P S Y C H O L O G Y

A l t e r e d f r o n t a l c o r t i c a l v o l u m e a n d d e c i s i o n m a k i n g in a d o l e s c e n t c a n n a b i s u s e r s Anticipating future outcom es is central to decision making and a failure to consider long-term co n sequences may lead to impulsive choices. A dolescence is a vulnerable period during which underdeveloped prefrontal cortical system s may contribute to poor judgment, impulsive choices, and substance abuse. Conversely, substance abuse during this period may alter neural system s involved in decision making and lead to greater impulsivity. Although a broad neural network which supports decision making undergoes extensive change during adolescent development, one region that may be critical is the medial prefrontal cortex. Altered functional integrity of this region may be specifically related to reward perception, substance abuse, and dependence. In the present investigation, w e acquired structural m agnetic resonance im ages (MRI), using a 3T SiemensTrio scanner, from 18 cannabis abusing adolescents (CA; 2 female and 16 male subjects; m ean age, 17.7 years; range 16-19 years), and 18 healthy controls (HC; 6 female and 12 male subjects; m ean age, 17.2 years; range 16-19 years). In order to m easure medial orbital prefrontal cortex (moPFC) morphology related to su b stan c e ab u se and impulsivity, sem i autom ated cortical reconstruction and volumetric segm entation of MRIs w as performed with FreeSurfer. Impulsivity w as evaluated with the Barratt Impulsiveness Scale (BIS). J o h n C. C h u r c h w e ll1, M e lis s a L o p e z -L a r s o n 12 a n d D e b o r a h A . Y u r g e lu n -T o d d 1

Permutation testing made practical for functional magnetic resonance image analysis

We describe an efficient algorithm for the step-down permutation test, applied to the analysis of functional magnetic resonance images. The algorithm's time bound is nearly linear, making it feasible as an interactive tool. Results of the permutation test algorithm applied to data from a cognitive activation paradigm are compared with those of a standard parametric test corrected for multiple comparisons. The permutation test identifies more weakly activated voxels than the parametric test, always activates a superset of the voxels activated by this parametric method, almost always yields significance levels greater than or equal to those produced by the parametric method, and tends to enlarge activated clusters rather than adding isolated voxels. Our implementation of the permutation test is freely available as part of a widely distributed software package for analysis of functional brain images

Local brain connectivity and associations with gender and age

ABSTRACTRegional homogeneity measures synchrony of resting-state brain activity in neighboring voxels, or local connectivity. The effects of age and gender on local connectivity in healthy subjects are unknown. We performed regional homogeneity analyses on resting state BOLD time series data acquired from 58 normal, healthy participants, ranging in age from 11 to 35 (mean 18.1±5.0 years, 32 males). Regional homogeneity was found to be highest for gray matter, with brain regions within the default mode network having the highest local connectivity values. There was a general decrease in regional homogeneity with age with the greatest reduction seen in the anterior cingulate and temporal lobe. Greater female local connectivity in the right hippocampus and amygdala was also noted, regardless of age. These findings suggest that local connectivity at the millimeter scale decreases during development as longer connections are formed, and underscores the importance of examining gender differences in imaging studies of healthy and clinical populations

Lower Left Thalamic Myo-Inositol Levels Associated with Greater Cognitive Impulsivity in Marijuana-Dependent Young Men: Preliminary Spectroscopic Evidence at 4T

The effects of chronic marijuana (MRJ) use on neurochemistry are not well characterized. Previously, altered global myo-Inositol (mI) concentrations and distribution in white matter were associated with impulsivity and mood symptoms in young MRJ-dependent men. The objective of this study was to retrospectively examine previously collected data, to investigate the potential regional specificity of metabolite levels in brain regions densely packed with cannabinoid receptors. Spectra were acquired at 4.0 Tesla using 2D J-resolved proton magnetic resonance spectroscopic imaging (MRSI) to quantify the entire J-coupled spectral surface of metabolites from voxels in regions of interest. For the current regional spectral analyses, a 2D-JMRSI grid was positioned over the central axial slice and shifted in the x and y dimensions to optimally position voxels over regions containing thalamus, temporal lobe, and parieto-occipital cortex. MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity. Other regional analyses did not reveal any significant group differences. The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users. Furthermore, findings suggest that mI and the lThal uniquely contribute to elevated impulsivity

Functional connectivity during a social emotion task in adolescents and in adults

In this fMRI study we investigated functional connectivity between components of the mentalising system during a social emotion task, using psychophysiological interaction (PPI) analysis. Ten adults (22–32 years) and 18 adolescents (11–18 years) were scanned while thinking about scenarios in which a social or a basic emotion would be experienced. Unlike basic emotions (such as disgust and fear), social emotions (such as embarrassment and guilt) require the representation of another's mental states. In both adults and adolescents, an anterior rostral region of medial prefrontal cortex (arMPFC) involved in mentalising showed greater connectivity with the posterior superior temporal sulcus (pSTS) bordering on the temporo-parietal junction (TPJ) and with anterior temporal cortex (ATC) during social than during basic emotion. This result provides novel evidence that components of the mentalising system interact functionally during a social emotion task. Furthermore, functional connectivity differed between adolescence and adulthood. The adolescent group showed stronger connectivity between arMPFC and pSTS/TPJ during social relative to basic emotion than did the adult group, suggestive of developmental changes in functional integration within the mentalising system

Comparing the effectiveness of game literacy education and game coding education in improving problematic internet gaming

ObjectiveProblematic internet gaming by adolescents has been thought to be associated with low self-esteem, depression, anxiety, and attention problems. We hypothesized that both game literacy and coding education would effectively improve problematic internet use. However, game coding education would be more effective in enhancing self-esteem and social anxiety in adolescents than game literacy education.MethodsA total of 733 adolescent volunteers were included and randomly assigned to either the game coding education or game literacy education programs. Both programs consisted of eight sessions, each lasting 45 minutes, over four weeks. The coding education sessions included game planning and development lessons and allowed students to create the game’s characters, stages, and tutorials directly using Scratch, a free coding program. Game literacy education sessions included lessons on enjoying gaming with a healthy rationale and etiquette. Data on demographics, gaming patterns, and psychological status, including positive/negative perceptions of online games, depression, social anxiety, and self-esteem, were collected.ResultsBoth game coding and game literacy education significantly improved YIAS scores compared to baseline, and there was no significant difference in the YIAS scores between the two groups after the interventions. In the hierarchical logistic regression analysis of all participants, higher YIAS scores, stronger negative perceptions of gaming, and lower attention problem scores at baseline predicted lower levels of internet gaming addiction after interventions. In the hierarchical logistic regression analysis among individuals with game coding education, higher YIAS scores, stronger negative perceptions of gaming, lower attention problem scores, and higher self-esteem scores at baseline predicted lower levels of internet gaming addiction after intervention. In addition, game coding education greatly improved negative perceptions of games, self-esteem, and social anxiety compared to game literacy education.ConclusionBoth game literacy and game coding education effectively mitigate internet game addiction. However, game coding education effectively mitigated problematic internet gaming by improving negative perceptions of games, self-esteem, and social anxiety in adolescents. We found that the application of knowledge by students in creating their own games was more effective than simply developing a conceptual understanding of the games

Lynch Syndrome - Cancer Pathways, Heterogeneity and Immune Escape

Recent work has provided evidence for genetic and molecular heterogeneity in colorectal cancers (CRCs) arising in patients with Lynch syndrome (LS), dividing these into two groups: G1 and G2. In terms of mutation and gene expression profile, G1 CRCs bear resemblance to sporadic CRCs with microsatellite instability (MSI), whereas G2 CRCs are more similar to microsatellite stable CRCs. Here we review the current state of knowledge on pathways of precursor progression to CRC in LS and how these might tie in with the new findings. Immunotherapies are an active field of research for MSI cancers and their potential use for cancer therapy for both sporadic and LS MSI cancers is discussed

First-Episode Schizophrenic Psychosis Differs From First-Episode Affective Psychosis and Controls in P300 Amplitude Over Left Temporal Lobe

Background: Schizophrenia is associated with central (sagittal) midline reductions of the P300 cognitive event-related potential and topographic asymmetry of P300, with reduced left temporal voltage. This P300 asymmetry is, in turn, linked to tissue volume asymmetry in the posterior superior temporal gyrus. However, it is unknown whether P300 asymmetry is specific to schizophrenia and whether central and lateral P300 abnormalities are due to chronic morbidity, neuroleptic medication, and/or hospitalization, or whether they are present at the onset of illness. Methods: P300 was recorded in first-episode schizophrenia, first-episode affective psychosis, and control subjects (n=14 per group). Subjects silently counted rare (15%) target tones (1.5 kHz) among trains of standard tones (1.0 kHz). Averages were constructed from brain responses to target tones. Results: Peak amplitude of P300 and integrated voltage over 300 to 400 milliseconds were significantly different between first-episode schizophrenics and controls over the posterior sagittal midline of the head. First-episode schizophrenics displayed smaller amplitudes over the left temporal lobe than first-episode affective psychotics and controls, but the groups showed no differences over the right temporal lobe. Conclusions: Left-sided P300 abnormality in first-episode schizophrenia relative to first-episode affective psychosis and controls suggests that P300 asymmetry is specific to schizophrenic psychosis and present at initial hospitalization. This P300 asymmetry suggests left temporal lobe dysfunction at the onset of schizophrenia