Ca2+-activated K+ channels reduce network excitability, improving adaptability and energetics for transmitting and perceiving sensory information

Ca 2+ -activated K + channels (BK and SK) are ubiquitous in synaptic circuits, but their role in network adaptation and sensory perception remains largely unknown. Using electrophysiological and behavioral assays and biophysical modelling, we discover how visual information transfer in mutants lacking the BK channel (dSlo - ), SK channel (dSK - ) or both (dSK - ;;dSlo - ) is shaped in the Drosophila R1-R6 photoreceptor-LMC circuits (R-LMC-R system) through synaptic feedforward-feedback interactions and reduced R1-R6 Shaker and Shab K + conductances. This homeostatic compensation is specific for each mutant, leading to distinctive adaptive dynamics. We show how these dynamics inescapably increase the energy cost of information and distort the mutants9 motion perception, determining the true price and limits of homeostatic compensation in an in vivo genetic animal model. These results reveal why Ca 2+ -activated K + channels reduce network excitability (energetics), improving neural adaptability for transmitting and perceiving sensory information.