Excitability changes in the visual cortex quantified with signal detection analysis

• Published in: Restorative neurology and neuroscience Vol. 29; no. 6; pp. 453 - 461
• Main Authors: Olma, Manuel C., Kraft, Antje, Roehmel, Jasper, Irlbacher, Kerstin, Brandt, Stephan A.
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.01.2011
• Subjects: Adult; Analysis of Variance; Brain Mapping; Electrodes; Female; Humans; Magnetic Resonance Imaging; Male; Photic Stimulation; Psychophysics; Reaction Time - physiology; Signal Detection, Psychological; Transcranial Magnetic Stimulation - methods; Visual Cortex - physiology; Young Adult; neuromodulation; signal detection theory; visual cortex; Transcranial direct current stimulation (tDCS); visual psychophysical performance
• ISSN: 0922-6028; 1878-3627; 1878-3627
• DOI: 10.3233/RNN-2011-0607

Purpose: TDCS can increase excitability in the visual cortex. It is a matter of current debate if tDCS can improve visual performance. Promising parameters to measure detection sensitivity may be those of the signal detection theory ( = SDT), as it allows differentiating between response bias and detection sensitivity changes. The measure of detection sensitivity can be used to predict actual performance under a wide variety of different response criteria. Methods: Here we test if the SDT can quantify tDCS-induced effects in a visual contrast discrimination task in healthy subjects. Results: Anodal stimulation of the visual cortex improved performance, as calculated by detection sensitivity for stimuli presented in the center of the visual field. More peripheral locations in the visual field were unaffected by anodal stimulation. Cathodal stimulation and sham stimulation of the visual cortex had no consistent effect on detection sensitivity. The response bias was not affected by any type of stimulation. Conclusions: Neuroplastic changes in the visual cortex induced by anodal tDCS can be measured by SDT, suggesting SDT could prospectively be a useful approach for monitoring restorative tDCS-effects on visual function in patients with central visual deficits.