Prefrontal transcranial direct current stimulation (tDCS) changes negative symptoms and functional connectivity MRI (fcMRI) in a single case of treatment-resistant schizophrenia

hand contraction evoked from a TMS pulse over motor cortex is inhibited when proceeded by a conditioning pulse in the opposite hemisphere. IHI is also believed to be mediated by the corpus callosum and has been previously related to IHI (Wahl et al., 2007). Older adults have previously been found to have decreases in long (40 ms interpulse interval) but not short (10 ms) IHI and under conditions related to the contraction state of the muscle (Talelli et al., 2008). Methods: Resting state FC, resting muscle IHI, and diffusion tensor imaging (DTI) were collected in 16 older adults. IHI was measured with the right motor cortex (left hand) as the target. DTI was analyzed by placing a seed voxel in the motor hand area (based on structural MRI) and performing tractography projecting to the callosum and measuring fractional anisotropy. Long IHI was correlated with FC and it was also correlated with FA. Results: Older adults demonstrated a significant correlation between long, IHI and FC (r = 0.53, p < .05). There was also a correlation between long IHI and FA but this only significant with a unidirectional test in the expected direction such that higher FA was associated with stronger IHI (r = 0.44, p < .05). Conclusions: Resting IHI is related to resting state FC and callosum integrity in older adults. Implications for the HAROLD model and stroke-related functional compensation will be discussed.