Preservation of electrophysiological functional connectivity after partial corpus callosotomy: case report

Abstract

<jats:p>Prior studies of functional connectivity following callosotomy have disagreed in the observed effects on interhemispheric functional connectivity. These connectivity studies, in multiple electrophysiological methods and functional MRI, have found conflicting reductions in connectivity or patterns resembling typical individuals. The authors examined a case of partial anterior corpus callosum connection, where pairs of bilateral electrocorticographic electrodes had been placed over homologous regions in the left and right hemispheres. They sorted electrode pairs by whether their direct corpus callosum connection had been disconnected or preserved using diffusion tensor imaging and native anatomical MRI, and they estimated functional connectivity between pairs of electrodes over homologous regions using phase-locking value. They found no significant differences in any frequency band between pairs of electrodes that had their corpus callosum connection disconnected and those that had an intact connection. The authors’ results may imply that the corpus callosum is not an obligatory mediator of connectivity between homologous sites in opposite hemispheres. This interhemispheric synchronization may also be linked to disruption of seizure activity.</jats:p>

Brain functional connectivity in individuals with callosotomy and agenesis of the corpus callosum: A systematic review

“…Other findings contradicting the thesis of a major role for the CC in ihFC have been published in a recent study examining a partial callosotomy case (Casimo et al, 2018). A patient underwent a two-stage partial callosotomy, and during the first stage a set of ECoG electrodes were implanted.…”

The structural basis for interhemispheric functional connectivity: Evidence from individuals with agenesis of the corpus callosum

“…The occurrence of bilaterally symmetric independent components in the AgCC group together with intact global functional network properties demonstrates unambiguously that interhemispheric functional integration can exist in the absence of structural connectivity ( Tyszka et al, 2011 ). Evidence from electroencephalography (EEG) studies also show that there are no significant differences in any frequency band between homologous pairs of electrodes between subjects that have undergone a corpus callostomy and those with an intact CC ( Casimo et al, 2018 ). Thus, changes in functional connectivity in AgCC may not be severe enough to be detectable by those approaches.…”

The Role of Neuroplasticity in Improving the Decision-Making Quality of Individuals With Agenesis of the Corpus Callosum: A Systematic Review

“…Although the importance of the CC on the brain’s connectivity was proven, some controversies remained because individuals who underwent partial callosotomy displayed no differences in inter-hemispheric neuronal synchronicity [ 13 ], and an acceptable explanation is the replacement’s effect on other commissures, such as the anterior, posterior, habenular, and hippocampal regions [ 4 ]. On the other hand, patients with ACC presented decision-making impairments and difficulties in solving novel problems [ 14 ] perhaps due to the remaining compromise of the associated brain regions in congenital aberrations of CC although the compensation was determined based on the anterior commissure’s width [ 9 , 15 ].…”