How voluntary actions modulate time perception

Distortions of time perception are generally explained either by variations in the rate of pacing signals of an “internal clock”, or by lag-adaptation mechanisms that recalibrate the perceived time of one event relative to another. This study compares these accounts directly for one temporal illusion: the subjective compression of the interval between voluntary actions and their effects, known as ‘intentional binding’. Participants discriminated whether two cutaneous stimuli presented after voluntary or passive movements were simultaneous or successive. In other trials, they judged the temporal interval between their movement and an ensuing tone. Temporal discrimination was impaired following voluntary movements compared to passive movements early in the action-tone interval. In a control experiment, active movements without subsequent tones produced no impairment in temporal discrimination. These results suggest that voluntary actions transiently slow down an internal clock during the action-effect interval. This in turn leads to intentional binding, and links the effects of voluntary actions to the self

SNLS: Supernova Rise Times from the SNLS Sample

International audienceType Ia supernovae (SNe Ia) provide the most direct evidence for the acceleration of the Universe. This evidence relies on a comparison between the luminosities of distant and nearby SNe Ia, and hence is potentially sensitive to any evolution in the mean lightcurve properties between these two samples. One method for testing for the presence of such effects is to measure and compare the rise time, which is the time between explosion and maximum luminosity, of the two samples. The Supernova Legacy Survey provides an excellent data sample for the analysis of this issue, since it's 'rolling search' nature yields lightcurves which are well sampled prior to maximum light. Here we discuss measurements of the rise time from SNLS data and what they can tell us about evolutionary effects

Mechanisms of GnRH-Induced Extracellular Signal-Regulated Kinase Nuclear Localization

Gonadotropin-releasing hormone receptors (GnRHR) mediate activation and nuclear translocation of the extracellular signal regulated kinases 1 and 2 (ERK) by phosphorylation on the TEY motif. This is necessary for GnRH to initiate transcriptional programmes controlling fertility, but mechanisms that govern ERK targeting are unclear. Using automated microscopy to explore ERK regulation in single cells, we find that GnRHR activation induces marked redistribution of ERK to the nucleus and that this effect can be uncoupled from the level of TEY phosphorylation of ERK. Thus, 5 min stimulation with 100 nM GnRH increased phospho-ERK levels (from 89 ± 34 to 555 ± 45 arbitrary fluorescence units) and increased the nuclear:cytoplasmic (N:C) ERK ratio (from 1.36 ± 0.06 to 2.16 ± 0.05) in the whole cell population, but it also significantly increased N:C ERK in cells binned according to phospho-ERK levels. This phosphorylation unattributable component of the ERK translocation response occurs at a broad range of GnRHR expression levels, in the presence of tyrosine phosphatase and protein synthesis inhibitors, and in ERK mutants unable to undergo catalytic activation. It also occurred in mutants incapable of binding the DEF (docking site for ERK, F/Y-X-F/Y-P) domains found in many ERK binding partners. It was however, reduced by MEK or PKC inhibition and by mutations preventing TEY phosphorylation or that abrogate ERK binding to D (docking) domain partners. We therefore show that TEY phosphorylation of ERK is necessary, but not sufficient for the full nuclear localization response. We further show that this "phosphorylation unattributable" component of GnRH-mediated ERK nuclear translocation requires both PKC activity and association with partner proteins via the D-domain