Temporal dynamics

We combined a prototypical exogenous cuing procedure with rapid serial visual presentation (RSVP) to provide a precise characterization of the temporal dynamics of reflexive attention shifts. The novel paradigm thus created has several useful properties, most notably that the physical presentation of the target is neither an onset nor a unique event and that temporal precision is provided without the requirement for a speeded response. A biphasic pattern was observed, with early benefits followed by later costs (inhibition of return) at the cued location relative to the uncued location. The finding of inhibition of return in this paradigm disproves the assertion that inhibition of return is merely a reluctance to respond in the target's direction. It may be partly that, but encoding mechanisms linked to attention must also be involved.

Hippocampal plasticity and mnemonic processing exhibit a striking time-of-day dependence and likely implicate a temporally structured replay of memory traces. Molecular mechanisms fulfilling the requirements of sensing time and capturing time-related information are coded in dynamics of so-called clock genes and their protein products, first discovered and described in the hypothalamic suprachiasmatic nucleus. Using real-time PCR and immunohistochemical analyses, we show that in wildtype mice core clock components (mPer1/PER1, mPer2/PER2, mCry1/CRY1, mCry2/CRY2, mClock/CLOCK, mBmal1/BMAL1) are expressed in neurons of all subregions of the hippocampus in a time-locked fashion over a 24-h (diurnal) day/night cycle. Temporal profiling of these transcriptional regulators reveals distinct and parallel peaks, at times when memory traces are usually formed and/or consolidated. The coordinated rhythmic expression of hippocampal clock gene expression is greatly disordered in mice deficient for the clock gene mPer1, a key player implicated in both, maintenance and adaptative plasticity of circadian clocks. Moreover, Per1-knockout animals are severely handicapped in a hippocampus-dependent long-term spatial learning paradigm. We propose that the dynamics of hippocampal clock gene expression imprint a temporal structure on memory processing and shape at the same time the efficacy of behavioral learning. © 2009 Wiley-Liss, Inc.

Costimulation through the inducible costimulator (ICOS) and its ligand (ICOSL) is essential for T cell-dependent B cell responses, but the cellular and temporal dynamics underlying its in vivo effects are poorly defined. Here we have shown that Icosl(-/-) and Icos(-/-) mice had similar phenotypes and that ICOS-ICOSL costimulation modulated the early but not late phases of IgG1 affinity maturation. Exploiting the adoptive transfer of T or B cells from primed Icosl(-/-) mice, we provided genetic evidence that costimulation through ICOSL was essential for primary but not secondary helper T cell responses and for the control of both T and B cell activities, resulting in T cell-dependent IgG1 production.

The western corn rootworm Diabrotica virgifera virgifera LeConte (Col.:Chrysomelidae) (D.v.v.) is one of the most important maize pests in North America. Ever since its invasion into Europe and its detection near Belgrade airport by BACA in 1993 it quickly spread all over southeastern Europe and is now advancing towards central Europe. Up until summer 2004 considered free of D.v.v., Germany is, with the exception of its northern and northeastern borders, surrounded by countries with proven D.v.v. infestations. In addition to simultaneous spot introductions by airplanes, three main routes for terrestrial introduction into Germany are likely: 1. from south to north via Lombardy (Italy) through Switzerland to the State of Baden-Wuerttemberg in the southwest; 2. from south east to northwest via Croatia, Slovenia, Austria into the State of Bavaria; and 3. from Belgium and the Netherlands in southeasterly direction to the state of Northrhine-Westfalia. From these, progress of D.v.v. along...

Past research on automatic facial expression analysis has focused mostly on the recognition of prototypic expressions of discrete emotions rather than on the analysis of dynamic changes over time, although the importance of temporal dynamics of facial expressions for interpretation of the observed facial behavior has been acknowledged for over 20 years. For instance, it has been shown that the temporal dynamics of spontaneous and volitional smiles are fundamentally different from each other. In this work, we argue ...