The optical properties of amorphous and polycrystalline Ba x Sr 1−x TiO 3 (BST) thin films fabricated on Si(100) substrates by a sol-gel spin-coating technique were investigated by spectroscopic ellipsometry (SE). The spectrum of the extinction coefficient k was obtained by using the refractive index and structure parameters determined by SE in the photon energy range of 2.1-5.2 eV. A fourphase fitting model was employed to describe the optical properties of the BST thin films; the spectra of their optical constants and the band gap energy E g were determined by means of optimization. In addition, the refractive index dispersion data related to the short-range-order structure of the films agreed well with the single-oscillation energy model. The dependence of the refractive index, k and E g on annealing temperature were analysed. The variation of optical band gap energy with composition was investigated by changing the content of barium in the films.
The secondary motor cortex (M2) encodes choice-related information and plays an important role in cue-guided actions. M2 neurons innervate the dorsal striatum (DS), which also contributes to decision-making behavior, yet how M2 modulates signals in the DS to influence perceptual decision-making is unclear. Using mice performing a visual Go/No-Go task, we showed that inactivating M2 projections to the DS impaired performance by increasing the false alarm (FA) rate to the reward-irrelevant No-Go stimulus. The choice signal of M2 neurons correlated with behavioral performance, and the inactivation of M2 neurons projecting to the DS reduced the choice signal in the DS. By measuring and manipulating the responses of direct or indirect pathway striatal neurons defined by M2 inputs, we found that the indirect pathway neurons exhibited a shorter response latency to the No-Go stimulus, and inactivating their early responses increased the FA rate. These results demonstrate that the M2-to-DS pathway is crucial for suppressing inappropriate responses in perceptual decision behavior.
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