Biasing visual selection: functional neuroimaging of the interplay between spatial cueing and feature memory guidance

The authors investigate the interplay between spatial attention and memory-based feature guidance of visual selection. Three types of guidance were tested: working memory, spatial cueing and passive memory. In all cases the memory-cue was not relevant to a subsequent search task, whilst the spatial cue always provided valid information. Behaviourally, search performance was influenced by spatial cueing and by feature-based cueing from the contents of working memory; both forms of guidance interacted, with feature guidance being more effective when the target's location was not pre-cued. Spatial cueing recruited the dorsal fronto-parietal network which was silent during the WM-only condition. Memory guidance of selection was reflected in activity in a frontal-temporal-occipital network. Interestingly, when spatial and memory guidance were pitted against each other, neural activity in this latter network was greatly attenuated. Connectivity analysis showed that the posterior parietal cortices inhibit the responses of occipital and temporal regions to the onset of memory-items in the search display. In the presence of a reliable spatial cue the posterior parietal cortex resumes control of attentional deployment. These results illustrate how different forms of attention guidance interact to optimise visual selection.

Alisol B, a novel inhibitor of the sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase pump, induces autophagy, endoplasmic reticulum stress, and apoptosis

Emerging evidence suggests that autophagic modulators have therapeutic potential. This study aims to identify novel autophagic inducers from traditional Chinese medicinal herbs as potential antitumor agents. Using an image-based screen and bioactivity-guided purification, we identified alisol B 23-acetate, alisol A 24-acetate, and alisol B from the rhizome of Alisma orientale as novel inducers of autophagy, with alisol B being the most potent natural product. Across several cancer cell lines, we showed that alisol B-treated cells displayed an increase of autophagic flux and formation of autophagosomes, leading to cell cycle arrest at the G(1) phase and cell death. Alisol B induced calcium mobilization from internal stores, leading to autophagy through the activation of the CaMKK-AMPK-mammalian target of rapamycin pathway. Moreover, the disruption of calcium homeostasis induces endoplasmic reticulum stress and unfolded protein responses in alisol B-treated cells, leading to apoptotic cell death. Finally, by computational virtual docking analysis and biochemical assays, we showed that the molecular target of alisol B is the sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase. This study provides detailed insights into the cytotoxic mechanism of a novel antitumor compound.