Sequential processing facilitates Hebb repetition learning in visuospatial domains.

Exposure to the same information improves auditory/verbal short-term memory performance, but such improvement is not always observed in visual short-term memory. In this study, we demonstrate that sequential processing makes visuospatial repetition learning efficient in a paradigm that employs a similar design previously used for an auditory/verbal domain. When we presented sets of color patches simultaneously in Experiments 1-4, recall accuracy did not increase with repetition; however, once color patches were presented sequentially in Experiment 5, accuracy did increase rapidly with repetition, even when participants engaged in articulatory suppression. Moreover, these learning dynamics matched those in Experiment 6, which used verbal materials. These findings suggest that (a) sequential focus on each item facilitates a repetition learning effect, indicating a temporal bottleneck is involved early in this process and (b) repetition learning is mechanistically similar across sensory modalities even though these modalities differently specialize in processing spatial or temporal information. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Improving Brightness and Stability of Si-Rhodamine for Super-Resolution Imaging of Mitochondria in Living Cells.

Photostable and bright organic dyes emitting in the near-infrared region are highly desirable for long-term dynamic bioimaging. Herein, we report a synthetic approach to build novel methoxy modified Si-rhodamine (SiRMO) dyes by introducing the methoxybenzene on the xanthene moiety. The brightness of SiRMO increased from 2300 M-1 cm-1 (SiRMO-0) to 49000 M-1 cm-1 (SiRMO-2) when the substituent 2,5-dimethoxybenzene was replaced with 2,6-dimethoxybenzene. Moreover, the stability of SiRMO-2 was significantly improved due to the steric hindrance protection of the two methoxy groups on the ninth carbon atom of the xanthene. After fast cellular uptake, the SiRMO dyes selectively stained the mitochondria with a low background in live cultured cells and primary neurons. The high brightness and stability of SiRMO-2 significantly improved the capability of monitoring mitochondria dynamic processes in living cells under super-resolution conditions. Moreover, with the fluorescence nanoscopy techniques, we observed the structure of mitochondrial cristae and mitochondria fission, fusion, and apoptosis with a high temporal resolution. Under two-photon illumination, SiRMO-2 showed also enhanced two-photon brightness and stability, which are important for imaging in thick tissue.