T-type Ca2+ and persistent Na+ currents synergistically elevate ventral, not dorsal, entorhinal cortical stellate cell excitability

The medial entorhinal cortex (mEC) plays a salient role in physiological processes such as spatial cognition and spatial coding. mEC layer II stellate neurons, in particular, influence these processes. Interestingly, ventral and dorsal stellate neurons diversely affect these processes and have distinct intrinsic membrane properties and action potential firing patterns. Little, though, is known about how ventral stellate neuron intrinsic excitability is regulated. We show that ventral stellate neurons predominantly possess T-type Ca2+ currents encoded by CaV3.2 subunits, with dorsal stellate neurons having small or no currents. Further, twice as much CaV3.2 mRNA was present in ventral than dorsal mEC. In line with T-type, CaV3.2 Ca2+ current biophysical properties, depolarising stimuli activated these currents in ventral, but not dorsal, neurons. Here, these currents acted in concert with persistent Na+ currents to elevate input resistance and tonic action potential firing. CaV3.2 currents also enhanced excitatory post-synaptic potential decay and integration solely in ventral neurons. These results reveal that CaV3.2 currents, together with persistent Na+ currents, impart the characteristic intrinsic membrane and firing properties of ventral stellate neurons. This signifies that specific voltage-gated conductances distinctly affect ventral and dorsal mEC stellate neuron activity and functions such as spatial memory and spatial navigation.

Effects of doping high-valence transition metal (V, Nb and Zr) ions on the structure and electrochemical performance of LIB cathode material LiNi0.8Co0.1Mn0.1O2

Ni-rich layered oxides, like LiNi0.8Co0.1Mn0.1O2 (NCM811), have been widely investigated as cathodes for high energy density. However, gradual structural transformation during cycling can lead to capacity degradation and potential decay...

Effect of Aging under AC Superimposed Harmonic Voltage on Trap and Carrier Transport Properties of Silicone Rubber

The rapid growth of power grid capacity and the widespread use of a large number of power electronics and non-linear loads have led to harmonics in the power system. Harmonics in the power system will cause safety hazards to the normal operation of power equipment, exacerbate the aging of insulation materials, and reducing the overall operation reliability of the system. In the present work, we used power frequency ac voltage superimposed harmonics to carry out ageing experiments on power cable terminals. Then, we tested the infrared spectra, dielectric spectra, electrical conductivity, and surface potential decay characteristics of silicone rubber insulation materials on the cable terminals aged for different times. The experimental results show that the dielectric constant and dielectric loss of silicone rubber gradually increase with the aging time. In particular, the dielectric loss of silicone rubber changed greatly at low frequencies. The effect of dc conductance of aged silicone rubber on dielectric loss is significantly enhanced at low frequencies, which causes the dielectric loss to increase as the frequency decreases following an inverse power law. The surface potential decay rates of silicone rubber insulation after positive and negative corona charging accelerate with increasing the aging time, which is consistent with the experimental results of electrical conductivity. By analyzing the distribution characteristics of electron and hole traps in silicone rubbers, it is found that the trap energy levels of electron and hole traps become shallower as the operating time increases. The calculation of the carrier hopping conduction model shows that the shallow trap formed with increasing the aging time will lead to increases in both carrier mobility and conductivity. When the conductivity rises to a certain value, the silicone rubber will lose its insulation performance, resulting in insulation failure.