The neurobiological mechanisms of transcranial direct current stimulation: insights from human neuroimaging and psychophysics

Hanley, Claire J. 2015. The neurobiological mechanisms of transcranial direct current stimulation: insights from human neuroimaging and psychophysics. PhD Thesis, Cardiff University. Item availability restricted.

Preview	PDF - Accepted Post-Print Version Download (4MB) | Preview
	PDF - Supplemental Material Restricted to Repository staff only Download (930kB)

Abstract

The research aimed to investigate the neurobiological basis of transcranial direct current stimulation (tDCS); a neuromodulation technique capable of inducing prolonged changes in behavioural performance. The past 15 years have seen a dramatic increase in tDCS-oriented studies, yet the underpinnings of the method are not completely understood. Consequently, this series of experiments was designed to investigate the mechanisms that contribute to the effects of the method. Focusing on neuroimaging, modulations of excitatory and inhibitory neurochemicals were assessed using Magnetic Resonance Spectroscopy (MRS); incorporating distinct spectral editing sequences to define the precise role of inhibitory neurotransmission. Additionally, concurrent DC stimulation and Magnetoencephalography (MEG) was developed, which permitted the novel investigation of excitatory and inhibitory processes via the influence of tDCS on electrophysiological responses in the motor and visual systems. This simultaneous tDCS-MEG investigation is one of only a few existing studies and was the first such endeavour by a group based in the United Kingdom. Finally, a unique psychophysical approach was adopted whereby variations of a vibrotactile adaptation task were utilised to assess the effects of tDCS on amplitude discrimination ability. The paradigms used were specifically chosen due to their physiological similarity to tDCS, thereby enabling inferences on the underpinnings of the method on the basis of changes in somatosensory task performance. These studies provided varying degrees of support for the neurobiological mechanisms proposed in the existing literature, most likely reflecting the influence of distinctions in stimulation protocols and the presence of individual difference factors thought to modify responses to stimulation. Consequently, in addition to the established insights regarding the underpinnings of tDCS, valuable perspectives on the optimisation of stimulation-based methodology were achieved by conducting the outlined investigations.

Item Type:	Thesis (PhD)
Date Type:	Publication
Status:	Unpublished
Schools:	Psychology
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Date of First Compliant Deposit:	31 May 2016
Date of Acceptance:	31 May 2016
Last Modified:	12 Jan 2017 05:20
URI:	https://orca.cardiff.ac.uk/id/eprint/91336

Actions (repository staff only)

Edit Item