Bernd Lachmann

Reduced grid-cell–like representations in adults at genetic risk for Alzheimer’s disease

Early signs of dementia There is currently no cure for Alzheimers disease. One of the reasons could be that interventions start too late, when there is already irreversible damage to the brain. Developing a biomarker that would help to effectively start therapy at very early stages of the disease is thus of high interest. Kunz et al. studied neural correlates of spatial navigation in the entorhinal cortex in control study participants and individuals at risk of developing Alzheimers. The at-risk group showed a different brain signal many decades before the onset of the disease, and they navigated differently in a virtual environment. Science, this issue p. 430 Individuals at risk of developing Alzheimer’s navigate differently in a virtual environment. Alzheimer’s disease (AD) manifests with memory loss and spatial disorientation. AD pathology starts in the entorhinal cortex, making it likely that local neural correlates of spatial navigation, particularly grid cells, are impaired. Grid-cell–like representations in humans can be measured using functional magnetic resonance imaging. We found that young adults at genetic risk for AD (APOE-ε4 carriers) exhibit reduced grid-cell–like representations and altered navigational behavior in a virtual arena. Both changes were associated with impaired spatial memory performance. Reduced grid-cell–like representations were also related to increased hippocampal activity, potentially reflecting compensatory mechanisms that prevent overt spatial memory impairment in APOE-ε4 carriers. Our results provide evidence of behaviorally relevant entorhinal dysfunction in humans at genetic risk for AD, decades before potential disease onset.

Assessing the function of the fronto-parietal attention network: insights from resting-state fMRI and the attentional network test.

In the recent past, various intrinsic connectivity networks (ICN) have been identified in the resting brain. It has been hypothesized that the fronto‐parietal ICN is involved in attentional processes. Evidence for this claim stems from task‐related activation studies that show a joint activation of the implicated brain regions during tasks that require sustained attention. In this study, we used functional magnetic resonance imaging (fMRI) to demonstrate that functional connectivity within the fronto‐parietal network at rest directly relates to attention. We applied graph theory to functional connectivity data from multiple regions of interest and tested for associations with behavioral measures of attention as provided by the attentional network test (ANT), which we acquired in a separate session outside the MRI environment. We found robust statistical associations with centrality measures of global and local connectivity of nodes within the network with the alerting and executive control subfunctions of attention. The results provide further evidence for the functional significance of ICN and the hypothesized role of the fronto‐parietal attention network. Hum Brain Mapp 35:1700–1709, 2014.

Attention Deficit/Hyperactivity Disorder is a Better Predictor for Problematic Internet use than Depression: Evidence from Germany

Objective: This study aims to address possible associations between excessive use of the Internet and ADHD and Depression. As most of the studies on this topic were conducted in Asia, the aim of this investigation is to review the literature on this subject from Germany and examine problematic Internet use for potential associations with the propensity for Depression and Attention Deficit/Hyperactivity Disorder (ADHD) in a new, distinct German sample. Methods: A review of the literature was conducted. Subsequently, a total of N = 895 healthy participants from Germany (413 males, 482 females) took part in a new study. Participants filled in questionnaires on their Internet usage, propensity for depression and ADHD. Results: The review of the literature revealed predominantly positive associations between problematic Internet use and depression, whereas only one study on the relationship between problematic Internet use and ADHD from Germany was found. The results from the current study showed that male participants had significantly higher scores on the Internet Addiction Test (IA-T) than female participants. Finally, the IA-T scores of the participants were linked to both the propensity for depression (r = .247, p < .01) and ADHD (r = .335, p < .01). This association was stronger for ADHD and in particular for the subscale “attention deficit”, as revealed by a post-hoc analysis. Conclusion: The results of this study are consistent with most of the research on this topic in other cultural circles and highlight the role of ADHD and depression when it comes to problematic Internet use. This study provides a basis for consideration about the clinical implications and treatment of comorbid problematic Internet use.

Recorded Behavior as a Valuable Resource for Diagnostics in Mobile Phone Addiction: Evidence from Psychoinformatics.

Psychologists and psychiatrists commonly rely on self-reports or interviews to diagnose or treat behavioral addictions. The present study introduces a novel source of data: recordings of the actual problem behavior under investigation. A total of N = 58 participants were asked to fill in a questionnaire measuring problematic mobile phone behavior featuring several questions on weekly phone usage. After filling in the questionnaire, all participants received an application to be installed on their smartphones, which recorded their phone usage for five weeks. The analyses revealed that weekly phone usage in hours was overestimated; in contrast, numbers of call and text message related variables were underestimated. Importantly, several associations between actual usage and being addicted to mobile phones could be derived exclusively from the recorded behavior, but not from self-report variables. The study demonstrates the potential benefit to include methods of psychoinformatics in the diagnosis and treatment of problematic mobile phone use.

The importance of analogue zeitgebers to reduce digital addictive tendencies in the 21st century

Analogue zeitgebers such as wristwatches and alarm clocks are essential for structuring everyday life. Since the dawn of the digital revolution – particularly since the advent of the smartphone – mobile phones have increasingly replaced analogue zeitgebers as a means of telling time. This functionality may prove problematic, in that it may contribute to the overuse of digital media (e.g. when checking the time turns into extended use of other smartphone utilities, including Internet-based applications). Of N = 3084 participants, 45% reported wearing a wristwatch and 67% used an analogue alarm clock. We observed that participants who reported using analogue zeitgebers used their mobile-/smartphone significantly less. Use of analogue zeitgebers may prove a practical tool for therapeutic and preventative interventions for problematic Internet use in an increasingly digital age.

Facebook usage on smartphones and gray matter volume of the nucleus accumbens

&NA; A recent study has implicated the nucleus accumbens of the ventral striatum in explaining why online‐users spend time on the social network platform Facebook. Here, higher activity of the nucleus accumbens was associated with gaining reputation on social media. In the present study, we touched a related research field. We recorded the actual Facebook usage of N = 62 participants on their smartphones over the course of five weeks and correlated summary measures of Facebook use with gray matter volume of the nucleus accumbens. It appeared, that in particular higher daily frequency of checking Facebook on the smartphone was robustly linked with smaller gray matter volumes of the nucleus accumbens. The present study gives additional support for the rewarding aspects of Facebook usage. Moreover, it shows the feasibility to include real life behavior variables in human neuroscientific research.

Life satisfaction and problematic Internet use: Evidence for gender specific effects.

The present study investigates, using a large sample (N=4852 participants; 51.71% males), how problematic Internet use (PIU) relates to general life satisfaction and distinct facets of everyday life such as job, leisure, and health. Data on Internet usage was gathered using a short form of the Young Internet Addiction Test. Life satisfaction was measured with standardized items taken from the socioeconomic panel (Germany). Highly significant associations were observed between PIU and the facets of life satisfaction, health and leisure. Of note, these associations between the mentioned facets of life satisfaction and PIU were significantly higher for females compared to males, although the reported total level of PIU was significantly lower for females. This suggests the presence of different thresholds for males and females with respect to negative effects on well-being due to PIU. The current study underlines the importance of including gender as a critical variable when investigating the association between life satisfaction and PIU.

Voxelwise eigenvector centrality mapping of the human functional connectome reveals an influence of the catechol-O-methyltransferase val158met polymorphism on the default mode and somatomotor network.

Functional connections between brain regions constitute the substrate of the human functional connectome, whose topography has been discussed as an endophenotype for psychiatric disorders. Genetic influences on the entire connectome, however, have been rarely investigated so far. We tested for connectome-wide influences of the val158met (rs4860) polymorphism on the catechol-O-methyltransferase (COMT) gene by applying formal network analysis and eigenvector centrality mapping on the voxel level to resting-state functional magnetic imaging data. This approach finds brain regions that are central in the network by aggregating local and global connectivity patterns, most importantly without the requirement to select regions or networks of interest. The COMT variant linked to high enzyme activity increased network centrality in distributed brain areas that are known to constitute the brain’s default mode network. Further results also indicated a COMT influence on areas implicated in the somatomotor network. These findings are in line with the polymorphism’s alleged role in cognitive processing and its role in psychotic disorders. The study is the first to demonstrate the influence of a functional and behaviorally relevant genetic variant on connectome-wide functional connectivity and is an important step toward establishing the functional connectome as an endophenotype for psychiatric and behavioral phenotypes.

Individual differences in implicit learning abilities and impulsive behavior in the context of Internet addiction and Internet Gaming Disorder under the consideration of gender

•Higher Internet addiction scores were linked to deficient implicit learning.•This association was found in two independent groups of male (excessive) gamers.•Online Gaming addiction was linked to higher risk-taking in healthy participants.•Implicit learning and risk-taking were assessed, using an experimental task.

The 2D:4D-Ratio and Neuroticism Revisited: Empirical Evidence from Germany and China

The 2D:4D-Ratio, as an indirect measure of the fetal testosterone to estradiol ratio, is potentially very important for understanding and explaining different personality traits. It was the aim of the present study to replicate the findings from Fink et al. (2004) about the relation between individual differences in 2D:4D-Ratios and the Five Factor Model in different cultural groups. Therefore a sample of n = 78 Chinese and n = 370 German participants was recruited. Every participant provided hand scans of both hands, from which 2D:4D-Ratios were computed. Moreover, all participants filled in the NEO Five Factor Inventory (NEO-FFI). Significant sex differences were found for ratios of both hands in the expected direction, with females showing higher ratios than males. With respect to links between personality and the digit ratio, a positive association was observed between 2D:4D-Ratio and Neuroticism in females, as shown in the earlier study. These findings were observed in both female subsamples from China and Germany, as well as in the full sample of participants. But in contrast to the results for the whole and the German female sample, where 2D:4D-Ratio of both hands were related to Neuroticism, in the Chinese female sample only left hand 2D:4D-Ratio was significantly and positively related to Neuroticism. There were no significant correlations found in any of the male samples. Thus, prenatal exposure to sex steroids appears to influence the personality factor Neuroticism in females specifically. This finding potentially has implications for mental health, as Neuroticism has been shown to be a risk factor for various forms of psychopathology.