Abstract
The electrical activity of the olfactory bulb (OB) was first clearly observed around 5 days after birth in albino rats it generally consisted of (a) rhythmic “induced” waves, appearing in bursts after inspiration, and (b) “intrinsic” waves of lower amplitude and fast frequency, occurring independently of nasal air flow. The first cortical activity was also observed around the same time, and was very similar to the OB activity, especially to the induced waves. This similarity, however, diminished daily as the rats grew. In adult rats, little correspondence between the two structures was found.
A series of experiments suggested the dependence of the cortical activity upon OB induced waves because (1) the latter activity occurred with an almost fixed temporal relation to the former, (2) both cortical and OB activities were simultaneously enhanced in amplitude by (a) strong olfactory stimulation with amyl acetate or xylene as well as (b) higher doses (20 mg/kg) of pentobarbital injected intraperitoneally (i. p.), and (3) the cortical rhythmic activity, appearing in synchrony with the OB induced activity was almost completely abolished (a) when the inspired air was made to by-pass the nasal cavity and (b) after the OB was removed bilaterally.
