Yi Jiang

Size perception of visual objects is highly context dependent. Here we report a novel perceptual size illusion that the self-face, being a unique and distinctive self-referential stimulus, can enlarge its perceived size. By using a size discrimination paradigm, we found that the self-face was perceived as significantly larger than the other-face of the same size. This size overestimation effect was not due to the familiarity of the self-face, since it could be still observed when the self-face was directly compared with a famous face. More crucially, such illusion effect could be extended to a new cartoon face that was transiently associated with one's own face and could also exert further contextual influences on visual size perception of other objects. These findings together highlight the role of self-awareness in visual size perception and point to a special mechanism of size perception tuned to self-referential information.

The human brain optimises cognitive resource allocation to enhance the processing speed and efficiency of vital information for better survival and adaptation in response to threat signals. Previous studies found that fearful expressions, as visual cues signalling threats, can not only have advantages in entering and remaining in awareness, but also enhance subsequent perceptual processing of low-spatial-frequency (LSF) information. However, it remains unknown whether the enhanced perceptual processing of LSF induced by fearful expressions also grants LSF information a competitive advantage in awareness. To this end, we employed a binocular rivalry paradigm to measure awareness of Gabor patches with low or high spatial frequencies following the rapid priming of fearful versus neutral expressions. The results revealed that the relative dominance of LSF over high-spatial-frequency (HSF) Gabor patches was markedly heightened following brief exposure to fearful compared with neutral expressions. This effect was found for both upright and inverted expressions, indicating it is independent of face configuration. Our study thus suggests a feature-based perceptual optimisation mechanism with evolutionary significance, potentially optimising cognitive resource allocation in threatening situations.

Background: The p53 tumor suppressor and its related protein, p73, share a homologous DNA binding domain, and mouse genetics studies have suggested that they have overlapping as well as distinct biological functions. Both p53 and p73 are activated by genotoxic stress to regulate an array of cellular responses. Previous studies have suggested that p53 and p73 independently activate the cellular apoptotic program in response to cytotoxic drugs. The goal of this study was to compare the promoter-binding activity of p53 and p73 at steady state and after genotoxic stress induced by hydroxyurea. Results: We employed chromatin immunoprecipitation, the NimbleGen promoter arrays and a model-based algorithm for promoter arrays to identify promoter sequences enriched in anti-p53 or anti-p73 immunoprecipitates, either before or after treatment with hydroxyurea, which increased the expression of both p53 and p73 in the human colon cancer cell line HCT116-3. We calculated a model-based algorithm for promoter array score for each promoter and found a significant correlation between the promoter occupancy profiles of p53 and p73. We also found that after hydroxyurea treatment, the p53-bound promoters were still bound by p73, but p73 became associated with additional promoters that that did not bind p53. In particular, we showed that hydroxyurea induces the binding of p73 but not p53 to the promoter of MLH3, which encodes a mismatch repair protein, and causes an up-regulation of the MLH3 mRNA. Conclusion: These results suggest that hydroxyurea exerts differential effects on the promoter-binding functions of p53 and p73 and illustrate the power of model-based algorithm for promoter array in the analyses of promoter occupancy profiles of highly homologous transcription factors. © 2009 Huang et al; licensee BioMed Central Ltd.

We used functional magnetic resonance imaging to examine the interactive effects of perceived competence and task interest on the cognitive and affective responses to negative feedback. Twenty-four undergraduates performed both interesting and uninteresting tasks and received failure feedback. The participants’ perceived competence in the task was manipulated between subjects prior to scanning with bogus feedback. The results showed that negative feedback processing was contingent upon both perceived competence and task interest. The most adaptive coping mechanism, indicated by activation in the cognitive control network and attenuation in the negative affect region, was identified for the high-competence and high-interest combination. When either competence or interest was low, signals in the cognitive control network were weaker. The most detrimental activation patterns were observed for the combination of low-competence and high interest. Our results reveal the combination of task and learner characteristics that best harnesses the potential benefits of negative feedback and illustrate the neuroscientific mechanisms underlying this observation.