SPATIOTEMPORAL DYNAMICS OF ASTROGLIAL CALCIUM SIGNALS DURING SEIZURES

Astroglia play a crucial role in regulating neuronal networks and maintaining brain homeostasis. In recent years, astrogilal dysfunction has been increasingly linked to epileptic seizures. Our lab has demonstrated that perturbing astroglial glutamate transporters leads to recurrent spontaneous seizures. We have also shown that the relationship between astroglial and neuronal calcium signaling is altered before, during, and after seizures. Recent studies reveal that individual mammalian astrocytes exhibit complex spatiotemporal calcium dynamics, including centrifugal calcium waves propagating from the endfeet toward the astroglial soma. Similarly, several distinct calcium hotspots have been identified along astroglial arborizations. These findings suggest the existence of multiple types of astroglial calcium events, likely associated with different astroglial functions. In this study, we aimed to investigate the spatiotemporal dynamics of astroglial calcium signals and their relationship to astroglial function and neural excitability. By combining high-speed confocal microscopy with mosaic labeling of individual astroglial cells in zebrafish larvae, we measured calcium dynamics along individual astroglial arborizations, in vivo, during increasing levels of brain excitability and during pharmacologically induced acute seizures. Our analyses reveal that astroglial calcium activity exhibits spatially organized, nonlinear dynamics that precede and follow seizure events. These patterns differ markedly from baseline activity, suggesting an unexplored role for astrocyte networks in shaping seizure onset and propagation. We are currently mapping these glial activity patterns across brain regions and determining how pharmacological interventions modulate the spatiotemporal dynamics of astrocytic calcium, neural excitability, and seizures.