Evidence from reaction times for an anticipatory process in symbolic delayed matching-to-sample

It was predicted that a delay between sample ofset and comparison onset in symbolic delayed matching-to-sample (DMTS) would allow time for the anticipatory retrieval of the correct comparison so that the match/no match status of the presented comparison could be decided more swiftly. The relation between delay and reaction time (RT) was explored in participants after they had been similarly tested, as a control, on identity DMTS using the same stimuli. In most participants there was the predicted inverse relation between delay and RT in symbolic DMTS, but no such relation in identity DMTS. Subsequently an arithmetic test, designed to allow a simple calculation before or after presentation of the comparison, was used to demonstrate an analogous effect of a delay on RT

Related to Anxiety: Arbitrarily Applicable Relational Responding and Experimental Psychopathology Research on Fear and Avoidance

Humans have an unparalleled ability to engage in arbitrarily applicable relational responding (AARR). One of the consequences of this ability to spontaneously combine and relate events from the past, present, and future may, in fact, be a propensity to suffer. For instance, maladaptive fear and avoidance of remote or derived threats may actually perpetuate anxiety. In this narrative review, we consider contemporary AARR research on fear and avoidance as it relates to anxiety. We first describe laboratory-based research on the emergent spread of fear- and avoidance-eliciting functions in humans. Next, we consider the validity of AARR research on fear and avoidance and address the therapeutic implications of the work. Finally, we outline challenges and opportunities for a greater synthesis between behavior analysis research on AARR and experimental psychopathology

More on how and why : a response to commentaries

We are grateful to the commentators for taking the time to respond to our article. Too many interesting and important points have been raised for us to tackle them all in this response, and so in the below we have sought to draw out the major themes. These include problems with both the term ‘ultimate causation’ and the proximate-ultimate causation dichotomy more generally, clarification of the meaning of reciprocal causation, discussion of issues related to the nature of development and phenotypic plasticity and their roles in evolution, and consideration of the need for an extended evolutionary synthesis.Publisher PDFPeer reviewe

Variability of Inducible Expression across the Hematopoietic System of Tetracycline Transactivator Transgenic Mice

The tetracycline (tet)-regulated expression system allows for the inducible overexpression of protein-coding genes, or inducible gene knockdown based on expression of short hairpin RNAs (shRNAs). The system is widely used in mice, however it requires robust expression of a tet transactivator protein (tTA or rtTA) in the cell type of interest. Here we used an in vivo tet-regulated fluorescent reporter approach to characterise inducible gene/shRNA expression across a range of hematopoietic cell types of several commonly used transgenic tet transactivator mouse strains. We find that even in strains where the tet transactivator is expressed from a nominally ubiquitous promoter, the efficiency of tet-regulated expression can be highly variable between hematopoietic lineages and between differentiation stages within a lineage. In some cases tet-regulated reporter expression differs markedly between cells within a discrete, immunophenotypically defined population, suggesting mosaic transactivator expression. A recently developed CAG-rtTA3 transgenic mouse displays intense and efficient reporter expression in most blood cell types, establishing this strain as a highly effective tool for probing hematopoietic development and disease. These findings have important implications for interpreting tet-regulated hematopoietic phenotypes in mice, and identify mouse strains that provide optimal tet-regulated expression in particular hematopoietic progenitor cell types and mature blood lineages

Tissue-specific and reversible RNA interference in transgenic mice

Genetically engineered mice provide powerful tools for understanding mammalian gene function. These models traditionally rely on gene overexpression from transgenes or targeted, irreversible gene mutation. By adapting the tetracycline (tet)-responsive system previously used for gene overexpression, we have developed a simple transgenic system to reversibly control endogenous gene expression using RNA interference (RNAi) in mice. Transgenic mice harboring a tet-responsive RNA polymerase II promoter driving a microRNA-based short hairpin RNA targeting the tumor suppressor Trp53 reversibly express short hairpin RNA when crossed with existing mouse strains expressing general or tissue-specific 'tet-on' or 'tet-off' transactivators. Reversible Trp53 knockdown can be achieved in several tissues, and restoring Trp53 expression in lymphomas whose development is promoted by Trp53 knockdown leads to tumor regression. By leaving the target gene unaltered, this approach permits tissue-specific, reversible regulation of endogenous gene expression in vivo, with potential broad application in basic biology and drug target validation