Application of non-invasive brain stimulation in psychophysiology

INTRODUCTION In the past, much of the research in traditional experimental psychology came down to performance measures, usually differences in accuracy and reaction time, and this paucity of measures often led to the inability to choose between competing theories. The promise of psychophysiological experimentation on humans lay in the extra measures it provided, opening a window to the mind by examining brain response. The drawback lay in the fact that the physiological evidence discovered was correlative: measured changes in brain activity could only suggest psychological relationships. The development of sophisticated brain imaging techniques and high density EEG only magnified this problem. The application of non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) offer a way of designing psychophysiological experiments that produce causal evidence linking brain with behavior (Silvanto & Pascual-Leone, 2012). Brain stimulation involves the introduction of electromagnetic fields to modulate electrical activity in the brain. For example, TMS involves the use of brief magnetic pulses to induce current flow in cortical tissue near the surface of the head, stimulating neurons in a focal region and affecting ongoing cortical activity, while tDCS modulates neuronal transmembrane potentials during stimulation. Actively affecting cortical processing in this way, within the context of behavioral experimentation and brain imaging, allows causal relationships to be established and explored. These two forms of brain stimulation are the most commonly used, and in this chapter, after a brief overview of their history, the physical and physiological principles behind their use, as well as their various effects, will be discussed in the second section, followed by a section on experimental methods, involving safety, targeting, measurement of effects, and experimental design. THE HISTORICAL CONTEXT FOR PSYCHOLOGICAL INTEREST IN tDCS AND TMS The basic design of tDCS has existed for well over 200 years, as a direct result of the scientific contributions of Galvani and Volta in the 1790s in bioelectromagnetics and electrophysiology. In 1801, Giovanni Aldini, who was the nephew of Galvani, successfully applied galvanic electrical stimulation to treat a patient with melancholy (Parent, 2004). With the introduction of electroconvulsive therapy by Ugo Cerletti and Lucio Bini in 1938, interest in using weak electric currents to modulate brain activity waned for several decades.

Duke Scholars

Author Zhi-de Deng Psychiatry & Behavioral Sciences, Behavioral Medicine & Neur ...