72 DAVID G. MOULTON 



influence of odors on the activity which can be recorded from these various 

 sites. In this interim report the nature of this activity and attempts to 

 quantify the spike discharges of the bulb will be described. 



METHODS 



With sterile precautions, bipolar stainless steel electrodes (127/<^ and 

 63.5// in diameter) were advanced through the floor of a Incite chamber 

 attached to the skull of a young rabbit anesthetized with pentobarbital 

 sodium. When the appropriate activity was identified on the oscilloscope 

 and audio monitor the electrodes were fixed with dental cement and their 

 free ends soldered to connectors housed in the Incite container. Penicillin 

 was administered for four days following the operation. 



During trials the rabbit wore a Teflon-coated fiber-glass face mask and 

 was loosely restrained, without compression, in an open wooden box 

 inside a sound-resistant chamber. The chamber had a one-way glass 

 panel through which the behavior of the animal could be observed. Glass 

 and Teflon tubing directed a stream of air, filtered through activated carbon 

 and silica gel, into the face mask. When necessary, this stream could be 

 combined in known proportions with air saturated with a test odorant. 

 Non-olfactory stimuli included shocks delivered across the chest of the 

 animal by way of electrodes stuck to the skin, and clicks (20/sec for 5 sec) 

 delivered into a loudspeaker inside the chamber. Both stimuli were 

 generated by a Grass S4 Stimulator. To provide visual disturbance, the 

 chamber light was turned off" for 5 sec in a darkened room. Before trials 

 began, rabbits were placed individually in the experimental situation for a 

 minimum of 2 hr daily until the heart beat declined to a relatively stable 

 plateau (180-200/min). Activity from the electrodes was led through 

 preamplifiers summated on short-term averaging circuits (Beidler's integra- 

 tor), and displayed on a multichannel pen recorder. Variable electronic 

 band-pass filters were used to filter out the slow wave activity of the bulb 

 when appropriate. 



RESULTS 

 Peripheral Activity 



A variety of discharge patterns were recorded from sites in the nasal 

 mucosa but many showed little or no consistent relation to odor presenta- 

 tion. Some appeared when no stimulus was being deliberately applied by 

 the experimenter ; others were especially prominent after an animal had 

 received a shock or novel stimulus to any modality tested. These consisted 

 of prolonged trains of spike discharges up to 200/^V in amplitude. At two 

 such sites, there seemed to be a correlation with changes in the rate of 

 heart beat (Fig. 1). 



