Thirty taste-responsive neurons were recorded from the cerebral cortex of 23 male Wistar rats before and after olfactory bulb stimulation for 30 sec with 50 Hz electric pulses at an intensity of 8-10 mA constant. The response of singleneurons to four basic taste stimuli was either facilitated or inhibited. The responses to HC1 tended to be attenuated by the stimulation, suggesting that, according to the labeled linenotion, capability to discriminate HCl taste becomes less accurate. After the stimulation higher correlations were found among the responses to four basic taste stimuli. This wouldmean an alteration of the across-neuron pattern activity. An important mechanism behind these changes in taste discrimination seems to be an alteration of the relative intensity between the taste responses (contrast) in a single neuron ; in 8 out of 21 neurons the contrast was accentuated between the taste responses of the second-order and the third-order, while the contrast was attenuated between the best and the 2nd-order. However, in one neuron the contrast changes between best/2nd and 2nd/3rd occurred to the opposite direction, suggesting taste discrimination that sharpening may occur as a result of stimulation.