Transcranial direct current stimulation (tDCS) produces localized and specific alterations in neurochemistry: A 1H magnetic resonance spectroscopy study

doi:10.1016/j.neulet.2011.05.244

Neuroscience Letters

Volume 500, Issue 1, 1 August 2011, Pages 67-71

https://doi.org/10.1016/j.neulet.2011.05.244 Get rights and content

Abstract

Transcranial direct current stimulation (tDCS) has been found to produce significant changes in behavior, including a large increase of learning and performance for a difficult visual perceptual task (Clark et al., NeuroImage 2010). The mechanisms by which tDCS produces these behavioral effects are currently uncertain. One hypothesis is that anodal tDCS leads to increased metabolic activity in the brain, which enhances cognitive and memory processes. Here we examined the neuronal mechanisms by which tDCS influences learning by measuring changes in brain metabolite concentrations using proton magnetic resonance spectroscopy (¹H MRS). As perception and learning can also influence neurochemistry, here we applied tDCS during rest. MRS data was obtained before and after 2.0 mA of anodal tDCS was applied for 30 min over electrode site P4, with the cathode placed on the contralateral arm. MRS data were acquired from the right parietal lobe beneath the anodal tDCS electrode, and from the homologous regions of the left hemisphere once before and once after tDCS. Significantly higher combined glutamate and glutamine levels were found in right parietal cortex, beneath the stimulating electrode, with non-significant increases in homologous regions of the opposite hemisphere. In addition, a significant interaction between hemispheres was found for tDCS effects on tNAA. These results suggest that changes in glutamatergic activity and tNAA may be related to the mechanisms by which tDCS influences learning and behavior.

Highlights

► We have previously found that tDCS produces a large increase in learning. ► Here we examined the neurochemical effects of this tDCS protocol using ¹H MRS. ► Data was acquired underneath and contralateral to the stimulating electrode. ► Glutamatergic metabolites and NAA were significantly increased. ► tDCS may increase neurometabolic activity locally, resulting in behavioral changes.

Section snippets

Acknowledgement

This work was supported by the Department of Energy (Government contract DE-FG02-99ER62764). Thanks to Diana South, George Malloy and Cathy Smith for help with data collection, and to our volunteers for their time.

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View full text

Transcranial direct current stimulation (tDCS) produces localized and specific alterations in neurochemistry: A 1H magnetic resonance spectroscopy study

Abstract

Highlights

Section snippets

Acknowledgement

Curr. Biol.

Neurosci. Biobehav. Rev.

Eur. J. Pain

Magn. Reson. Imaging

Biol. Psychiatry

Biol. Psychiatry

Neuroimage

Neuropsychologia

Facilitation of visuo-motor learning by transcranial direct current stimulation of the motor and extrastriate visual areas in humans

Eur. J. Neurosci.

Temporal lobe cortical electrical stimulation during the encoding and retrieval phase reduces false memories

PLoS One

Rational modulation of neuronal processing with applied electric fields

Conf. Proc. IEEE Eng. Med. Biol. Soc.

Electrophysiological considerations regarding electrical stimulation of motor cortex and brain stem in humans

Neurosurgery

N-acetyl aspartate: a marker for neuronal loss or mitochondrial dysfunction

Dev. Neurosci.

Electrical stimulation of Broca's area enhances implicit learning of an artificial grammar

J. Cogn. Neurosci.

The hippocampus in patients treated with electroconvulsive therapy: a proton magnetic resonance spectroscopic imaging study

Arch. Gen. Psychiatry

The effect of clozapine on regional cerebral blood flow and brain metabolite ratios in schizophrenia: relationship with treatment response

Psychiatry Res.

Noninvasive brain stimulation improves language learning

J. Cogn. Neurosci.

Rapid modulation of GABA concentration in human sensorimotor cortex during motor learning

J. Neurophysiol.

Dynamic uncoupling and recoupling of perfusion and oxidative metabolism during focal brain activation in man

Magn. Reson. Med.

Brain polarization enhances the formation and retention of motor memories

J. Neurophysiol.

Use of tissue water as a concentration reference for proton spectroscopic imaging

Magn. Reson. Med.

Transcranial direct current stimulation (tDCS) produces localized and specific alterations in neurochemistry: A ¹H magnetic resonance spectroscopy study