Intracellular responses to olfactory signals (three components and the combination of mixtures which they can provide) of 90 morphological identified local and output interneurones of the bee antennal lobe (the so-called Homo LIN, Hetero LIN, Pluri ON and Uni ON) were analysed and classified into eight main categories of response profiles. The different morphological types exhibit differences in (i) background activity; (ii) response patterns; and (iii) selectivity and responsiveness to pure odours and mixtures. The results demonstrate that the responses to mixtures are unpredictable from the responses to the single components. Olfactory integration includes inhibitory processes. Results of the present work considered together with those related to the morphological and spatial aspects demonstrate that the antennal lobe layer of the bee olfactory neuronal network is characterized by a complex architecture and connectivity underlying highly complex and somewhat unpredictable intracellular responses.