Download or read book The Effect of Continous Theta Burst Stimulation of Human Brain Areas MT + and V1/V2 on Color and Motion Perception written by Shaleeza Kaderali and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Although aspects of the visual image such as color, motion, form, and depth appear perceptually integrated, many are processed separately in different, specialized areas of the brain. This study investigates the differential effects of repetitive TMS (cTBS) in areas hMT+ and V1/V2 on global motion in order to reveal their roles in isoluminant chromatic compared to achromatic motion processing. Additionally, this study compares the differential effect of stimulation on motion direction versus simple detection thresholds to determine whether they have different physiological origins, since a dissociation between these two types of threshold has been established psychophysically. The report of moving or stationary phosphenes was used to localize brain areas hMT+ and V1/V2, respectively. The coil-position within each area that elicited the strongest phosphene responses was targeted for disruption by cTBS, a repetitive transcranial magnetic stimulation protocol. The vertex was used as a control for non-specific cTBS effects. Stimuli consisted of either isoluminant chromatic or achromatic random dot kinematograms (RDKs). Participants performed a motion discrimination task in which the direction of Gaussian blobs (left or right) was identified, and a simple detection task, in which the presence of a low contrast stimulus was detected regardless of motion. Thresholds were measured before and four times after cTBS stimulation within one hour to investigate the effects of cTBS on performance over time, as this has not yet been established for vision. Performances on the motion discrimination task for both achromatic and isoluminant chromatic stimuli were significantly impaired following cTBS of area hMT+. In comparison, no effect of cTBS on performance was seen for areas V1/V2 and vertex. Maximal effects occurred at 10-11 minutes after stimulation. One hour after stimulation, performance returned to baseline levels. No differential effects of cTBS between the three brain areas were observed for the detection task. This study firstly validated the use of cTBS as a tool to impair the function of area hMT+. In doing so, it provides additional evidence that area hMT+ is involved in the analysis of both achromatically as well as chromatically defined global motion. In conclusion, area hMT+ is contributing to chromatic motion seen at isoluminance. The results indicate a causal link between neural activity in area hMT+ and the perception of chromatic motion." --