Changes of membrane properties and synaptic stability of rat retinal ganglion cells during postnatal development / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in the membrane properties and synaptic stability of the rat retinal ganglion cells (RGCs) during postnatal development.</p><p><b>METHODS</b>Whole-cell patch-clamp technique was used to record the action potentials (AP) and miniature excitatory postsynaptic currents (mEPSC) of SD rat RGCs at postnatal days 7, 14 and 40. The active and passive membrane properties and the synaptic stability (measured by the amplitude, frequency, rise time and decay time of mEPSC) of the RGCs were analyzed using Patchmaster software.</p><p><b>RESULTS</b>Comparison of the RGCs in SD rats across different postnatal ages revealed significant changes in the electrophysiological characteristics of the RGCs during postnatal development. The discharge rate was significantly greater while the AP half-peak width was significantly smaller at postnatal day 15 (P15) than at P7 ( < 0.01), but were both similar between P15 and P40 (=0.086); in terms of the passive membrane properties, the membrane time constant gradually decreased during the development. The frequency of mEPSCs increased significantly over time during postnatal development ( < 0.01), but was similar between P15 and P40 rats.</p><p><b>CONCLUSIONS</b>In SD rats, the membrane properties and synaptic stability of the RGCs undergo alterations following a specific pattern, which highlights a critical period where distinct changes occur in the electrophysiological characteristics of RGCs, followed by gradual stabilization over time. Such changes in the electrophysiological characteristics represent the basic characteristics of RGCs for visual signal processing, and understanding of this mechanism may provide insights into the exact role of the RGC in visual information processing.</p>

Expression and functional assessment of solute carrier 26A transporter family in HEK-293 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To express solute carrier 26A proteins in HEK-293 cells and explore their functions.</p><p><b>METHODS</b>SLC26A-eGFP plasmids were transiently transfected into HEK-293 cells, and the nonlinear capacitance of the cells expressing SLC26A proteins was measured by whole-cell patch recording.</p><p><b>RESULTS</b>All the SLC26A transporters were expressed on the membrane of HEK-293 cells. Each member of the SLC26A transporter family showed robust nonlinear capacitance, which represented their binding capability with anions.</p><p><b>CONCLUSION</b>The SLC26A transporters expressed on HEK cells show similar functions as expected in tissue environment. The plasmids we constructed facilitate structural and functional study of SLC26A transporters.</p>

A mechanical simulation model of the basilar membrane of the cochlea / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a mechanical simulation model for studying the relationship between the characteristic frequency and feature location of the basilar membrane of the cochlea.</p><p><b>METHODS</b>Macro-mechanical methods were used to simplify the details of the model. With simulation tools, the basilar membrane vibration frequency characteristics were analyzed based on the box model.</p><p><b>RESULTS</b>The basilar membrane had obvious frequency-selective properties, and the basilar membrane from the stapes was sensitive to high frequencies while the farther membrane was sensitive to low frequencies.</p><p><b>CONCLUSION</b>The frequency characteristics of the basilar membrane of the cochlea is mainly a result of the longitudinal variations of the geometric dimensions and material properties and is not related with other structures within the cochlea corti.</p>

Changes of response patterns to excitatory stimuli of different intensities: a model-based study of cochlear nucleus neurons / 南方医科大学学报

<p><b>OBJECTIVE</b>The cochlear nucleus (CN) neurons show 3 principal response patterns to short tone bursts, namely the primary-like, chopper and onset response patterns. We previously established an excitatory model to simulate the response patterns of CN neurons to stimuli. In this study, we aimed to investigate the effects of excitatory intensity on the CN neuron response patterns and explore the role of inhibitory inputs under normal physiological conditions.</p><p><b>METHODS</b>Based on the platform of Matlab and the excitatory model derived from the integrate-and-fire model, we altered the intensity of excitatory inputs in dB range and obtained the histograms to analyze the changes in the response patterns of the neurons using OriginPro 7.5 data analysis software.</p><p><b>RESULTS</b>The original primary-like response pattern of the neurons did not vary significantly while the chopper and onset response patterns changed into primary-like responses with the increase of the excitatory input intensity. But this response pattern alteration as a result of excitatory input intensity changes was rarely observed under normal physiological conditions.</p><p><b>CONCLUSIONS</b>The CN neurons receive balanced excitatory and inhibitory inputs, which stabilize the neuronal membrane potential within a limited range. The balanced inhibitory inputs decide the response pattern of a given neuron.</p>

Functional refinement of bushy cells in the anterior ventral cochlear nucleus precedes hearing onset in neonatal rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the development of the electrophysiological property of bushy cells in the anterior ventral cochlear nucleus (AVCN) of neonatal Sprague Dawley (SD) rats.</p><p><b>METHODS</b>The development of action potential and spontaneous miniature excitatory postsynaptic currents (mEPSCs) in AVCN bushy cells were investigated by whole-cell patch-clamp technique in SD rats during the postnatal days 5-21 (P5-21). The half band width of the action potential (AP), 10%-90% risetime and decay tau of the mEPSCs were analyzed.</p><p><b>RESULTS</b>The AP of the bushy cells became faster with age from P5 to P21 and stopped changing around the period of hearing onset, as evidenced by the alteration of half band width of the AP. The time accuracy of mEPSCs of the bushy cells also increased with age and stabilized around hearing onset as shown by briefer 10%-90% rise time and decay tau of mEPSCs in P14/P21 than in P7.</p><p><b>CONCLUSION</b>The functional refinement of the bushy cells in the AVCN precedes hearing onset in neonatal rats.</p>

Comparison of tonal response properties of primary auditory cortex neurons of adult rats under urethane and ketamine anesthesia / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare tonal response properties of neurons in the primary auditory cortex of Sprague-Dawley rats anesthetized with urethane and ketamine-xylazine.</p><p><b>METHODS</b>Forty-five female Sprague-Dawley rats (200-250 g) were randomized into two groups and anesthetized with urethane or ketamine-xylazine. Tone pips were chosen as the stimuli to obtain the action potentials of the single neurons by in vivo cell-attached recording. The features of the action potentials were extracted with Matlab software to comparatively analyze the acoustic response properties of the neurons between the two anesthetic groups.</p><p><b>RESULTS</b>The Q values and the characteristic frequencies were independent of the types of anesthetic agents, but with urethane anesthesia, the neurons tended to have higher minimum thresholds, lower spontaneous firing rates, longer response latencies, and more frequent occurrence of tuning with stronger inhibition compared to those in ketamine-xylazine group.</p><p><b>CONCLUSION</b>Urethane and ketamine might have no obvious impact on the transmission pathway of frequency tuning from the periphery to the auditory cortex, but neurons from rats with urethane anesthesia receive enhanced inhibition mediated by the interneurons or have a lower intrinsic excitability.</p>

Case-control study on the association between qi-stagnation and insomnia / 中西医结合学报

To investigate the relationship between insomnia and qi-stagnation by using the international standardized measurement of sleep quality and the Traditional Chinese Medicine (TCM) Constitution Scales.

Effect of propofol on first spike latency of rat inferior colliculus neurons / 中华麻醉学杂志

Objective To evaluate the effect of propofol on first spike latency (FSL) of inferior colliculus neurons and explore the electrophysiological mechanisms underlying the propofol-induced loss of heating.Methods Forty-three SD rats of both sexes weighing 200-250 g were used in this study.FSL was recorded with glass recording micro-electrode inserted in inferior colliculus.Propofol 100 mg/kg was administered intrapefitoneally.FSL was recorded before and every t0 min after propofol administration when sound intensity was between 90 dB SPL and 10 dB SPL before threshold.First-order exponential function was used to fit FSL-sound intensity curve at different time points before and after propofol administration.Results The inferior colliculus neurons showed offset response in one rat.FSL extended to 0.8 ms at 10 min after propofol administration.In the remaining 42 rats,the inferior colliculus neurons responded only to the beginning part of the sound.FSL was prolonged at 10 min after propofol administration.R2 of first-order exponential function ＞ 0.95 at different time points after propofol administration ( P ＜ 0.05 ).FSL-sound intensity curve was shifted parallelly upwards after administration.Conclusion Propofol affects auditory information transmission by extending FSL of rat inferior colliculus neurons but does not change the meaning of the information encoded by FSL.

Digital signal processing of a novel neuron discharge model stimulation strategy for cochlear implants / 南方医科大学学报

<p><b>OBJECTIVE</b>To apply the classic leakage integrate-and-fire models, based on the mechanism of the generation of physiological auditory stimulation, in the information processing coding of cochlear implants to improve the auditory result.</p><p><b>METHODS</b>The results of algorithm simulation in digital signal processor (DSP) were imported into Matlab for a comparative analysis.</p><p><b>RESULTS</b>Compared with CIS coding, the algorithm of membrane potential integrate-and-fire (MPIF) allowed more natural pulse discharge in a pseudo-random manner to better fit the physiological structures.</p><p><b>CONCLUSION</b>The MPIF algorithm can effectively solve the problem of the dynamic structure of the delivered auditory information sequence issued in the auditory center and allowed integration of the stimulating pulses and time coding to ensure the coherence and relevance of the stimulating pulse time.</p>

Design and Speech Synthesis of CIS Strategy Based on Multi-channels for Cochlear Implants Speech Signal Processing / 中国医学物理学杂志

Purpose:Cochlear implant is a sort of device which is used to restore normal heating for the profoundly deaf by electrical stimulation of the auditory nerve.Simulation of multiple channels demonstrates that the number of channels has significant influence on sound effect.Method:This paper reviews the Continuous Interleaved Sampling (CIS) strategy for cochlear implants,and simulates it in PC.The audible sound of cochlear implanter is synthesized,and preliminary analysis of the speech identification rate of CIS strategy in different channels has also been done based on the simulation.Result:CIS strategy using 6 or 8 channels can achieve better sound effect .Conclusion:Simulation results show that CIS strategy with envelope extraction and high number of channels can produce satisfactory speech synthesis effect