Altered flow of information in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is the most common form of epilepsy. However, the role of the brain's hierarchical and asymmetric flow of information in the etiology of this neurological condition remains unexplored. Here, we investigate the brain's directed functional flow of information in TLE (N = 188, TLE = 116, age = 37.73(11.86)) using transfer entropy (TE). We report that TLE is associated with two distinct patterns of the brain's flow of information: the one in which the flow of information is decreased in TLE and the other in which the flow of information is increased in TLE. Whereas the reduced flow of information in TLE is primarily right lateralized, the increased information flow in TLE is markedly interhemispheric. These interhemispheric functional pathways are primarily associated with the left hemispheric brain target regions. The first latent component of these differential patterns of the brain's flow of information correlates with the cognitive and behavioral symptoms of TLE. They include Wechsler Abbreviated Scale of Intelligence (WASI), Achenbach Adult Behavioral Checklist (AABC), Judgment of Line Orientation Raw score (JLO_R), and Heaton COWA letter fluency raw sum (FAS_R). These alterations differentiate TLE from the general population. The present study advances the previous findings in TLE by identifying asymmetrical flow of information in this condition. In so doing, it characterizes TLE with the increase in the brain's left-hemispheric flow of information. It should encourage further investigation of the brain's altered functional flow of information in TLE. This can contribute to the development of the therapeutic strategies which prioritize targeting the brain regions that play pivotal roles in its early manifestation.