The study of neuronal activity with low frequency has shown an increasing interest for its greater stability and reliability recent years. One challenge in analyzing this kind of activity is to find similarities and differences between signals efficiently and effectively. The traditional analysis methods, such as short-time Fourier transform, are easily obscured by background noises and often involve a large number of parameters. Therefore, this paper introduces a novel time-frequency analysis method based on wavelet transformation and half-ellipsoid modeling to extract instantaneous frequency and instantaneous phase information. This method overcomes some shortcomings of conventional time-frequency analysis. In this method, wavelet transformation is used to provide high-level representations of raw signals, and parsimonious half-ellipsoid models are used to extract changes in time domain and frequency domain of neural recordings. The method was validated to local field potentials (LFPs) of olfactory bulb of anesthetized rats during three different odor stimuli. The results suggested that this method could detect odor-relevant features from olfactory signals with large variability. The Odors then were classified with support vector machine (SVM) algorithm and the classification accuracy reached 79.4%.
Olfactory bulb is a critical component in encoding and processing olfactory signals, characterized by its intricate neural projections and networks dedicated to this function. It has been found that descending neural projections from the olfactory cortex and other advanced brain regions can modulate the excitability of olfactory bulb output neurons in the olfactory bulb, either directly or indirectly, which can further influence olfactory discrimination, learning, and other abilities. In recent years, advancements in optogenetic technology have facilitated extensive application of neuron manipulation for studying neural circuits, thereby greatly accelerating research into olfactory mechanisms. This review summarizes the latest research progress on the regulatory effects of neural projections from the olfactory cortex, basal forebrain, raphe nucleus, and locus coeruleus on olfactory bulb function. Furthermore, the important role that photogenetic technology plays in olfactory mechanism research is evaluated. Finally, the existing problems and future development trends in current research are preliminarily proposed and explained. This review aims to provide new insights into the mechanisms underlying olfactory neural regulation as well as applications of optogenetic technology, which are crucial for advancing the research on olfactory mechanism and the application of optogenetic technology.
OBJECTIVE: To investigate the effect of olfactory ensheathing cells (OECs) on functional recovery after sciatic nerve injury. METHODS: Upon silicone-tubulization of transected sciatic nerve in 30 adult rats. Thirty rats were divided into two groups(SAL group and OECs group); saline and OECs were injected into the silicone chamber in SAL group and in OECs group respectively. The status of functional recovery of injured sciatic nerve was observed by electrophysiological analysis, axon morphometry analysis. RESULTS: In OECs group on the 30th and the 90th days after sciatic nerve transection: 1. The latent period of CMAP shortened by 0.60 ms and 0.56 ms; the nerve conduction velocity promoted by 6.42 m/s and 5.36 m/s; the amplitude enhanced by 3.92 mv and 5.84 mv, respectively; 2. The HRP positive cells in lateral nucleus of spinal anterior horn increased by 11.63% and 25.01%; 3. The number of nerve fibers increased by 1,047/mm2 and 1,422/mm2 and the thickness of myelim sheath increased by 0.43 micron and 0.63 micron, respectively. CONCLUSION: The olfactory ensheathing cells are capable of promoting the functional recovery after peripheral nerve injury.
Objective To compare their competence of olfactory epithel ial gl iacytes, olfactory globular nerve layer (OGNL) gl iacytes and SC in repair nerve defect of sciatic nerve, and select the best gl iacytes for repair of peri pheral nerve defect. Methods Olfactory epithel ial gl iacytes, OGNL gl iacytes and SC were extracted from 20 female Wistar rats aged 2-3 months and cultured in vitro for 2 weeks, then purified and condensed for transplantation. Eighty adult female Wistar rats were randomized into groups A, B, C and D (n=20). The left sciatic nerves were excised 25 mm axons and retained epineuriumlumen anastomosed to proximal ends. The culture mediums, SC, OGNL gl iacytes, and olfactory epithel ial gl iacytes weretransplanted into the epineurium lumen of groups A, B, C and D, respectively. Three months postoperatively, the injured sciatic nerve regeneration was evaluated by methods of macroscopic observation, photomicroscope, transmission electron microscope, retro-marked fluorescence transportation distance, the gl ial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) were assayed by immunofluorescence, and the myel in basic protein (MBP) and neurofilament (NF) protein were assayed by ELISA. Results The scores of ankle joint were (3.325 ± 0.963), (4.200 ± 1.005), (5.143 ± 0.635) and (5.950 ± 0.154) in groups A, B, C and D, respectively; showing statistically significant difference between groups (P lt; 0.05). The obse vations of gross, sections under microscope and transmission electron microscope showed the regeneration of defect nerve was best in group D, followed by group C, and group B was superior to group A. The transportation distance of retro-marked fluorescence was longest in group D, followed by group C, and group B was superior to group A. The concentrations of GFAP and NGF were largest in group D, followed by group C, and group B was superior to group A. The MBP concentrations were (9.817 ± 3.267), (12.347 ± 3.091), (14.937 ± 2.075) and (22.757 ± 0.871) ng/mL in groups A, B, C and D, respectively; showing statistically significant difference between other groups (P﹤0.05) except between group A and group B (P gt; 0.05). And the NF concentrations were (13.869 ± 5.677), (18.498 ± 3.889), (23.443 ± 2.260) and (27.610 ± 1.125) ng/mL in groups A, B, C and D, respectively; showing statistically significant difference between groups (P﹤0.05). Conclusion Olfactory epithel ial gl iacytes, OGNL gl iacytes and SC transplantation could repair injured nerve. The competence of olfactory epithel iums is superior to the OGNL gl iacytes andSC, and the OGNL gl iacytes is better than SC.