Studying the Integration of Adult-born Neurons

Neurogenesis occurs in adult mammalian brains in the sub-ventricular zone (SVZ) of the lateral ventricle and in the sub-granular zone (SGZ) of the hippocampal dentate gyrus throughout life. Previous reports have shown that adult hippocampal neurogenesis is associated with diverse brain disorders, including epilepsy, schizophrenia, depression and anxiety (1). Deciphering the process of normal and aberrant adult-born neuron integration may shed light on the etiology of these diseases and inform the development of new therapies

Inside-Out Radial Migration Facilitates Lineage-Dependent Neocortical Microcircuit Assembly

SummaryNeocortical excitatory neurons migrate radially along the glial fibers of mother radial glial progenitors (RGPs) in a birth-date-dependent inside-out manner. However, the precise functional significance of this well-established orderly neuronal migration remains largely unclear. Here, we show that strong electrical synapses selectively form between RGPs and their newborn progeny and between sister excitatory neurons in ontogenetic radial clones at the embryonic stage. Interestingly, the preferential electrical coupling between sister excitatory neurons, but not that between RGP and newborn progeny, is eliminated in mice lacking REELIN or upon clonal depletion of DISABLED-1, which compromises the inside-out radial neuronal migration pattern in the developing neocortex. Moreover, increased levels of Ephrin-A ligand or receptor that laterally disperse sister excitatory neurons also disrupt preferential electrical coupling between radially aligned sister excitatory neurons. These results suggest that RGP-guided inside-out radial neuronal migration facilitates the initial assembly of lineage-dependent precise columnar microcircuits in the neocortex

Observation of fast sound in two-dimensional dusty plasma liquids

Equilibrium molecular dynamics simulations are performed to study two-dimensional (2D) dusty plasma liquids. Based on the stochastic thermal motion of simulated particles, the longitudinal and transverse phonon spectra are calculated, and used to determine the corresponding dispersion relations. From there, the longitudinal and transverse sound speeds of 2D dusty plasma liquids are obtained. It is discovered that, for wavenumbers beyond the hydrodynamic regime, the longitudinal sound speed of a 2D dusty plasma liquid exceeds its adiabatic value, i.e., the so-called fast sound. This phenomenon appears at roughly the same length scale of the cutoff wavenumber for transverse waves, confirming its relation to the emergent solidity of liquids in the non-hydrodynamic regime. Using the thermodynamic and transport coefficients extracted from the previous studies, and relying on the Frenkel theory, the ratio of the longitudinal to the adiabatic sound speeds is derived analytically, providing the optimal conditions for fast sound, which are in quantitative agreement with the current simulation results.Comment: v1: 7 pages, 6 figure

Interplay between a Mental Disorder Risk Gene and Developmental Polarity Switch of GABA Action Leads to Excitation-Inhibition Imbalance

Acknowledgments: We thank members of the Ming and Song laboratories for comments and suggestions, D. Johnson for technical support, and J. Schnoll for lab coordination. This work was supported by grants from the National Institutes of Health (NIH) (R01MH105128 and R35NS097370 to G.-L.M. and R37NS047344 to H.S.) and from the National Alliance for Research on Schizophrenia and Depression (NARSAD) to G.-L.M., H.S., and E.K. Author Contributions: E.K. and J.S contributed equally to this work. J.S. performed electrophysiological analysis and E.K. performed morphological analysis. Y.L. and K.-S.H. contributed to electrophysiology data collection, Y.G. and S.G. helped with some of the retrovirus production, and B.B. helped with rabies synaptic tracing. J.P., J.H.L., Q.H., W.L., and K.M.C. contributed to additional data collection. E.K., J.S., H.S., and G-L.M. designed the project and wrote the manuscript.Peer reviewedPublisher PD

Lateral dispersion is required for circuit integration of newly generated dentate granule cells

The process of circuit integration of newly-generated dentate granule cells of the hippocampus has been presumed to be a dynamic process. In fact, little is known regarding the initial development of newly generated neurons prior to circuit integration and the significance of this stage for circuit integration. Here, using advanced live imaging methods, we systematically analyze the dynamic dispersion of newly generated neurons in the neurogenic zone and observe that cells that are physically adjacent coordinate their lateral dispersion. Whole-cell recordings of adjacent newly generated neurons reveal that they are coupled via gap junctions. The dispersion of newly generated cells in the neurogenic zone is restricted when this coupling is disrupted, which severely impairs their subsequent integration into the hippocampal circuit. The results of this study reveal that the dynamic dispersion of newly generated dentate granule cells in the neurogenic zone is a required developmental stage for circuit integration