42 



D. OTTOSON 



be segregated under various experimental conditions. Thus it has been 

 demonstrated that the first component builds up a persisting potential 

 during repetitive stimulation (Fig. 8), whereas the second component is 



• 



Fig. 8. Summation of the initial phase of the bulb response. Repetitive stimula- 

 tion : A, 10 ; B, 15 ; C, 20 ; D, 50/sec. Vertical bar 1 mV. Time mark 

 200 msec. (From Ottoson, 1959c.) 



unable to follow stimulation frequencies above 1 per sec without being 

 considerably reduced in height. In has therefore been concluded that the 

 first component is of synaptic origin, while the second one seems to reflect 

 the activity in the secondary pathways. If this view is correct the first 

 component would correspond to the slow potential of the bulbar response 

 evoked by natural stimulation, while the second component would be 



Fig. 9. Structural organization of the olfactory bulb. (From Van Gehuchten 



and Martin, 1891.) 



