To decipher dynamic brain information processing, current genetically encoded calcium indicators (GECIs) are limited in single action potential (AP) detection speed, combinatorial spectral compatibility, and two-photon imaging depth. To address this, here, we rationally engineered a next-generation quadricolor GECI suite, XCaMPs. Single AP detection was achieved within 3–10 ms of spike onset, enabling measurements of fast-spike trains in parvalbumin (PV)-positive interneurons in the barrel cortex in vivo and recording three distinct (two inhibitory and one excitatory) ensembles during pre-motion activity in freely moving mice. In vivo paired recording of pre- and postsynaptic firing revealed spatiotemporal constraints of dendritic inhibition in layer 1 in vivo, between axons of somatostatin (SST)-positive interneurons and apical tufts dendrites of excitatory pyramidal neurons. Finally, non-invasive, subcortical imaging using red XCaMP-R uncovered somatosensation-evoked persistent activity in hippocampal CA1 neurons. Thus, the XCaMPs offer a critical enhancement of solution space in studies of complex neuronal circuit dynamics. Display omitted Display omitted •Developing XCaMPs, a spectrally resolved, quadricolor (BGYR) suite of linear GECIs•Resolving PV interneuron spike trains and non-invasive imaging of hippocampal CA1•Cell-type-specific excitation-inhibition dynamics revealed by 3-color fiber photometry•Local dendritic inhibition identified in vivo via paired axon and dendrite recording Quadricolor suite of genetically encoded calcium indicators for multiplex recording in the brain.