With inherent sparse spike-based coding and asynchronous event-driven computation, spiking neural network (SNN) is naturally suitable for processing event stream data of event cameras. In order to improve the feature extraction and classification performance of bio-inspired hierarchical SNNs, in this paper an event camera object recognition system based on biological synaptic plasticity is proposed. In our system input event streams were firstly segmented adaptively using spiking neuron potential to improve computational efficiency of the system. Multi-layer feature learning and classification are implemented by our bio-inspired hierarchical SNN with synaptic plasticity. After Gabor filter-based event-driven convolution layer which extracted primary visual features of event streams, we used a feature learning layer with unsupervised spiking timing dependent plasticity (STDP) rule to help the network extract frequent salient features, and a feature learning layer with reward-modulated STDP rule to help the network learn diagnostic features. The classification accuracies of the network proposed in this paper on the four benchmark event stream datasets were better than the existing bio-inspired hierarchical SNNs. Moreover, our method showed good classification ability for short event stream input data, and was robust to input event stream noise. The results show that our method can improve the feature extraction and classification performance of this kind of SNNs for event camera object recognition.
Visual Perception ; Learning ; Action Potentials ; Neural Networks, Computer ; Neuronal Plasticity

Electromagnetic stimulation is an important neuromodulation technique that modulates the electrical activity of neurons and affects cortical excitability for the purpose of modulating the nervous system. The phenomenon of inverse stochastic resonance is a response mechanism of the biological nervous system to external signals and plays an important role in the signal processing of the nervous system. In this paper, a small-world neural network with electrical synaptic connections was constructed, and the inverse stochastic resonance of the small-world neural network under electromagnetic stimulation was investigated by analyzing the dynamics of the neural network. The results showed that: the Levy channel noise under electromagnetic stimulation could cause the occurrence of inverse stochastic resonance in small-world neural networks; the characteristic index and location parameter of the noise had significant effects on the intensity and duration of the inverse stochastic resonance in neural networks; the larger the probability of randomly adding edges and the number of nearest neighbor nodes in small-world networks, the more favorable the anti-stochastic resonance was; by adjusting the electromagnetic stimulation parameters, a dual regulation of the inverse stochastic resonance of the neural network can be achieved. The results of this study provide some theoretical support for exploring the regulation mechanism of electromagnetic nerve stimulation technology and the signal processing mechanism of nervous system.
Action Potentials/physiology* ; Computer Simulation ; Models, Neurological ; Stochastic Processes ; Neurons/physiology* ; Electromagnetic Phenomena

Neurons/physiology* ; Action Potentials/physiology*

Objective: To investigate the application of cochlear nerve action potential (CNAP) monitoring in the resection of vestibular schwannoma, especially evaluating its significance for hearing preservation. Methods: From April 2018 to December 2021, 54 patients with vestibular schwannoma who underwent resection via retrosigmoid approach were collected in Chinese PLA General Hospital. Before surgery, all patients had effective hearing (AAO-HNS grade C or above). Brainstem auditory evoked potential (BAEP) combined with CNAP monitoring was performed during surgery. The CNAP monitoring was combined with continuous monitoring and cochlear nerve mapping. And patients were divided into hearing preservation group and non-preserved group according to postoperative AAO-HNS grade. SPSS 23.0 software was used to analyze the differences of CNAP and BEAP parameters between the two groups. Results: A total of 54 patients completed intraoperative monitoring and data collection, including 25 males (46.3%) and 29 females (53.7%), aged 27-71 years with an average age of 46.2 years. The maximum tumor diameter were (18.1±5.9) mm (range 10-34 mm). All tumors were totally removed with preserved facial nerve function (House-Brackmann grade I-II). The hearing preservation rate of 54 patients was 51.9% (28/54). During surgery, the V wave extraction rate of BAEP waveform was 85.2% (46/54) before tumor resection, 71.4% (20/28) in the hearing preservation group after tumor resection, and disappeared in the hearing preservation group (0/26). CNAP waveform was elicited in 54 patients during operation. Differences were found in the distribution of CNAP waveforms after tumor resection. The waveforms of the hearing-preserving group were triphasic and biphasic, while those in the non-preserving group were low-level and positive. For hearing preservation group, the amplitude of N1 wave after tumor resection was significantly higher than that before tumor resection[14.45(7.54, 33.85)μV vs 9.13(4.88, 23.35)μV, P=0.022]; However, for the non-preserved group, the amplitude of N1 wave after tumor resection was significantly lower than that before tumor resection [3.07(1.96, 4.60)μV vs 6.55(4.54, 9.71)μV, P=0.007]; After tumor resection, the amplitude was significantly higher than that of the unreserved group [14.45(7.54, 33.85)μV vs 3.07(1.96, 4.60)μV, P<0.001]. Conclusions: BAEP combined with CNAP monitoring is conducive to intraoperative hearing protection, and the application of cochlear nerve mapping can prompt the surgeon to avoid nerve injury. The waveform and N1 amplitude of CNAP after tumor resection have a certain value in predicting postoperative hearing preservation status.
Female ; Male ; Humans ; Middle Aged ; Neuroma, Acoustic/surgery* ; Action Potentials ; Evoked Potentials, Auditory, Brain Stem ; Cochlea ; Cochlear Nerve

Differing from other subtypes of inhibitory interneuron, chandelier or axo-axonic cells form depolarizing GABAergic synapses exclusively onto the axon initial segment (AIS) of targeted pyramidal cells (PCs). However, the debate whether these AIS-GABAergic inputs produce excitation or inhibition in neuronal processing is not resolved. Using realistic NEURON modeling and electrophysiological recording of cortical layer-5 PCs, we quantitatively demonstrate that the onset-timing of AIS-GABAergic input, relative to dendritic excitatory glutamatergic inputs, determines its bi-directional regulation of the efficacy of synaptic integration and spike generation in a PC. More specifically, AIS-GABAergic inputs promote the boosting effect of voltage-activated Na⁺ channels on summed synaptic excitation when they precede glutamatergic inputs by >15 ms, while for nearly concurrent excitatory inputs, they primarily produce a shunting inhibition at the AIS. Thus, our findings offer an integrative mechanism by which AIS-targeting interneurons exert sophisticated regulation of the input-output function in targeted PCs.
Axon Initial Segment ; Axons/physiology* ; Neurons ; Synapses/physiology* ; Pyramidal Cells/physiology* ; Interneurons/physiology* ; Action Potentials/physiology*

The family of voltage-gated potassium Kv2 channels consists of the Kv2.1 and Kv2.2 subtypes. Kv2.1 is constitutively highly phosphorylated in neurons and its function relies on its phosphorylation state. Whether the function of Kv2.2 is also dependent on its phosphorylation state remains unknown. Here, we investigated whether Kv2.2 channels can be phosphorylated by protein kinase C (PKC) and examined the effects of PKC-induced phosphorylation on their activity and function. Activation of PKC inhibited Kv2.2 currents and altered their steady-state activation in HEK293 cells. Point mutations and specific antibodies against phosphorylated S481 or S488 demonstrated the importance of these residues for the PKC-dependent modulation of Kv2.2. In layer II pyramidal neurons in cortical slices, activation of PKC similarly regulated native Kv2.2 channels and simultaneously reduced the frequency of action potentials. In conclusion, this study provides the first evidence to our knowledge that PKC-induced phosphorylation of the Kv2.2 channel controls the excitability of cortical pyramidal neurons.
Action Potentials ; HEK293 Cells ; Humans ; Protein Kinase C/metabolism* ; Pyramidal Cells/enzymology* ; Shab Potassium Channels/genetics*

Cerebellar Purkinje cells (PCs) exhibit two types of discharge activities: simple spike (SS) and complex spike (CS). Previous studies found that noradrenaline (NA) can inhibit CS and bidirectionally regulate SS, but the enhancement of NA on SS is overwhelmed by the strong inhibition of excitatory molecular layer interneurons. However, the mechanism underlying the effect of NA on SS discharge frequency is not clear. Therefore, in the present study, we examined the mechanism underlying the increasing effect of NA on SS firing of PC in mouse cerebellar cortex in vivo and in cerebellar slice by cell-attached and whole-cell recording technique and pharmacological methods. GABA_A receptor was blocked by 100 µmol/L picrotoxin in the whole process. In vivo results showed that NA significantly reduced the number of spikelets of spontaneous CS and enhanced the discharge frequency of SS, but did not affect the discharge frequency of CS. In vitro experiments showed that NA reduced the number of CS spikelets and after hyperpolarization potential (AHP) induced by electrical stimulation, and increased the discharge frequency of SS. NA also reduced the amplitude of excitatory postsynaptic current (EPSC) of parallel fiber (PF)-PC and significantly increased the paired-pulse ratio (PPR). Application of yohimbine, an antagonist of α2-adrenergic receptor (AR), completely eliminated the enhancing effect of NA on SS. The α2-AR agonist, UK14304, also increased the frequency of SS. The β-AR blocker, propranolol, did not affect the effects of NA on PC. These results suggest that in the absence of GABA_A receptors, NA could attenuate the synaptic transmission of climbing fiber (CF)-PC via activating α2-AR, inhibit CS activity and reduce AHP, thus enhancing the SS discharge frequency of PC. This result suggests that NA neurons of locus coeruleus can finely regulate PC signal output by regulating CF-PC synaptic transmission.
Action Potentials/physiology* ; Animals ; Cerebellar Cortex/metabolism* ; Cerebellum/metabolism* ; Mice ; Norepinephrine/pharmacology* ; Purkinje Cells/metabolism* ; Receptors, Adrenergic, alpha-2/metabolism* ; Receptors, GABA-A/metabolism*

Diverse types of GABAergic interneurons tend to specialize in their inhibitory control of various aspects of cortical circuit operations. Among the most distinctive interneuron types, chandelier cells (i.e., axo-axonic cells) are a bona fide cell type that specifically innervates pyramidal cells at the axon initial segment, the site of action potential initiation. Chandelier cells have been speculated to exert ultimate inhibitory control over pyramidal cell spiking. Thus, chandelier cells appear to share multiple similarities with basket cells, not only in firing pattern (fast spiking) and molecular components, but also in potentially perisomatic inhibitory control. Unlike basket cells, however, synaptic recruitment of chandelier cells is little known yet. Here, we examined the mediodorsal thalamocortical input to both chandelier cells and basket cells in medial prefrontal cortex, through combining mouse genetic, optogenetic and electrophysiological approaches. We demonstrated that this thalamocortical input produced initially weak, but facilitated synaptic responses at chandelier cells, which enabled chandelier cells to spike persistently. In contrast, this thalamocortical input evoked initially strong, but rapidly depressed synaptic responses at basket cells, and basket cells only fired at the initiation of input. Overall, the distinct synaptic recruitment dynamics further underscores the differences between chandelier cells and basket cells, suggesting that these two types of fast spiking interneurons play different roles in cortical circuit processing and physiological operation.
Mice ; Animals ; Neurons/physiology* ; Pyramidal Cells/physiology* ; Interneurons ; Action Potentials/physiology* ; Synaptic Transmission

The back-propagating action potential (bpAP) is crucial for neuronal signal integration and synaptic plasticity in dendritic trees. Its properties (velocity and amplitude) can be affected by dendritic morphology. Due to limited spatial resolution, it has been difficult to explore the specific propagation process of bpAPs along dendrites and examine the influence of dendritic morphology, such as the dendrite diameter and branching pattern, using patch-clamp recording. By taking advantage of Optopatch, an all-optical electrophysiological method, we made detailed recordings of the real-time propagation of bpAPs in dendritic trees. We found that the velocity of bpAPs was not uniform in a single dendrite, and the bpAP velocity differed among distinct dendrites of the same neuron. The velocity of a bpAP was positively correlated with the diameter of the dendrite on which it propagated. In addition, when bpAPs passed through a dendritic branch point, their velocity decreased significantly. Similar to velocity, the amplitude of bpAPs was also positively correlated with dendritic diameter, and the attenuation patterns of bpAPs differed among different dendrites. Simulation results from neuron models with different dendritic morphology corresponded well with the experimental results. These findings indicate that the dendritic diameter and branching pattern significantly influence the properties of bpAPs. The diversity among the bpAPs recorded in different neurons was mainly due to differences in dendritic morphology. These results may inspire the construction of neuronal models to predict the propagation of bpAPs in dendrites with enormous variation in morphology, to further illuminate the role of bpAPs in neuronal communication.
Action Potentials/physiology* ; Dendrites/physiology* ; Neurons/physiology* ; Neuronal Plasticity ; Pyramidal Cells/physiology*

Objective: To compare the difference between the built-in and external reference electrode of microwire electrode array in the process of recording rat brain neuron firings, optimizing the production and embedding of the microwire electrode array, and providing a more affordable and excellent media tool for multi-channel electrophysiological real-time recording system. Methods: A 16 channel microwire electrode array was made by using nickel chromium alloy wires, circuit board, electrode pin and ground wires (silver wires). The reference electrode of the microwire electrode array was built-in (the reference electrode and electrode array were arranged in parallel) or external (the reference electrode and ground wire were welded at both ends of one side of the electrode), and the difference between the two electrodes was observed and compared in recording neuronal discharges in ACC brain area of rats. Experimental rats were divided into built-in group and external group, n=8-9. The test indicators included signal-to-noise ratio (n=8), discharge amplitude (n=380) and discharge frequency (n=54). Results: The microwire electrode array with both built-in and external reference electrodes successfully recorded the electrical signals of neurons in the ACC brain region of rats. Compared with the external group, the electrical signals of neurons in built-in group had the advantages of a higher signal-to-noise ratio (P＜0.05), a smaller amplitude of background signals and less noise interference, and a larger discharge amplitude(P＜0.05); there was no significant difference in spike discharge frequency recorded by these two types of electrodes (P＞0.05). Conclusion: When recording the electrical activity of neurons in the ACC brain region of rats, the microwire electrode array with built-in reference electrode recorded electrical signals with higher signal-to-noise ratio and larger discharge amplitude, providing a more reliable tool for multi-channel electrophysiology technology.
Action Potentials/physiology* ; Animals ; Brain ; Electrophysiological Phenomena ; Microelectrodes ; Neurons ; Rats