Visual interneurons in the median protocerebrum were electrophysiologically analysed. Over half of the units responded to more than one modality (light, scent, sugar water). As the intensity dependencies for these interneurons are rather complicated, their visual properties were characterized by measuring response/intensity functions (R/I-curves). No significant response differences were found for the different recording locations in the mushroom body region. The only apparent difference was that the interneurons' spontaneous discharge frequencies differed with recording site. The visual interneurons revealed different classes of R/I-dependencies: 1. R/I curves with positive slope and a wide response range; 2. R/I curves with intensity specific response bands (I-bands); 3. R/I curves with inhibition; 4. R/I curves with little intensity dependence; 5. R/I curves with colour specific response bands. R/I curves with positive slope and a wide response range; R/I curves with intensity specific response bands (I-bands); R/I curves with inhibition; R/I curves with little intensity dependence; R/I curves with colour specific response bands. The spectral sensitivities of most units were broad. In all but one case narrow banded spectral sensitivities had a UV maximum. In many units the spectral sensitivities for the three temporal components of the response (on, sustained and off) are different. The integration of these neurons in the process of colour coding is discussed.