Spatial EEG correlates of nonassociative and associative olfactory learning in rabbits

Recent studies have shown that spatially distributed olfactory bulbar activity correlates with odor-specific behavioral responding (Coopersmith & Leon, 1984; Freeman & Grajski, 1987; Freeman & Schneider, 1982; Freeman & Viana di Prisco, 1986; Grajski, Breiman, Viana di Prisco, & Freeman, 1986; Gray, Freeman, & Skinner, 1986; Sullivan & Leon, 1986; Viana di Prisco & Freeman, 1985). The present studies established olfactory bulbar spatial electroencephalogram (EEG) correlates of nonassociative and associative learning in odorant stimulation in rabbits. Behavior was quantified by measuring magnitude and probability of the sniff response. It was shown that (a) olfactory bulbar spatial EEG amplitude patterns do not simply reflect odor (peripheral) stimulation, (b) repeated presentations of a nonreinforced odor initially reveal a transient EEG pattern change but the pattern change does not recur after the subject has habituated to the odor, and (c) repeated presentations of a reinforced odor (mild cutaneous shock), with a second nonreinforced odor serving as a control, reveal that coexisting, odor-specific spatial EEG amplitude patterns emerge with the acquisition of differential behavioral responding.