Figure 2.

illustrates simultaneous recordings two poles of an electrode array located in the superficial layers of the lateral part of the olfactory bulb and the data analysis. Electrode arrays (A) were driven into the dorsal and lateral aspects of the bulb (B) until multiunit responses were found to several of the odorants in the sample series. Only rarely were apparent mitral cells (judged by spike size and response pattern in this case) encountered. All points where the voltage records crossed the value 1.5 standard deviations ± the mean voltage (thin lines) in the one second interval before stimulation were marked. These were low-pass filtered with a function that decayed to half maximum in 50 msec to give a record like the ones shown above in black. Note that large spikes are not weighted more than small spikes. Even though these two adjacent traces had different spikes, the summed records were very similar. The heavy bars under the traces show the two odor pulses used in this recording. This figure illustrates the response to a pair of odor pulses to make the odor response more obvious, although the subsequent figures show responses to longer, single odor pulses.