The Effects of NMDA Subunit Composition on Calcium Influx and Spike Timing-Dependent Plasticity in Striatal Medium Spiny Neurons

Calcium through NMDA receptors (NMDARs) is necessary for the long-term potentiation (LTP) of synaptic strength; however, NMDARs differ in several properties that can influence the amount of calcium influx into the spine. These properties, such as sensitivity to magnesium block and conductance decay kinetics, change the receptor's response to spike timing dependent plasticity (STDP) protocols, and thereby shape synaptic integration and information processing. This study investigates the role of GluN2 subunit differences on spine calcium concentration during several STDP protocols in a model of a striatal medium spiny projection neuron (MSPN). The multi-compartment, multi-channel model exhibits firing frequency, spike width, and latency to first spike similar to current clamp data from mouse dorsal striatum MSPN. We find that NMDAR-mediated calcium is dependent on GluN2 subunit type, action potential timing, duration of somatic depolarization, and number of action potentials. Furthermore, the model demonstrates that in MSPNs, GluN2A and GluN2B control which STDP intervals allow for substantial calcium elevation in spines. The model predicts that blocking GluN2B subunits would modulate the range of intervals that cause long term potentiation. We confirmed this prediction experimentally, demonstrating that blocking GluN2B in the striatum, narrows the range of STDP intervals that cause long term potentiation. This ability of the GluN2 subunit to modulate the shape of the STDP curve could underlie the role that GluN2 subunits play in learning and development

Computational, Investigational Explorations on Structural, Electro-Optic Behavior of Pelargonidin Organic Colorant for TiO₂ Based DSSCs

In an expedition for green-energy generation and to lower the cost per watt of solar energy, environmentally friendly biotic colorants were separated from Tectona grandis seeds. The prime colorant in the extract is pelargonidin which sensitizes titanium dioxide (TiO2)-based photo anodes. The pelargonidin-sensitized TiO2 nanomaterials endured structural, photosensitive, spectral and current-voltage interpretations. Frontier molecular orbital analysis, physicochemical and electronic parameter computation, UV–visible and DOS spectral analysis, van der Waals prediction and molecular electrostatic potential map were performed theoretically with Gaussian tools, and IR symmetry response was computed using the crystal maker software package. The pelargonidin-sensitized TiO2-created dye-sensitized solar cells which exhibited capable solar light energy to photon conversion proficiency. For comparative purposes, the commercial P25 Degussa TiO2-based DSSC was also fabricated and its proficiency was analyzed. The commercial TiO2 exhibited 57 % higher proficiency in comparison to the sol-gel-derived TiO2-based DSSC