Poster Session B, Sunday, March 24, 8:00 – 10:00 am, Pacific Concourse
The Moderating Effect of White Matter Tract Integrity on Phonemic Decoding After Transcranial Magnetic Stimulation
C Nikki Arrington1,2, Sean Rogers1, Emilio Acosta1, Robin Morris1,2; 1Georgia State University, 2GSU/GT Center for Advanced Brain Imaging
Phonemic decoding (PD) is a complex skill that is facilitated by a left-lateralized reading neural network and is necessary for proficient reading. Research suggests a link between PD and white matter (WM) integrity in tracts connecting reading-related brain regions. Research also suggests that transcranial magnetic stimulation (TMS) to the supramarginal gyrus (SMG), a node of the brain’s reading network, can modulate PD. The current study examined the moderating effect of WM integrity on change in PD following TMS to the SMG. Seventeen participants (male=7; mean age=24.5) received continuous and/or intermittent theta burst stimulation to the left SMG. Pre- and post-stimulation PD was assessed using median reaction time (RT) on a forced-choice pseudoword discrimination task. Atlas-based probabilistic tractography was used to extract fractional anisotropy (FA) values for tracts associated with the reading network. Post-stimulation RT was correlated with FA in anterior portions of the corpus callosum (r = -0.38, p <0.05) and temporal portions of the superior longitudinal fasciculus (r = -0.44, p <0.05). The interaction between pre-TMS RT and FA of the corpus callosum accounted for a significant portion of the variance in post-TMS RT, R2= 0.64, F(3,9)= 5.33, p< 0.05, t= -2.72, p< 0.05. Examination of the interaction plot showed an enhancing effect such that those with higher FA and shorter pre-TMS RT showed the largest change in RT after stimulation. WM integrity may play a role in moderating the brain’s response to TMS and targeted reading outcomes.
Topic Area: LANGUAGE: Other