Functional connectivity of the motor cortex: Test-retest reliability

Studies involving functional connectivity of the brain are of growing interest due to its significance in understanding the underlying mechanisms of the resting brain and also its potential for clinical applications. This work involves examining the spatial consistency of functional connectivity within the primary motor cortex of the resting brain within and across sessions using test-retest methodology. Seven subjects underwent three resting state scans in each of three separate sessions for a total of nine resting state scans. In each of the sessions a functional MRI involving the motor cortex was also obtained. A generalized linear model (GLM) was used to extract voxels that were significantly correlated with the task from the functional MRI scan. The most strongly correlated voxels were used as seed voxels to generate functional connectivity maps from the resting state scans using GLM analysis.;We evaluated the spatial consistency of the functional connectivity maps in the motor cortex both within and across sessions using reproducibility indices. We also assessed the effect of physiological noise on the reproducibility of these indices by detecting and filtering the physiological noise using two methods: spatial ICA and an established method called RETROICOR. Results indicate that the resting state network, at least in the case of the motor cortex, is quite reliable both within and across sessions. Further, from our results it appears that the reliability of these networks is not influenced by the physiological noise.