a widely applied GOT [9][10][11] in which subjects received tactile stimuli from eight hemispherical domes with different groove widths (3.0, 2.0, 1.5, 1.2, 1.0, 0.75, 0.5, and 0.35 mm) [12,13]. Stimuli were applied using a custom-made device that automatically controls up-down dome movements (S-16026; Takei Scientific Instruments Co. Ltd., Niigata, Japan).…”

Somatosensory Gating Is Modulated by Anodal Transcranial Direct Current Stimulation

“…Although most tDCS studies have focused on the stimulation effects of primary motor and dorsolateral prefrontal cortices ( Nitsche et al, 2003 ; Fregni et al, 2005 , 2008 ; Antal et al, 2011 ; Ahn et al, 2017 ; Lefaucheur et al, 2017 ; Vanderhasselt et al, 2017 ; Angius et al, 2019 ; Shilo and Lavidor, 2019 ; Chrysikou et al, 2019 ; Gallucci et al, 2020 ), there is evidence that tDCS of the somatosensory cortices can also elicit neurophysiological and psychological after-effects on body processing ( Antal et al, 2006 , 2008 ; Dieckhöfer et al, 2006 ; Lenoir et al, 2017 ; Saito et al, 2019 ). Previous research has established that anodal tDCS of the somatosensory cortex elicits brain hyperexcitability, significant enhancement of pain thresholds ( Matsunaga et al, 2004 ; Antal et al, 2008 ; Grundmann et al, 2011 ; Vaseghi et al, 2015 ), and tactile spatial acuity ( Ragert et al, 2008 ; Fujimoto et al, 2014 , 2016 ), whereas cathodal tDCS can reduce the responsiveness of the primary somatosensory cortex to painful and non-painful stimuli ( Grundmann et al, 2011 ; Lenoir et al, 2017 ).…”