Multimodal integration facilitates object recognition and response to sensory cues. This depends on spatio-temporal coincidence of sensory information, recruitment of NMDA-type glutamate receptors and inhibitory feedback. Shepherd's crook neurons in the avian optic tectum are an ideal model for studying cellular mechanism of multimodal integration. They receive different sensory modalities through spatially segregated dendrites, are important for stimulus selection and have an axon-carrying dendrite. We performed whole-cell patch-clamp experiments in chicken midbrain slices of both sexes. We emulated visual and auditory input in vitro by stimulating presynaptic afferents electrically. Simultaneous stimulation enhanced responses inversely depending on stimulation amplitude demonstrating the principle of inverse effectiveness. Contribution of NMDA-type glutamate receptors prolonged postsynaptic events for visual inputs only, causing a strong modality-specific difference in synaptic efficacy. We designed a mu...