Influence of stimulus intensity on odour discrimination by olfactory bulb neurons as compared with receptor cells

Previously reported electrophysiological responses recorded from individual neurons in the olfactory bulb of frogs stimulated with odorous compounds were further analyzed using statistical methods. Five of the odorants were delivered at two concentrations. The pattern of discrimination among these odorants was investigated with the aid of the Pearson's correlation test and Benzecri's ‘analyse des correspondances’. Special attention was paid to the incidence of odour concentration on this discrimination pattern. The results were compared with those of a similar study performed on receptor cells in the same experimental conditions. The comparison indicated that the information processing in the olfactory bulb seems to improve discrimination between chemically different stimuli, especially those poorly discriminated by receptor cell responses, whereas it protects this discrimination against a massive influence of the intensity of the stimuli.