Neurons in the human basolateral amygdala and hippocampal formation do not respond to odors.

Extracellular action potentials were recorded from human hippocampal, hippocampal gyrus, and basolateral amygdala neurons during passive and active olfactory stimulation. Introduction of an odor into a continuous stream of air passing over the olfactory mucosa resulted in no detectable change in firing. Actively sniffing from an odorous flask, whether or not the odor was detected or recognized, also failed to elicit an immediate unit response. However, after a latency of 10-15 sec, the slight hyperventilation inherent in sniffing did induce a strong change in firing by many neurons. In contrast to these unit responses, a short-latency EEG spindle was recorded in the amygdala that appeared directly related to mechanical stimulation of the olfactory mucosa.