Typologies of attentional networks

Attention is a central theme in cognitive science - it exemplifies the links between the brain and behaviour, and binds psychology to the techniques of neuroscience. A visionary model suggested by Michael Posner described attention as a set of independent control networks. This challenged the previously held view of attention as a uniform concept. The idea that disparate attentional networks correlate with discrete neural circuitry and can be influenced by focal brain injuries, mental state and specific drugs has since been supported by converging data from several modern methodologies. Given the recent explosion in empirical data, attentional typologies provide powerful conceptual tools with which to contextualize and integrate these findings.     

Subanesthetic ketamine reverses neuronal and astroglial metabolic activity deficits in a social defeat model of depression

Depression is one of the most debilitating neuropsychiatric disorders. Most of the current antidepressants have long remission time and low recovery rate. This study explores the impact of ketamine on neuronal and astroglial metabolic activity in prefrontal cortex in a social defeat (SD) model of depression. C57BL/6 mice were subjected to a social defeat paradigm for 5 min a day for 10 consecutive days. Ketamine (10 mg/kg, intraperitoneal) was administered to mice for two consecutive days following the last defeat stress. Mice were infused with [1,6‐¹³C₂]glucose or [2‐¹³C]acetate to assess neuronal and astroglial metabolic activity, respectively, together with proton‐observed carbon‐edited nuclear magnetic resonance spectroscopy in prefrontal cortex tissue extract. The ¹³C labeling of amino acids from glucose and acetate was decreased in SD mice. Ketamine treatment in SD mice restored sucrose preference, social interaction and immobility time to control values. Acute subanesthetic ketamine restored the ¹³C labeling of brain amino acids from glucose as well as acetate in SD mice to the respective control values, suggesting that rates of neuronal and astroglial tricarboxylic acid (TCA) cycle and neurotransmitter cycling were re‐established to normal levels. The finding of improved energy metabolism in SD mice suggests that fast anti‐depressant action of ketamine is linked with improved neurotransmitter cycling.

     

Gender difference of unconscious attentional bias in high trait anxiety individuals

By combining binocular suppression technique and a probe detection paradigm, we investigated attentional bias to invisible stimuli and its gender difference in both high trait anxiety (HTA) and low trait anxiety (LTA) individuals. As an attentional cue, happy or fearful face pictures were presented to HTAs and LTAs for 800 ms either consciously or unconsciously (through binocular suppression). Participants were asked to judge the orientation of a gabor patch following the face pictures. Their performance was used to measure attentional effect induced by the cue. We found gender differences of attentional effect only in the unconscious condition with HTAs. Female HTAs exhibited difficulty in disengaging attention from the location where fearful faces were presented, while male HTAs showed attentional avoidance of it. Our results suggested that the failure to find attentional avoidance of threatening stimuli in many previous studies might be attributed to consciously presented stimuli and data analysis regardless of participants' gender. These findings also contributed to our understanding of gender difference in anxiety disorder.     

Game-based biofeedback for paediatric anxiety and depression

Twenty-four children and adolescents aged 9-17 who were referred for treatment for anxiety were assigned to either a game-based biofeedback group or a waiting list comparison group. The eight-session biofeedback intervention included psychoeducation, identification of triggers and signs of anxiety, and in vivo practice. The intervention used computer-based gaming technology to teach and practise relaxation. Analyses using ANCOVA revealed significant differences in post-test scores of anxiety and depression measures between the two groups. The intervention group reduced anxiety and depression scores on standardised tests. Findings suggest that biofeedback-assisted relaxation training can be useful in decreasing anxiety and depressive symptoms in anxious youths.     

Lack of neuropsychological deficits in generalized social phobia

There are relatively few existing studies examining neuropsychological functioning in social phobia (SP), which collectively yield mixed results. Interpretation of results is further complicated by a number of methodological inconsistencies across studies, including the examination of neuropsychological domains in relative isolation from one another. The present study utilized a broader collection of neuropsychological tests to assess nine domains of functioning in 25 individuals diagnosed with generalized SP and 25 nonpsychiatric controls (NC). A mixed ANOVA revealed neither a significant group by domain interaction, nor a significant main effect of group. Furthermore, no significant group differences emerged between the SP and NC groups within each specific neuropsychological domain. These findings suggest that underlying neuropsychological deficits are not likely to account for the information processing biases observed in the empirical literature, and appear to be consistent with current theoretical models which argue for the specificity of these biases to social information.     

Detecting anxiety and depression in general medical settings.

To aid general practitioners and other non-psychiatrists in the better recognition of mental illness short scales measuring anxiety and depression were derived by latent trait analysis from a standardised psychiatric research interview. Designed to be used by non-psychiatrists, they provide dimensional measures of the severity of each disorder. The full set of nine questions need to be administered only if there are positive answers to the first four. When assessed against the full set of 60 questions contained in the psychiatric assessment schedule they had a specificity of 91% and a sensitivity of 86%. The scales would be used by non-psychiatrists in clinical investigations and possibly also by medical students to familiarise them with the common forms of psychiatric illness, which are often unrecognised in general medical settings.     

Involvement of melanocortin-4 receptor in anxiety and depression

The melanocortins, which are derived from proopiomelanocortin, have a variety of physiological functions mediated membrane surface receptors. To date, five subtypes have been cloned. With the cloning of melanocortin receptors, studies with genetic models, and development of selective compounds, the physiological roles of the five melanocortin receptors have begun to be understood. The melanocortin-4 receptor (MC4R), which is predominantly expressed in the central nervous system, has in particular become the focus of much attention in recent years because of the critical roles it plays in a wide range of functions, including feeding, sexual behavior, and stress. Recent development of selective antagonists for the MC4R has provided pharmacological evidence that blockade of MC4R could be a useful way of alleviating numerous conditions such as anxiety/depression, pain, and addiction to drugs of abuse.     

Trust transitivity in social networks

Non-centralized recommendation-based decision making is a central feature of several social and technological processes, such as market dynamics, peer-to-peer file-sharing and the web of trust of digital certification. We investigate the properties of trust propagation on networks, based on a simple metric of trust transitivity. We investigate analytically the percolation properties of trust transitivity in random networks with arbitrary in/out-degree distributions, and compare with numerical realizations. We find that the existence of a non-zero fraction of absolute trust (i.e. entirely confident trust) is a requirement for the viability of global trust propagation in large systems: The average pair-wise trust is marked by a discontinuous transition at a specific fraction of absolute trust, below which it vanishes. Furthermore, we perform an extensive analysis of the Pretty Good Privacy (PGP) web of trust, in view of the concepts introduced. We compare different scenarios of trust distribution: community- and authority-centered. We find that these scenarios lead to sharply different patterns of trust propagation, due to the segregation of authority hubs and densely-connected communities. While the authority-centered scenario is more efficient, and leads to higher average trust values, it favours weakly-connected "fringe" nodes, which are directly trusted by authorities. The community-centered scheme, on the other hand, favours nodes with intermediate in/out-degrees, in detriment of the authorities and its "fringe" peers.     

Detecting social transmission in networks

In recent years researchers have drawn attention to a need for new methods with which to identify the spread of behavioural innovations through social transmission in animal populations. Network-based analyses seek to recognise diffusions mediated by social learning by detecting a correspondence between patterns of association and the flow of information through groups. Here we introduce a new order of acquisition diffusion analysis (OADA) and develop established time of acquisition diffusion analysis (TADA) methods further. Through simulation we compare the merits of these and other approaches, demonstrating that OADA and TADA have greater power and lower Type I error rates than available alternatives, and specifying when each approach should be deployed. We illustrate the new methods by applying them to reanalyse an established dataset corresponding to the diffusion of foraging innovations in starlings, where OADA and TADA detect social transmission that hitherto had been missed. The methods are potentially widely applicable by researchers wishing to detect social learning in natural and captive populations of animals, and to facilitate this we provide code to implement OADA and TADA in the statistical package R.     

Assortative interactions and social networks in fish

The mechanisms underpinning the structure of social networks in multiple fish populations were investigated. To our knowledge this is the first study to provide replication of social networks and therefore probably the first that allows general conclusions to be drawn. The social networks were all found to have a non-random structure and exhibited social cliquishness. A number of factors were observed to contribute to this structuring. Firstly, social network structure was influenced by body length and shoaling tendency, with individuals interacting more frequently with conspecifics of similar body length and shoaling tendency. Secondly, individuals with many social contacts were found to interact with each other more often than with other conspecifics, a phenomenon known as a positive degree correlation. Finally, repeated interactions between pairs of individuals occurred within the networks more often than expected by random interactions. The observed network structures will have ecological and evolutionary implications. For example, the occurrence of positive degree correlations suggests the possibility that pathogens and information (that are socially transmitted) could spread very fast within the populations. Furthermore, the occurrence of repeated interactions between pairs of individuals fulfils an important pre-requisite for the evolution of reciprocal altruism.     

Men's social networks and contraception in Ghana

In this paper, longitudinal data from northern Ghana is used to assess the effects of encouragement to use family planning that men receive from their personal network partners on the adoption of modern contraception by their wives. The study tests a conceptual model that, in addition to the effect of men's network encouragement, incorporates the effect of encouragement to use family planning that women receive from their respective network partners and the effect of spousal communication on reproductive matters and approval of family planning. Results show that encouragement received by men from their social networks significantly increases the likelihood of subsequent contraceptive use by their wives but this effect operates primarily by galvanizing spousal communication on reproductive matters. The effect of encouragement received by women from their respective network partners is largely independent from the effect of male network encouragement but it influences contraceptive adoption both directly and through spousal communication.     

Association of tryptophan hydroxylase gene polymorphism with depression, anxiety and comorbid depression and anxiety in a population-based sample of postpartum Taiwanese women

Depression and anxiety disorders often coexist clinically and both are known to have a genetic basis, but the mode of inheritance is too complicated to be determined so far. Serotonin is the biogenic amine neurotransmitter most commonly associated with depression and anxiety. Since tryptophan hydroxylase (TPH1) is the rate-limiting enzyme in serotonin biosynthesis, its role in the pathophysiology of these psychiatric diseases has been intensively studied. In this study, we examined whether polymorphism of the TPH1 gene is related to the etiology of major depression, anxiety and comorbid depression and anxiety. Five single nucleoside polymorphisms of the TPH1 gene were studied in a population-based sample of postpartum Taiwanese women consisting of 120 subjects with depression or/and anxiety and 86 matched normal controls. A significant difference (P = 0.0107) in genotype frequency for the T27224C polymorphism was found between the comorbid and normal groups, and risk analysis showed that the C allele conferred a strong protective effect (odds ratio = 0.27; 95% confident interval = 0.11-0.7). Three-allele haplotypes involving T27224C polymorphism were constructed and haplotype associations between particular haplotype combinations and various diseases identified. However, the associations were weak and the overall haplotype frequency profiles in all groups were similar. The results suggest that depression, anxiety, and comorbid depression and anxiety disorders may have related etiologies. In addition, this study suggests that the TPH1 gene might play a role in the pathogenesis of these closely related disorders.     

The complex roles of neurosteroids in depression and anxiety disorders

The role of neurosteroids in neuropsychiatric disorders has been thoroughly investigated in many research studies that have stressed their significant pathophysiological function in neuropsychiatry. In this review, we will focus mainly on the steroids active on the GABA(A) receptors studied in anxiety and depression. The aim is to discuss the controversial results reported in research on anxiety and depressive disorders. We suggest the combined use of biological parameters linked to psychopathological dimensions to make more homogeneous diagnoses and to develop more precise therapies for the treatment of depression and anxiety disorders. We discuss the role of neurosteroids in the pathophysiology and therapy of anxiety and depression. Finally, we consider the possibility of using quantification of mRNA expression of steroidogenic enzymes from peripheral sources in neuropsychiatry.     

The effect of insomnia on changes in anxiety,depression, and social function after a transdiagnostic treatment targeting excessive worry

Sleep and Biological Rhythms - The present study examined whether improvements in insomnia affect symptoms of worry, anxiety, depression, and impaired social functioning after transdiagnostic...     

Hypothesis testing in animal social networks

Behavioural ecologists are increasingly using social network analysis to describe the social organisation of animal populations and to test hypotheses. However, the statistical analysis of network data presents a number of challenges. In particular the non-independent nature of the data violates the assumptions of many common statistical approaches. In our opinion there is currently confusion and uncertainty amongst behavioural ecologists concerning the potential pitfalls when hypotheses testing using social network data. Here we review what we consider to be key considerations associated with the analysis of animal social networks and provide a practical guide to the use of null models based on randomisation to control for structure and non-independence in the data.     

Threshold learning dynamics in social networks

Social learning is defined as the ability of a population to aggregate information, a process which must crucially depend on the mechanisms of social interaction. Consumers choosing which product to buy, or voters deciding which option to take with respect to an important issue, typically confront external signals to the information gathered from their contacts. Economic models typically predict that correct social learning occurs in large populations unless some individuals display unbounded influence. We challenge this conclusion by showing that an intuitive threshold process of individual adjustment does not always lead to such social learning. We find, specifically, that three generic regimes exist separated by sharp discontinuous transitions. And only in one of them, where the threshold is within a suitable intermediate range, the population learns the correct information. In the other two, where the threshold is either too high or too low, the system either freezes or enters into persistent flux, respectively. These regimes are generally observed in different social networks (both complex or regular), but limited interaction is found to promote correct learning by enlarging the parameter region where it occurs.