To explore this idea, the activity of the astrocyte was selectively enhanced using optogenetic tools based on the specific expression of channelrhodopsin-2 (ChR2) in astrocytes24 by infection of organotypic hippocampal slices with AAVs bearing the GFAP promoter (AAV5-PGFAP-hChR2(H134R)-mCherry, Fig. 3a). The gene discussed is GFAP; the disease is infection.