The Influence Of Peripheral Input And Centrifugal Modulation On The Functional Activity In Olfactory Systems

Olfactory system plays an important role in animals’ and human’s life. It is the only sensory system in the brain which projects to the cerebral cortex directly without going through the thalamus, which provides a specific model for us to study the functional activities of the brain. The functional activities in olfactory system could be effected by peripheral input and centrifugal modulation. On the one hand, olfactory system receives olfactory information input. One of the major functions of olfactory system is to reflect changes of peripheral sensory stimulation timely and accurately, while something like odor properties and locations have effects on the functional activities of olfactory system. On the other hand, olfactory system receives lots of centrifugal projections, it is possible that the functional activities of olfactory system may be influenced by the changes of centrifugal modulation. The main purpose of this thesis is to reveal how the olfactory system processes odor information when the animals are under different brain states or odor locations by using electrophysiological recording, behavior training and neural circuits tracing. The details are as follows:(1) In this study, the brain states of awake mice were altered by odor stimulation, anesthetizing and Go/No-go behavioral training, and the influence of peripheral input and centrifugal modulation on the β-band coherence of olfactory bulb (OB) and anterior piriform cortex (aPC) were analyzed. Our results demonstrate that:the β-band coherence goes up after odor stimulation; while compared with the awake mice, the β-band coherence goes down in the anesthetized ones, yet dependent on odor values in the Go/No-go trained ones. These data suggest that the β-band coherence of OB and aPC could be dynamically modulated by peripheral input and centrifugal modulation.(2) The ability of olfactory bulb to encode the binostril information is controversial. In present study, we mainly studied this issue by presenting different concentrations of contralateral odorants simultaneously with ipsilateral odor stimulation. We found that the majority of responsive neurons in the olfactory bulb respond differentially to stimuli presented on the left or the right; contralateral odorants can decrease or increase the ipsilateral response. Furthermore, the data from virus tracing showed that the ipsilateral olfactory bulb received obvious input from contralateral OB. Therefore, we reported here that the OB has potential ability to encode binostril information.