We review a statistical physics approach for reduced descriptions of neuronal network dynamics. From a network of all-to-all coupled, excitatory integrate-and-fire neurons, we derive a (2+1)-D advection-diffusion equation for a probability distribution function, which describes neuronal population dynamics. We further show how to derive a (1+1)-D kinetic equation, using a moment closure scheme, without introducing any new parameters to the system. We demonstrate the numerical accuracy of our kinetic theory by comparing its results to Monte Carlo simulations of the full integrate-and-fire neuronal network.
Animals ; Computer Simulation ; Humans ; Models, Neurological ; Monte Carlo Method ; Nerve Net ; physiology ; Neural Networks (Computer) ; Neurons ; physiology

We review our work on computational modeling of the mammalian visual cortex. In particular, we explain the network mechanism of how simple and complex cells arise in a large scale neuronal network model of primary visual cortex. The simple cells are so-called because they respond approximately linearly to visual stimulus, whereas the complex cells exhibit nonlinear response to visual stimulation. Our model reproduces qualitatively the experimentally observed distributions of simple and complex cells.
Animals ; Computer Simulation ; Humans ; Models, Neurological ; Nerve Net ; physiology ; Neurons ; physiology ; Photic Stimulation ; Visual Cortex ; cytology ; physiology

OBJECTIVE: To investigate whether CKLF-like MARVEL transmembrane domain-containing protein 2 (CMTM2) is involved in spermatogenesis in mice. CMTM2 is highly expressed in testis, and could possibly be a potential spermagogenesis specific gene. METHODS: CMTM2-deficient mouse model was generated. Northern, RT-PCR and Western blotting analysis were performed on total RNA derived from wild-type (WT, CMTM2+/+) and CMTM2+/- (heterozygote) and CMTM2-/-(homozygote) mice to examine the CMTM2 level. The number of litters and the number of pups were counted and pregnancy rates calculated. The motility and morphology of the sperm and the histology of testes were analyzed. Serum testosterone and FSH concentrations were also measured. Standard t-tests were used and standard error of means were calculated. RESULTS: CMTM2 was highly expressed in a finely regulated pattern in the mouse testis during spermatogenesis. The body weight of adult mice with CMTM2 deficiency was not significantly different from that of wild type mice. No obvious anatomical or behavioral abnormalities were observed. The testis of CMTM2-/- was smaller than that of CMTM2+/+ mice. The testis diameter in wild mice and CMTM2 null mice were (11.32±1.21) mm vs. (8.29±1.92) mm (P<0.05), and the weights were (101.63±2.33) mg vs. (85.22±2.84) mg (P<0.05), respectively. Female CMTM2 null mice were fertile, indicating that CMTM2 was not required for female gametogenesis. The CMTM2-/- mice produced virtually no sperm, and CMTM2+/- mice sperm count showed a significant decline. In terms of sperm morphorlogy study, more round spermatids could be observed in the heterozygote group, compared with the wild type group; while in the homozygote group, a large amount of round spermatids could be observed because of complete arrest of spermiogenesis. The hormone levels were not significantly different. The CMTM2-/- male mice were sterile due to a late, complete arrest of spermiogenesis. The organized architecture of the seminiferous epithelium of the seminiferous tubules seen in CMTM2+/+ mice was lost in CMTM2-/- mice. CONCLUSION This study suggests CMTM2 is not required for embryonic development in the mouse but is essential for spermiogenesis, however, further studies are required for more detailed mechanism study.
Animals ; Chemokines/metabolism* ; Female ; Heterozygote ; MARVEL Domain-Containing Proteins/metabolism* ; Male ; Mice ; Mice, Knockout ; Pregnancy ; Spermatogenesis ; Spermatozoa ; Testis

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*