The stomatogastric ganglion (STG) of shellfish includes 30 neurons and produces pyloric rhythms. It is the common model to study central pattern generator (CPG). Regulation of pyloric rhythms not only is related to the property of single neurons in STG but also depends on the connections and property of the whole neuronal network. It has been found that transient potassium current (I(A)) and hyperpolarization-activated cation current (I(h)) exist in certain types of neurons of STG. However, roles played by these two currents in maintaining and regulating the pyloric rhythms are unknown. In the present study, in vitro electrophysiological recordings were performed on crayfish STG to examine the role played by I(A) and I(h) in regulation of pyloric rhythm. 4AP (2 mmol/L), a specific inhibitor of I(A), caused a decrease in pyloric cycle (P < 0.01), an increase in PD (pyloric dilator) ratio, a decrease in PY (pyloric) ratio (P < 0.01) and delay of phases of LP and PY firing. ZD7288 (100 μmol/L), a specific inhibitor of I(h), caused a decrease in pyloric cycle (P < 0.01), an increase in PD ratio (P < 0.01), an increase in LP (lateral pyloric) ratio (P < 0.01), a decrease in PY ratio (P < 0.01) and delay of phases of LP and PY firing. These results indicate that I(A) and I(h) play important roles in regulating pyloric rhythms in crayfish STG.
Animals ; Astacoidea ; cytology ; Ganglia, Invertebrate ; physiology ; Neurons ; cytology ; Pylorus ; innervation

In central nervous system only a limited number of vesicles exist in the presynaptic terminals. The size and fusion modes of the vesicles were particularly important because of their potential impact on neuronal communications. Efficient methods were needed to analyze the recycling kinetics of synaptic vesicle and the size of readily releasable pool (RRP). In this study, fluorescent dyes with different affinity for membranes (FM1-43 with high affinity and FM2-10 with low affinity) were used to stain the functional synaptic vesicles of cultured hippocampal neurons and the kinetics of vesicle recycling was measured. The results showed that the destaining proportion was larger for FM2-10 than that for FM1-43 during the first trial, while it was greater for FM1-43 than FM2-10 during the second and third trials (first round, 93.0%+/-5.9% versus 57.9%+/-3.5% for FM2-10 and FM1-43, respectively, P<0.0001; second round, 1.4%+/-3.8% versus 24.0%+/-2.3%, P<0.0001; third round, 2.3%+/-1.6% versus 8.6%+/-1.5%, P=0.005). The results indicated that rapid endocytosis existed not only in the first round but also occurred when the vesicles were reused. Moreover, Both high-frequency stimuli and hypertonic sucrose stimuli were used to estimate the RRP sizes in the mix cultured hippocampal inhibitory neurons at 13-14 days in vitro (DIV). We found that the RRP size estimated by hypertonic sucrose stimuli [(200+/-23.0) pC] was much larger than that estimated by high-frequency stimuli [(51.1+/-10.5) pC]. One possible reason for the discrepancies in RRP estimates is that in mix cultured conditions, one neuron may receive inputs from several neurons and hypertonic sucrose stimuli will cause RRP of all those neurons release, while using dual patch recording, only the connection between two neurons was analyzed. Thus, to exclude out the impacts of inputs numbers on RRP sizes, it is more reasonable to use high-frequency stimuli to estimate the RRP size in mix cultured neurons.
Cells, Cultured ; Endocytosis ; Hippocampus ; cytology ; Neurons ; physiology ; Synaptic Vesicles ; physiology

External tufted (ET) cells are the major excitatory elements coordinating the activities of glomerulars and mediating the input from the olfactory neurons to mitral cells. The ET cells participate in inter-and intra-glomerular microcircuits in the olfactory bulb, link the isofunctional odor columns within the same olfactory bulb, and play an important role in olfactory information processing. This paper reviews the research progress of the anatomy and physiological properties and electrophysiological modeling of ET cells, elaborate the problems and defects in the field. And then it further gives some proposals for the future research of electrophysiological properties, development of olfactory information coding and performance of modeling of ET cells.
Electrophysiological Phenomena ; physiology ; Humans ; Olfactory Bulb ; cytology ; physiology ; Olfactory Pathways ; physiology ; Olfactory Receptor Neurons ; cytology

In natural acoustical environments, most biologically related sounds containing frequency-modulated (FM) components repeat over periods of time. They are often in rapid sequence rather than in temporal isolation. Few studies examined the neuronal response patterns evoked by FM stimuli at different presentation rates (PR). In the present investigation, by using normal electrophysiological technique, we specifically studied the temporal features of response of the inferior collicular (IC) neurons to FM sweeps with different modulation ranges (MR) in conditions of distinct PR in mouse. The results showed that most of the recorded neurons responded best to narrower MRs (narrow-pass, up-sweep: 60.00%, 54/90; down-sweep: 63.33%, 57/90), while a small fraction of neurons displayed other patterns such as band-pass (up-sweep, 16.67%, 15/90; down-sweep, 18.89%, 17/90), all-pass (up-sweep, 18.89%, 17/90; down-sweep, 13.33%, 12/90) and wide-pass (up-sweep, 4.44%, 4/90; down-sweep, 4.44%, 4/90). Both the discharge rate and duration of recorded neurons decreased but the latency lengthened with increase in PR, when different PRs from 0.5/s to 10/s of FM sound were used. The percentage of total directional selective neurons, up-directional selective neurons, and down-directional selective neurons changed with the variation of PR or MR. These results indicate that temporal features of mouse midbrain neurons responding to FM sweeps are co-shaped by the MR and PR. Possible mechanisms underlying may be related to spectral and temporal integration of the FM sound by the IC neurons.
Acoustic Stimulation ; Animals ; Inferior Colliculi ; cytology ; Mice ; Neurons ; physiology

Both animal communication sounds and human speech contain frequency-modulated (FM) sweeps. Although the selectivity for the rate of FM sweeps in neurons has been found in many kinds of animals at different levels of the central auditory structures, the underlying neural mechanism is still not clear. Using extracellular single unit recording techniques, we examined the selectivity for the rate of FM sweeps in the inferior colliculus (IC) neurons of the Kunming mouse (Mus musculus, Km) in the free-field stimulation conditions and determined its affecting factors. Totally, 102 neurons were recorded successfully, among which 42 neurons (41.2%) displayed a duration tuning pattern under pure tone (PT) stimulus. The percentages of short-pass, band-pass, and long-pass neurons were 22.6% (23/10), 8.8% (9/102), 9.8% (10/102), respectively. The other 60 neurons (58.8%) did not show any duration tuning features. Under FM stimulus, the majority of duration tuning neurons (78.6%, 33/42) showed the selectivity for the rate of FM sweeps. For these neurons, the type of rate selectivity was determined by the duration tuning features, but it was not related to the modulation range (MR) of FM. In a small fraction of duration tuning neurons (21.4%, 9/42), the rate selectivity was correlated with the MR, but uncorrelated with the duration tuning features. On the other hand, more than half of the non-duration tuning neurons (53.3%, 32/60) exhibited the rate selectivity under FM stimulus, and almost all of them (31/32) showed fast-rate selectivity. Nevertheless, there were 8 neurons (in 32) displaying the same best rate at different MR, indicating that they were real rate-selective neurons. Our results indicate that the selectivity for the rate of FM sweeps is co-determined by duration tuning features and sweep bandwidth. Only a few of inferior colliculus neurons belong to real rate-selectivity neurons in the mouse.
Acoustic Stimulation ; Animals ; Inferior Colliculi ; cytology ; Mice ; Neurons ; physiology

To investigate the intracellular mechanism of activity-dependent synapses formation and redistribution, we studied the electrophysiological and morphological characteristics of neurons of the developing visual cortex, and observed the level of synchronism of age and changes in the properties. Whole cell patch-clamp recordings and intracellular biocytin staining were used to record postsynaptic currents (PSCs) from neurons in the visual cortex of Sprague-Dawley rats (postnatal d 4-28). The histological processing was made. There were three types of PSCs in 156 cells: silent response, monosynaptic response and polysynaptic response, during the first developmental month. Before eyes opened the number of the neurons with the silent response (57.3%) was significantly higher than that after the eyes opened (11.9%) (P<0.001). However, the incidence of polysynaptic PSCs increased from 12.4% before eyes opened to 28.9% after eyes opened (P<0.01). During postnatal week 1, all cells were classified as immature. The immature cells had very high input resistances (R(N)>1.0 G Omega), low amplitude (-0.87 mA) and short decay time (-0.98 ms). During postnatal week 4, all cells were mature with lower input resistance (R(N)<310 M Omega), larger amplitude (-66 mA), and longer decay time (-225 ms). From postnatal weeks 1 to 3, the cells had electrophysiological properties that were intermediate between the immature and mature types of cells. With biocytin intracellular staining, five types of neurons were obtained: pyramidal cells, satellite cells, basket cells, neuroglial cells and immature cells. On the basis of their electrophysiological and morphological characteristics, pyramidal cells were classified into three categories: immature, intermediate, and mature cell types. During postnatal week 1, cells were immature with very high input resistance. Morphologically immature cells had short simple dendritic arborizations which incompletely penetrated the layer where the cell body lies. From postnatal weeks 2 to 4, the cells were mature with low input resistance. They were morphologically more complex with dendritic arborizations which completely penetrated the whole layers of the visual cortex. From postnatal weeks 1 to 2, a third, intermediate cell type had electrophysiological properties that were intermediate between the immature and mature cell types. Three distinctive types of pyramidal cells in visual cortex only co-exist during postnatal weeks 1 to 2. Data show that activity-dependent synapes are formed and integrated into local neuronal networks with visual stimulation. In the critical period of visual development, the level of synchronism of age and changes in electrophysiological and morphological properties in the visual cortex is higher than that in the subcortex.
Animals ; Animals, Newborn ; Excitatory Postsynaptic Potentials ; physiology ; Neurons ; cytology ; physiology ; Pyramidal Cells ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley ; Synapses ; metabolism ; physiology ; Visual Cortex ; cytology ; growth & development ; physiology

The purpose of this study was to investigate the influence of electrical stimulation of anterior cingulate cortex (ACC) on spontaneous activity of neurons in thalamic ventrobasal nucleus (VB). Experiments were performed on 12 male Sprague-Dawley rats weighing 250-310 g (4-5 months old). According to Paxinos and Watson's coordinate atlas of the rat, the frontal and parietal cortical areas were exposed by craniotomy, the recording electrodes were then inserted into the VB (P 2.4-4.1 mm, R 2.0-3.5 mm, H 5.2-6.8 mm) and the stimulating electrodes into the ACC (A 1.1-3.0 mm, R 0.0-1.0 mm, H 1.5-2.4 mm). Single-unit activities were recorded extracellularly in the VB by glass micropipettes (impedance 3-8 MOmega) filled with 0.5 mol/L sodium acetate solution containing saturated Fast Green. To study the effects of ACC activation on the spontaneous activities of VB cells, single electrical pulse (0.2 ms duration) was delivered to the ACC by a concentric bipolar stainless steel electrode (0.32 mm outer diameter). An effective ACC stimulation was determined for each VB neuron by gradually increasing the current intensity from 0.1 mA until either a significant change in the spontaneous activity of the VB neuron was observed, or the current intensity reached 0.4 mA. The results showed that ACC stimulation significantly suppressed the spontaneous activities in 12 out of 53 VB neurons (22.6%). (1) After the stimulation was delivered to ACC, the spontaneous activities of different VB neurons were totally suppressed for different time span. (2) There was obvious dose-effect relevance between ACC stimulation intensity and their inhibitory effect. The duration of complete inhibition was prolonged with the increases in the intensity and number of stimulation impulses in ACC. (3) The stimulation in the ACC depressed the spontaneous activities of VB neurons in different forms and this inhibition exhibited an accumulative effect. All these results indicate that the stimulation of ACC exerts an inhibitory influence on the spontaneous activities of VB neurons.
Animals ; Electric Stimulation ; Gyrus Cinguli ; physiology ; Male ; Neurons ; cytology ; Rats ; Rats, Sprague-Dawley ; Thalamic Nuclei ; cytology

OBJECTIVE: To demonstrate the spatial organization of neurons, astrocytes and vessels in rat brain. METHODS: Cerebral vascular was shown by vivi-perfusion with ink. Glial fibrillary acidic protein (GFAP) immunohistochemistry and nissl's staining were performed on the serial sections of frozen brain tissues. RESULTS: Astracytes distributed along the branches of blood vessels, and neurons in the region of the relatively rich blood vessels. Neurons and astrocytes presented regional distribution. CONCLUSION This method can well indicate the spatial organization of neurovascular unit, the regional differences in the distribution may be related to physical activities and the corresponding adjustment function.
Animals ; Astrocytes ; cytology ; physiology ; Brain ; cytology ; physiology ; Cerebrovascular Circulation ; physiology ; Female ; Glial Fibrillary Acidic Protein ; biosynthesis ; Male ; Neurons ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley

The purpose of this research is to investigate the critical period of voltage-gated Na(+) channel development in hippocampal CA1 neurons. Changes of Na(+) currents in acutely isolated hippocampal CA1 neurons of rats at different ages (0-4 weeks after birth) were recorded using the whole-cell patch-clamp technique. The results indicated that the maximum current density of Na(+) channels was increasing with age, and the amplitudes in 1, 2, 3 and 4 weeks respectively grew by (42.76 ± 4.91)%, (146.80 ± 7.63)%, (208.79 ± 5.28)% and (253.72 ± 5.74)% (n = 10, P < 0.05) compared with that in 0 week. The current density in CA1 neurons of 1-2 weeks after birth increased more significantly than those of other groups. The activation curve of Na(+) channel shifted to the left. The half-activation voltages (mV) in 0-2 weeks were -39.06 ± 0.65, -43.41 ± 0.52, -48.29 ± 0.45 (n = 10, P < 0.05), respectively, showing significant age-dependent decrease, and there were no significant changes in other groups. The slope factors of activation curve for each group did not change significantly. There were no regular changes in inactivation curve and no significant changes in half-inactivation voltage. The slope factors of inactivation curve in 1-2 weeks were: 5.77 ± 0.56, 4.42 ± 0.43 (n = 10, P < 0.05). The inactivation rate of the second week after birth was faster than that of the first week, and there were no significant changes during 0-1 week and 2-4 weeks. The recovery from inactivation curve of Na(+) channel shifted to the left. The recovery time declined in 1-3 weeks. Changes of action potential properties were consistent with Na(+) current. These results suggest that the period of 1-2 weeks after birth may be the critical development period of voltage-gated Na(+) channel in hippocampal CA1 neurons. During this time, the distribution of Na(+) channel increases significantly; the activation curve of Na(+) channel shifts to the left; inactivation rate increases as well as recovery time shortens.
Action Potentials ; Animals ; CA1 Region, Hippocampal ; cytology ; Neurons ; physiology ; Patch-Clamp Techniques ; Rats ; Sodium Channels ; physiology

Using conventional electrophysiological technique, we investigated the effects of stimulating the medial prefrontal cortex (mPFC) on plasticity of frequency receptive field (RF) in auditory cortical (AC) neurons in rats. When the mPFC was electrically stimulated, the RF plasticity of 51 (27.2%) neurons was not affected and that of 137 neurons (72.8%) was either inhibited (71 neurons, 37.7%) or facilitated (66 neurons, 35.1%). The modulation of RF plasticity by the stimulation of mPFC was dependent upon the time interval between acoustic and electrical stimuli. The best interval time that produced optimal modulation (inhibition or facilitation) ranged from 5 to 30 ms. The inhibitory modulation of mPFC prolonged RF shifting time and shortened RF recovery time. Conversely, the facilitatory modulation of mPFC shortened RF shifting time and prolonged RF recovery time. Our results suggest that the mPFC may affect the plasticity of functional activity in AC neurons, and also may participate in the process of auditory learning and memory.
Animals ; Auditory Cortex ; cytology ; Electric Stimulation ; Neuronal Plasticity ; Neurons ; physiology ; Prefrontal Cortex ; physiology ; Rats