Title: Large-scale Brain Dynamical Mechanisms for Absence Seizures
Time: 10:00 a.m. Friday April 19, 2019
Location: Conference Room 4022 Gezhi Building
Absence epilepsy is characterized by a sudden paroxysmal loss of consciousness accompanied by oscillatory activity propagating over many brain areas. A physiologically based corticothalamic model of large-scale brain activity is used to analyze critical dynamics of transitions from normal arousal states to epileptic seizures, which correspond to Hopf bifurcations. This relates an abstract normal form quantitatively to the main underlying physiologies that includes neural dynamics, axonal propagation, and time delays. Thus, a bridge is constructed that enables normal forms to be used to interpret quantitative data. This model is further investigated with focal spatial heterogeneity, numerically and analytically. An emergent spatiotemporal dynamic is found for seizure localization, whose spatiotemporal properties are comparable with experimental observations, providing a new biophysical explanation of the temporally higher frequency, but spatially more localized cortical waves observed in genetic rodents that display characteristics of human absence epilepsy, from the perspective of large-scale brain dynamics. Predictions are also presented for further experimental test. Thus, we propose a dynamical mechanism to unify the global and focal aspects of absence epilepsy with focal absence seizures associated with localized seizures, and the global ones associated with generalized seizures. More details of cellular nonlinear dynamics or heterogeneous connectivity can be further introduced into the large-scale Physical brain system for future studies.
