Ion-specific channels in artificial membranes have been formed by the addition of gramicidin A, alamethicin, polyene antibiotics and some proteins to the solution surrounding the bilayer lipid membrane. Until now there have been no reports of single-ion channels in unmodified lipid membranes. We have now studied the electrical conductance of planar lipid bilayers membranes made of synthetic distearoylphosphorylcholine (DSPC). Current fluctuations of amplitude approximately 1pA and duration approximately 1 s have been discovered at phase transition temperature, which shows that the appearance of ionic channels may be the result of lipid domain interactions. This would explain the dramatic increase in ion permeability observed in liposomes during phase transition. We suggest that these channels could conduct the transmembrane ionic current in biological membranes without the involvement of peptides and proteins.

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Approaches to predictably control neural oscillations are needed to understand their causal role in brain function in healthy and diseased states and to advance the development of neuromodulation therapies. In this article, we present a neural control and optimization framework to actively suppress or amplify neural oscillations observed in local field potentials in real-time by using electrical stimulation. The rationale behind this control approach is that neural oscillatory activity evoked by electrical pulses can suppress or amplify spontaneous oscillations via destructive or constructive interference when stimulation pulses are continuously delivered at precise phases of these oscillations in a closed-loop scheme. We tested this technique in two nonhuman primates that exhibited a robust increase in low-frequency (8-30 Hz) oscillatory power in the subthalamic nucleus following administration of the neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). The control approach was capable of actively and robustly suppressing or amplifying low-frequency oscillations in real-time in the studied subjects. Significance StatementWe developed and tested an approach to systematically and predictably control neural oscillations recorded from local field potentials in-vivo by using electrical stimulation. This neural modulation technique is capable of actively suppressing or amplifying neural oscillations with the resolution and time specificity needed to characterize the functional role of oscillatory dynamics in brain circuits. We resolve the experimentally-intractable problem of finding optimal stimulation parameters to suppress or amplify neural oscillations by using subject-specific neurophysiological data and data-driven computer simulations. Together these neural control and optimization approaches allow one to characterize in controlled experiments the role of circuit-level neural oscillations in brain function and study electrical stimulation therapies that predictably modulate brain oscillations.

The valence fluctuations which are related to the charge disproportionation of phosphorous ions P 4+ + P 4+ → P 3+ + P 5+ are the origin of ferroelectric and quantum paraelectric states in Sn(Pb)2P2S6 semiconductors. They involve recharging of SnPS3 or PbPS3 structural groups which could be represented as half-filled sites in the crystal lattice. Temperature-pressure phase diagram for Sn2P2S6 compound and temperature-composition phase diagram for (PbySn1−y)2P2S6 mixed crystals, which include tricritical points and where a temperature of phase transitions decrease to 0 K, together with the data about some softening of low energy optic phonons and rise of dielectric susceptibility at cooling in quantum paraelectric state of Pb2P2S6 are analyzed by GGA electron and phonon calculations and compared with electronic correlations models. The anharmonic quantum oscillators model is developed for description of phase diagrams and temperature dependence of dielectric susceptibility.

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