Hemispheric specialization of functions are tuned by conduction velocities of neuronal propagation in large-scale brain networks

Analogous to the notion of pleiotropy where one gene can influence two or three unrelated traits, shared structural connectome encompassing both hemispheres of human brain gets functionally segregated along left vs right hemispheres during speech and melody processing, respectively. Here, the underlying neural mechanism is explored with a combined empirical and computational approach wherein, context-specific causal outflow of information emerging from primary auditory cortices (PAC) is shown to be guiding the hemispheric specialization of speech and melody processing while human volunteers listened to naturalistic music while their electroencephalogram (EEG) were recorded. Using a detailed whole-brain connectome model guided by diffusion MRI, individual-specific functional lateralization were predicted at cortical sources representing an extended auditory processing network. High levels of accuracy in prediction can be achieved after optimizing conduction velocity - controller of transmission delays of neural information processing. Thus, a tuning-by-delay mechanism is presented, which when triggered by the spectro-temporal complexity of the task context, guides the geometry of lateralization.