Odor-driven activity in the olfactory cortex of an in vitro isolated guinea pig whole brain with olfactory epithelium.
We developed a new technique to isolate a whole guinea pig brain with an intact olfactory epithelium (OE) that enables us to access the ventral surface of the brain including olfactory areas with ease during natural odor stimulation. We applied odorants to OE and confirmed that odor-induced local field potentials (LFPs) could be induced in olfactory areas. In the olfactory bulb (OB) and the piriform cortex (PC), odor-induced LFPs consisted of a phasic initial component followed by a fast activity oscillation in the beta range (20 Hz). To understand the neural mechanisms of odor-induced responses especially in the anterior PC, we analyzed odor-induced LFPs, together with unit activity data. We confirmed that the initial component of odor-induced response has a characteristic temporal pattern, generated by a relatively weak direct afferent input, followed by an intra-cortical associative response, which was associated with a phasic inhibition. The beta oscillation might be formed by the repetition of these network activities. These electrophysiological data were consistent with the results of previous studies that used slice or in vivo preparations, suggesting that the olfactory neural network and activities of the brain are preserved in our new in vitro preparation. This study provides the basis for clarifying the sequence of neural activities underlying odor information processing in the brain in vitro following natural olfactory stimulation.
Ishikawa
Takahiro
T
Division of Systems Neuroscience, Tohoku University Graduate School of Life Sciences, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Sato
Takaaki
T
Shimizu
Akira
A
Tsutsui
Ken-Ichiro
K
de Curtis
Marco
M
Iijima
Toshio
T
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004210:Dissection / Q000295:instrumentation / Q000379:methods; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D006168:Guinea Pigs; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D009812:Odorants; D009830:Olfactory Bulb / Q000502:physiology*; D009831:Olfactory Mucosa / Q000502:physiology*; D009832:Olfactory Nerve / Q000502:physiology; D009833:Olfactory Pathways / Q000502:physiology*; D009924:Organ Culture Techniques / Q000295:instrumentation / Q000379:methods; D012903:Smell / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology