The role of the glucocorticoid receptor gene (NR3C1) for the processing of aversive stimuli.

The glucocorticoid receptor (GR) is a crucial component of the hypothalamus-pituitary-adrenal (HPA) axis and as such a part of the stress response system. An impairment of the GR not only alters the level of glucocorticoids, but also modulates cognitive functions and the processing of emotional stimuli. We tested the effects of functional polymorphisms of the GR-encoding gene (NR3C1) on the processing of emotional stimuli on a basal level. In a sample of n=182 participants, we found a haplotype (NR3C1-CTGGACA) to modulate the performance in an emotional reaction time task. Compared to non-carriers, participants who carried the haplotype were quicker to react after aversive stimuli had been presented. In contrast, the presence of the haplotype had no effect on the processing of neutral stimuli. We conclude that properties of the glucocorticoid receptor contribute to the processing of emotional stimuli and influence the intensity of their processing even in the absence of acute stressors.

The negative priming paradigm: An update and implications for selective attention.

Negative Priming (NP) is an influential paradigm in cognitive psychology that was originally developed to measure attentional selection. Yet, up to the mid-1990s, a large number of experimental reports questioned whether the NP effect is based on attentional inhibition and/or episodic retrieval processes. In this review, we summarize findings since the mid-1990s and discuss new and old theoretical approaches to Negative Priming. We conclude that more than one process contributes to NP and that future research should analyze the conditions under which a particular process contributes to NP. Moreover, we argue that the paradigm--although it does not measure a single cognitive process alone--is still a useful tool for understanding selection in cognition. In fact, it might be a virtue of the paradigm that several cognitive processes work here together as selection in nonexperimental contexts is surely a multidimensional process. From this perspective, research on NP is relevant for all research fields analyzing selection. We therefore close our review by discussing the implications of the new evidence on NP for theories of selective attention.

Individual response speed is modulated by variants of the gene encoding the alpha 4 sub-unit of the nicotinic acetylcholine receptor (CHRNA4).

Acetylcholine (ACh) is a known modulator of several domains of cognition, among them attention, memory and learning. The neurotransmitter also influences the speed of information processing, particularly the detection of targets and the selection of suitable responses. We examined the effect of the rs1044396 (C/T) polymorphism of the gene encoding the nicotinic acetylcholine receptor α4-subunit (CHRNA4) on response speed and selective visual attention. To this end, we administered a Stroop task, a Negative priming task and an exogenous Posner-Cuing task to healthy participants (n = 157). We found that the CHRNA4 rs1044396 polymorphism modulated the average reaction times (RTs) across all three tasks. Dependent on the C allele dosage, the RTs linearly increased. Homozygous T allele carriers were always fastest, while homozygous C allele carriers were always slowest. We did not observe effects of this polymorphism on selective attention. In sum, we conclude that naturally occurring variations within the cholinergic system influence an important factor of information processing. This effect might possibly be produced by the neuromodulator system rather than the deterministic system of cortical ACh.

Genes of the dopaminergic system selectively modulate top-down but not bottom-up attention.

Cognitive performance is modulated by the neurotransmitter dopamine (DA). Recently, it has been proposed that DA has a strong impact on top-down but not on bottom-up selective visual attention. We tested this assumption by analyzing the influence of two gene variants of the dopaminergic system. Both the catechol O-methyltransferase (COMT) protein and the dopamine transporter (DAT) protein are crucial for the degradation and inactivation of DA. These metabolizing proteins modulate the availability of DA, especially in the prefrontal cortex and basal ganglia. The functional COMT Val158Met polymorphism of the COMT gene represents two coding variants, valine and methionine. In Met allele carriers, the COMT activity is reduced three- to fourfold. A variable number of tandem repeats (VNTR) polymorphism exists in the DAT1 gene, which encodes DAT. The DAT density was reported to be about 50% higher for the DAT1 10-repeat than the DAT1 9-repeat allele. We assessed attention via two experimental tasks that predominantly measure either top-down processing (the Stroop task) or bottom-up processing (the Posner-Cuing task). Carriers of the Met allele of the COMT Val158Met polymorphism displayed better performance in the Stroop task, but did not outperform the other participants in the Posner-Cuing task. The same result was noted for carriers of the DAT1 10-repeat allele. From these findings, we suggest that normal variations of the dopaminergic system impact more strongly on top-down than on bottom-up attention.

Elevated social stress levels and depressive symptoms in primary hyperhidrosis.

Primary hyperhidrosis is defined as excessive sweating of certain body areas without physiological reasons. Hyperhidrotic individuals report a high psychological strain and an impairment of their quality of life. Thus, the aim of the study is to investigate the relation between hyperhidrosis and different psychological as well as physiological aspects of chronic stress as a co-factor for the etiology of depression. In this study, forty hyperhidrotic subjects were compared to forty age- and sex-matched healthy control subjects. The Trier Inventory of Chronic Stress ('Trierer Inventar zum chronischen Stress': TICS), the Beck Depression Inventory (BDI-II) and the Screening for Somatoform Disorders (SOMS-2) were used to examine the correlation between primary hyperhidrosis and stress as well as accompanying depressive and somatic symptoms. The cortisol awakening response of each subject was analyzed as a physiological stress correlate. In hyperhidrotics, we found a significant lack of social recognition as well as significantly more depressive symptoms compared to the control subjects. A subgroup of patients with axillary hyperhidrosis had the highest impact on these increased issues of chronic stress, pointing to a higher embarrassment in these subjects. Especially in social situations, hyperhidrotics showed higher stress levels, whereby a vicious circle of stress and sweating is triggered. However, the cortisol awakening response did not significantly differ between hyperhidrotics and controls. Moreover, affected persons suffer from more depressive symptoms, which may be caused by feelings of shame and a lack of self-confidence. This initial study provides an impetus for further investigation to reveal a causative relationship between hyperhidrosis and its psychological concomitants.

Auditory distractor processing in sequential selection tasks.

In this review, we analyze the cognitive processes contributing to selection in audition. In particular, we focus on the processing of auditory distractors in sequential selection paradigms in which target stimuli are accompanied by distractors. We review the evidence from two established tasks, namely the auditory negative priming and the auditory distractor-response binding task, and discuss the cognitive mechanisms contributing to the results typically observed in these tasks. In fact, several processes have been suggested as to explain how distractors are processed and handled in audition; that is, auditory distractors can be inhibited, encoded with a do-not-respond-tag, integrated into a stimulus-response episode containing the response to the target, or upheld in working memory and matched/mismatched with the following distractor. In addition, variables possibly modulating these cognitive processes are discussed. Finally, auditory distractor processing is compared with distractor processing in vision.