Paraventricular Thalamus Dynamically Modulates Aversive Memory via Tuning Prefrontal Inhibitory Circuitry.

The impact of stress on the formation and expression of memory is well studied, especially on the contributions of stress hormones. But how stress affects brain circuitry dynamically to modulate memory is far less understood. Here, we used male C57BL6/J mice in an auditory fear conditioning as a model system to examine this question and focused on the impact of stress on dorsomedial prefrontal cortex (dmPFC) neurons which play an important role in probabilistic fear memory. We found that paraventricular thalamus (PVT) neurons are robustly activated by acute restraining stress. Elevated PVT activity during probabilistic fear memory expression increases spiking in the dmPFC somatostatin neurons which in turn suppresses spiking of dmPFC parvalbumin (PV) neurons, and reverts the usual low fear responses associated with probabilistic fear memory to high fear. This dynamic and reversible modulation allows the original memory to be preserved and modulated during memory expression. In contrast, elevated PVT activity during fear conditioning impairs synaptic modifications in the dmPFC PV-neurons and abolishes the formation of probabilistic fear memory. Thus, PVT functions as a stress sensor to modulate the formation and expression of aversive memory by tuning inhibitory functions in the prefrontal circuitry.SIGNIFICANCE STATEMENT The impact of stress on cognitive functions, such as memory and executive functions, are well documented especially on the impact by stress hormone. However, the contributions of brain circuitry are far less understood. Here, we show that a circuitry-based mechanism can dynamically modulate memory formation and expression, namely, higher stress-induced activity in paraventricular thalamus (PVT) impairs the formation and expression of probabilistic fear memory by elevating the activity of somatostatin-neurons to suppress spiking in dorsomedial prefrontal parvalbumin (PV) neurons. This stress impact on memory via dynamic tuning of prefrontal inhibition preserves the formed memory but enables a dynamic expression of memory. These findings have implications for better stress coping strategies as well as treatment options including better drug targets/mechanisms.

Preparation of a novel non-burning polyaluminum chloride residue(PACR) compound filler and its phosphate removal mechanisms.

As an inevitable industrial by-product, polyaluminum chloride residue (PACR) will cause serious harm to the environment if directly buried and dumped. The aim of this paper was searched a new economical, environmental, and practical way of utilization for PACR. In this paper, a novel non-burning PACR compound filler was made from mainly PACR. The prepared compound filler has excellent physical properties and phosphate adsorption efficiency of up to 99.9%. Static adsorption experiments showed that the adsorption process of phosphorus by the compound filler conformed to the pseudo-second-order kinetic model and intra-particle diffusion model. Langmuir and Freundlich isotherm models described the phosphorus adsorption process well, and the maximum phosphate adsorption capacity arrived at 42.55 mg/g. The phosphate adsorption by the compound filler is a spontaneous endothermic process. The main mechanisms are ligand exchange and Lewis acid-base interactions; calcium and aluminum play important roles in the adsorption of phosphorus by the compound filler. Dynamic column experiments showed that as much as 90% of the phosphorus removal by compound filler, and the phosphorus concentration decreased from 1 to ~0.1mg/L. The results provide a new waste resource utilization method for PACR and show the good application potential of prepared compound filler in constructed wetlands.