Cell death plays a critical role in the generation of an effective immune system. During maturation T lymphocytes are generated, censored and eliminated in the thymus. These events are temporally associated with developmental changes in the levels of transcription factors including NFAT. The NFAT transcription factor (nuclear factor of activated T cells) is implicated in the regulation of T-lymphocyte proliferation and transcriptional activation of genes encoding lymphokines. It has been demonstrated that discontinuities in the inducibility of NFAT and AP-1 transcription factors occur during transition of immature thymocytes into cortical thymocytes which are eliminated by apoptosis. To understand the molecular basis of these developmental intrathymic changes, we studied DNA-binding activities of transcription factors during dexamethasone-induced apoptosis of immature thymocytes. We observed a specific loss of NFAT DNA-binding activity after dexamethasone treatment. It correlated with a selective disappearance of one out of two AP-1 complexes. Our data suggest that NFAT complex is a possible target in dexamethasone-induced apoptosis.

Previous studies indicate that there are at least two levels of temporal processing: the sub- and supra-second domains. The relationship between these domains remains unclear. The aim of this study was to test whether performance on the sub-second level is related to that on the supra-second one, or whether these two domains operate independently. Participants were 118 healthy adults (mean age = 23 years). The sub-second level was studied with a temporal-order judgment task and indexed by the Temporal Order Threshold (TOT), on which lower values corresponded to better performance. On the basis of TOT results, the initial sample was classified into two groups characterized by either higher temporal efficiency (HTE) or lower temporal efficiency (LTE). Next, the efficiency of performance on the supra-second level was studied in these two groups using the subjective accentuation task, in which participants listened to monotonous sequences of beats and were asked to mentally accentuate every n-th beat to create individual rhythmic patterns. The extent of temporal integration was assessed on the basis of the number of beats being united and better performance corresponded to longer units. The novel results are differences between groups in this temporal integration. The HTE group integrated beats in significantly longer units than did the LTE group. Moreover, for tasks with higher mental load, the HTE group relied more on a constant time strategy, whereas the LTE group relied more on mental counting, probably because of less efficient temporal integration. These findings provide insight into associations between sub- and supra-second levels of processing and point to a common time keeping system, which is active independently of temporal domain.

Planning is a fundamental mental ability related to executive functions. It allows to select, order and execute subgoals to achieve a goal. Studies have indicated that these processes are characterised by a specific temporal dynamics reflected in temporal information processing (TIP) in some tens of millisecond domain. Both planning and TIP decline with age but the underlying mechanisms are unclear. The novel value of the present study was to examine these mechanisms in young (n = 110) and elderly (n = 91) participants in Tower of London task, considering two structural properties of problems: search depth related to static maintenance in working memory, and goal ambiguity reflecting dynamic cognitive flexibility. Results revealed that TIP predicted planning accuracy both directly and indirectly (via preplanning) but only in young participants in problems characterised by high goal ambiguity. Better planning is related to longer preplanning and more efficient TIP. This result demonstrates for the first time age-related differences in the contribution of TIP to planning. In young participants TIP contributed to dynamic cognitive flexibility, but not to static maintenance processes. In elderly such relation was not observed probably because the deficient planning might depend on working memory maintenance rather than on cognitive flexibility.