Immune privilege for stem cells: not as simple as it looked

A recent paper in PNAS (Swijnenburg et al., 2008) reveals that human embryonic stem cells are not immune privileged. Potential therapeutic use of these cells will thus depend on the development of new strategies to counter foreign graft rejection by patient immune systems.     

Replication licensing: oops! ... I did it again

All eukaryotes use multiple controls to restrict DNA replication to once per cell cycle. Nevertheless, inactivation of a single gene, cul-4, causes massive re-replication in Caenorhabditis elegans. A novel study explains this dramatic phenotype by demonstrating that the CUL-4 E3 ligase simultaneously controls two critical licensing factors: CDT-1 and CDC-6.     

On again, off again: the SRC-3 transcriptional coactivator moonlights as a translational corepressor

In a recent issue of Molecular Cell, Yu et al. (2007) reported that the steroid receptor coactivator-3 (SRC-3) has a novel cytoplasmic function: it activates the translational silencers TIA-1 and TIAR and thus inhibits the translation of proinflammatory cytokines.     

Calcium signalling: IP3 rises again...and again

Recent results indicate that 'regulators of G-protein signalling' may contribute to the generation of receptor-specific patterns of cytosolic Ca2+ oscillations by associating with specific receptors, accelerating G-protein inactivation and responding to changes in cytosolic Ca2+.     

Dream Poetry as Dream Work

This paper explores the relationship between dream poetry and dream work by presenting a representative dream poem, along with the text of the dream that inspired it; examining some of its poetic qualities and showing how these figured in the writing of the poem; and comparing the dream writing process to dream interpretation and to Jungian active imagination work. The formal demands of poetry introduce a unique type of critical thought into the creative process that develops the dream material in ways different from other forms of dream work. Writing dream poetry differs from both dream interpretation and active imagination in important ways, but can be viewed as a form of non-interpretative dream work. These observations are probably generalizable to all forms of dream writing and dream art.     

Hearing it again and again: on-line subcortical plasticity in humans

Background

Human brainstem activity is sensitive to local sound statistics, as reflected in an enhanced response in repetitive compared to pseudo-random stimulus conditions [1]. Here we probed the short-term time course of this enhancement using a paradigm that assessed how the local sound statistics (i.e., repetition within a five-note melody) interact with more global statistics (i.e., repetition of the melody).

Methodology/Principal Findings

To test the hypothesis that subcortical repetition enhancement builds over time, we recorded auditory brainstem responses in young adults to a five-note melody containing a repeated note, and monitored how the response changed over the course of 1.5 hrs. By comparing response amplitudes over time, we found a robust time-dependent enhancement to the locally repeating note that was superimposed on a weaker enhancement of the globally repeating pattern.

Conclusions/Significance

We provide the first demonstration of on-line subcortical plasticity in humans. This complements previous findings that experience-dependent subcortical plasticity can occur on a number of time scales, including life-long experiences with music and language, and short-term auditory training. Our results suggest that the incoming stimulus stream is constantly being monitored, even when the stimulus is physically invariant and attention is directed elsewhere, to augment the neural response to the most statistically salient features of the ongoing stimulus stream. These real-time transformations, which may subserve humans'' strong disposition for grouping auditory objects, likely reflect a mix of local processes and corticofugal modulation arising from statistical regularities and the influences of expectation. Our results contribute to our understanding of the biological basis of statistical learning and initiate a new investigational approach relating to the time-course of subcortical plasticity. Although the reported time-dependent enhancements are believed to reflect universal neurophysiological processes, future experiments utilizing a larger array of stimuli are needed to establish the generalizability of our findings.