Thalamocortical connectivity is enhanced following functional hemispherotomy for intractable lateralized epilepsy

Although developmental outcomes may improve following functional hemispherotomy for lateralized, catastrophic childhood epilepsy, the neuronal processes mediating these improvements are unknown. We report the case of a 14-year-old child with neurocognitive impairment who underwent functional hemispherotomy with longitudinal resting-state fMRI. Compared with preoperative fMRI, we report significantly more robust thalamo-default mode network connectivity on postoperative neuroimaging. Furthermore, we show decreased connectivity to nodes within the disconnected hemisphere, providing direct evidence that functional interactions are dependent upon structural connectivity. Since the vascular supply to these nodes remains intact, although they are disconnected from the remainder of the brain, these findings also confirm that blood-oxygen level dependent oscillations are driven primarily by neuronal activity. The current study highlights the importance of thalamocortical interactions in the understanding of neural oscillations and cognitive function, and their impairment in childhood epilepsy.