Increased parietal activity after training of interference control

Recent studies suggest that computerized cognitive training leads to improved performance in related but untrained tasks (i.e. transfer effects). However, most study designs prevent disentangling which of the task components are necessary for transfer. In the current study, we examined whether training on two variants of the adaptive dual n-back task would affect untrained task performance and the corresponding electrophysiological event-related potentials (ERPs). Forty three healthy young adults were trained for three weeks with a high or low interference training variant of the dual n-back task, or they were assigned to a passive control group. While n-back training with high interference led to partial improvements in the Attention Network Test (ANT), we did not find transfer to measures of working memory and fluid intelligence. ERP analysis in the n-back task and the ANT indicated overlapping processes in the P3 time range. Moreover, in the ANT, we detected increased parietal activity for the interference training group alone. In contrast, we did not find electrophysiological differences between the low interference training and the control group. These findings suggest that training on an interference control task leads to higher electrophysiological activity in the parietal cortex, which may be related to improvements in processing speed, attentional control, or both.

The bivalency effect represents an interference-triggered adjustment of cognitive control: an ERP study

When bivalent stimuli (i.e., stimuli with relevant features for two different tasks) occur occasionally among univalent stimuli, performance is slowed on subsequent univalent stimuli even if they have no overlapping stimulus features. This finding has been labeled the bivalency effect. It indexes an adjustment of cognitive control, but the underlying mechanism is not well understood yet. The purpose of the present study was to shed light on this question, using event-related potentials. We used a paradigm requiring predictable alternations between three tasks, with bivalent stimuli occasionally occurring on one task. The results revealed that the bivalency effect elicited a sustained parietal positivity and a frontal negativity, a neural signature that is typical for control processes implemented to resolve interference. We suggest that the bivalency effect reflects interference, which may be caused by episodic context binding.

On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry

Stable carbon isotope analysis of methane (delta C-13 of CH4) on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography (GC) isotope ratio mass spectrometry (IRMS) coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton (Kr) can severely interfere during the mass spectrometric measurement, leading to significant biases in delta C-13 of CH4, if krypton is not sufficiently separated during the analysis. According to our experiments, the krypton interference is likely composed of two individual effects, with the lateral tailing of the doubly charged Kr-86 peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups. Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to result from scattered ions of singly charged krypton. The introduced bias in the measured isotope ratios is dependent on the chromatographic separation, the krypton-to-CH4 mixing ratio in the sample, the focusing of the mass spectrometer as well as the detector configuration and can amount to up to several per mil in delta C-13. Apart from technical solutions to avoid this interference, we present correction routines to a posteriori remove the bias.

RNA interference screening identifies a novel role for PCTK1/CDK16 in medulloblastoma with c-Myc amplification.

Medulloblastoma (MB) is the most common malignant brain tumor in children and is associated with a poor outcome. cMYC amplification characterizes a subgroup of MB with very poor prognosis. However, there exist so far no targeted therapies for the subgroup of MB with cMYC amplification. Here we used kinome-wide RNA interference screening to identify novel kinases that may be targeted to inhibit the proliferation of c-Myc-overexpressing MB. The RNAi screen identified a set of 5 genes that could be targeted to selectively impair the proliferation of c-Myc-overexpressing MB cell lines: AKAP12 (A-kinase anchor protein), CSNK1α1 (casein kinase 1, alpha 1), EPHA7 (EPH receptor A7) and PCTK1 (PCTAIRE protein kinase 1). When using RNAi and a pharmacological inhibitor selective for PCTK1, we could show that this kinase plays a crucial role in the proliferation of MB cell lines and the activation of the mammalian target of rapamycin (mTOR) pathway. In addition, pharmacological PCTK1 inhibition reduced the expression levels of c-Myc. Finally, targeting PCTK1 selectively impaired the tumor growth of c-Myc-overexpressing MB cells in vivo. Together our data uncover a novel and crucial role for PCTK1 in the proliferation and survival of MB characterized by cMYC amplification.

Ego depletion after social interference

The present study examines whether social interference (i.e., interference with one’s goal attainment by the bodily presence of others) depletes the limited resource of self-control strength. In an experimental laboratory study (N = 34), half the participants experienced social interference whereas the other half did not experience social interference by two confederates during a dexterity task. Afterwards, we measured participants’ momentary self-control strength applying a Stroop colour-naming task. In line with our prediction, participants’ performance in the Stroop task indicated that social interference reduced self-control strength. We discuss implications for crowding research and crowding in natural settings.