Modulation of N400 in chronic non-fluent aphasia using low frequency Repetitive Transcranial Magnetic Stimulation (rTMS)

Low frequency Repetitive Transcranial Magnetic Stimulation (rTMS) has previously been applied to language homologues in non-fluent populations of persons with aphasia yielding significant improvements in behavioral language function up to 43 months post stimulation. The present study aimed to investigate the electrophysiological correlates associated with the application of rTMS through measurement of the semantic based N400 Event-related brain potentials (ERP) component. Low frequency (1 Hz) rTMS was applied to the anterior portion of the homologue to Broca’s area (pars triangularis), for 20 min per day for 10 days, using a stereotactic neuronavigational system. Twelve non-fluent persons with aphasia, 2-6 years post stroke were stimulated. Six participants were randomly assigned to receive real stimulation and six participants were randomly assigned to receive a blind sham control condition. ERP measures were recorded at baseline, 1 week and 2 months subsequent to stimulation. The findings demonstrate treatment related changes observed in the stimulation group when compared to the placebo control group at 2 months post stimulation indicating neuromodulation of N400 as a result of rTMS. No treatment related changes were identified in the stimulation group, when compared to the sham group from baseline to 1 week post stimulation. The electrophysiological results represent the capacity of rTMS to modulate neural language networks and measures of lexical-semantic function in participants with non-fluent aphasia and suggest that time may be an important factor in brain reorganization subsequent to rTMS.     

Do physical and relational aggression explain adolescents' friendship selection? The competing roles of network characteristics,gender, and social status

The role of physical and relational aggression in adolescents' friendship selection was examined in a longitudinal sample of 274 Chilean students from 5th and 6th grade followed over 1 year. Longitudinal social network modeling (SIENA) was used to study selection processes for aggression while influence processes were controlled for. Furthermore, the effects of network characteristics (i.e., reciprocity and transitivity), gender, and social status on friendship selection were examined. The starting assumption of this study was that selection effects based on aggression might have been overestimated in previous research as a result of failing to consider influence processes and alternative characteristics that steer friendship formation. The results show that selection effects of both physical and relational aggression disappeared when network effects, gender, and social status were taken into account. Particularly gender and perceived popularity appeared to be far more important determinants of friendship selection over time than aggression. Moreover, a peer influence effect was only found for relational aggression, and not for physical aggression. These findings suggest that similarity in aggression among befriended adolescents can be considered to be mainly a by-product rather than a leading dimension in friendship selection.     

Distributed attentional deficits in chronic methamphetamine abusers: evidence from the Attentional Network Task (ANT)

Objective

The goal of the present study was to examine distributed attentional functions in long-term but currently abstinent methamphetamine (MA) abusers using a task that measures attentional alertness, orienting, and conflict resolution.

Methods

Thirty currently abstinent MA abusers (1 month-5 years) and 22 healthy non-substance using adults were administered a multimodal version of the Attentional Network Task (ANT-I). In this task subjects identified the direction of a centrally presented arrow using a key press. Analyses examined the interaction between alerting tones, location cueing and congruency between the target arrows and flanking distractor stimuli.

Results

All participants were faster when an auditory tone preceded the trial onset (p < 0.001), on trials in which a valid cue preceded the location of the target arrow (p < 0.001), and on congruent trials (i.e., when all display arrows faced in the same direction) (p < 0.001). Of primary interest was the finding that MA abusers were more influenced by the conflict between the peripheral arrows and the central target arrow (p = 0.009). There were also correlations between length of drug sobriety and executive function as well as between drug-induced psychiatric symptoms and alertness.

Conclusions

These results suggest that chronic MA abusers display cognitive deficits that may reflect a specific vulnerability to distraction on a task of executive function. These findings are consistent with other studies that have reported deficits in anterior attentional systems and top-down cognitive control.     

Long‐Term Outcomes of Traumatic Brain Injury in Early Childhood

Mild traumatic brain injury (mTBI) is a leading cause of injury among children, with approximately 15% of children experiencing a TBI prior to 15 years of age. Acutely, mTBI has been associated with a range of cognitive, physical, emotional and behavioural impairments. However, few studies have examined outcomes beyond five years post injury, long before the developmental process is complete and the full extent of any deficits may manifest. Our group had the unique opportunity to use data from a longitudinal birth cohort of 1265 children (Christchurch Health and Development Study) to examine the long term outcomes of early injury (0–5 years). Information about these children, including mTBI events, had been collected at birth, 4 months and at yearly intervals until age 16, and again at ages 18, 21 and 25 years. We found that even after statistical control for a wide range of child and family confounds, children who had been hospitalized for an mTBI had increased inattention/hyperactivity and conduct as rated by mothers and teachers over ages 7–13 years. Increased rates of psychiatric disorders were over 14–16 years for those injured in the preschool, including symptoms consistent with Attention Deficit/Hyperactivity Disorder (ADHD), Odds Ratio = 4.6, Conduct Disorder (CD), Odds Ratio = 5.6 and Substance Abuse (Odds Ratio = 9.1). Over ages 21–25 ongoing behaviour problems were assessed using self‐reported arrests, violent offenses and property offenses. Compared to non‐injured individuals, mTBI groups were more likely to be arrested, involved in property, and violent offences. We controlled for a wide range of factors and there was still clear evidence of ongoing problems for individuals who had experienced a mTBI compared to their non injured counterparts. These findings provide compelling evidence of long term psychosocial and psychiatric outcomes following mTBI.     

Electrophysiological spatiotemporal dynamics during implicit visual threat processing

Numerous studies have found evidence for corticolimbic theta band electroencephalographic (EEG) oscillations in the neural processing of visual stimuli perceived as threatening. However, varying temporal and topographical patterns have emerged, possibly due to varying arousal levels of the stimuli. In addition, recent studies suggest neural oscillations in delta, theta, alpha, and beta-band frequencies play a functional role in information processing in the brain. This study implemented a data-driven PCA based analysis investigating the spatiotemporal dynamics of electroencephalographic delta, theta, alpha, and beta-band frequencies during an implicit visual threat processing task. While controlling for the arousal dimension (the intensity of emotional activation), we found several spatial and temporal differences for threatening compared to nonthreatening visual images. We detected an early posterior increase in theta power followed by a later frontal increase in theta power, greatest for the threatening condition. There was also a consistent left lateralized beta desynchronization for the threatening condition. Our results provide support for a dynamic corticolimbic network, with theta and beta band activity indexing processes pivotal in visual threat processing.     

Cerebral perfusion and neuropsychological follow up in mild traumatic brain injury: Acute versus chronic disturbances?

In a subgroup of patients with mild traumatic brain injury (TBI) residual symptoms, interfering with outcome and return to work, are found. With neuropsychological assessment cognitive deficits can be demonstrated although the pathological underpinnings of these cognitive deficits are not fully understood. As the admission computed tomography (CT) often is normal, perfusion CT imaging may be a useful indicator of brain dysfunction in the acute phase after injury in these patients.In the present study, directly after admission perfusion CT imaging was performed in mild TBI patients with follow-up neuropsychological assessment in those with complaints and a normal non-contrast CT. Neuropsychological tests comprised the 15 Words test Immediate Recall, Trailmaking test part B, Zoo Map test and the FEEST, which were dichotomized into normal and abnormal. Perfusion CT results of patients with normal neuropsychological test scores were compared to those with abnormal test scores.In total eighteen patients were included. Those with an abnormal score on the Zoo Map test had a significant lower CBV in the right frontal and the bilateral parieto-temporal white matter. Patients with an abnormal score on the FEEST had a significant higher MTT in the bilateral frontal white matter and a significant decreased CBF in the left parieto-temporal grey matter. No significant relation between the perfusion CT parameters and the 15 Words test and the Trailmaking test part B was present.In conclusion, impairments in executive functioning and emotion perception assessed with neuropsychological tests during follow up were related to differences in cerebral perfusion at admission in mild TBI. The pathophysiological concept of these findings is discussed.     

Mind,brain and body. Healing trauma: the way forward

The paper explores an interdisciplinary whole person approach to healing from trauma that conserves our rich inheritance from Jung but also takes on board insights from research in the areas of attachment, trauma and the neurobiology of emotion. It is now over 20 years since insights from neurobiology began to be used to inform clinical practice. The paper reviews key insights which have emerged, along with the ways they enable therapists to help mind, brain and body to heal and the ways in which they clarify why, in clinical practice, we do what we do. Traditionally the emphasis has been on words, interpretations, and meaning‐making. Currently there is greater appreciation of the affective, relational, embodied aspects of therapeutic work and the way in which these relate to traumatic early interactive experience that is held outside of human awareness. The ways in which knowledge of particular systems of connectivity inform understanding of the whole mind‐brain‐body relationship are examined. The way forward for clinical practice to become more focused in order to help clients to heal in mind and body is reviewed.     

道德直觉决策及其机制探析

道德直觉决策研究是从直觉思维角度探讨决策者在道德境遇下的决策。道德直觉决策是道德情境下的直觉反应, 其理论基础包括躯体标记假说、社会直觉模型、双加工理论、事件特征情感复合体系以及双系统理论; 道德直觉决策机制至少包括：无意识加工、情绪加工和直觉加工三个基本的心理加工过程, 与之对应的神经系统则至少存在三个可能的脑神经回路：无意识加工的道德脑区、情绪加工的道德脑区和直觉加工的道德脑区。研究主要从客观和主观两方面分析了道德直觉决策的一般性影响因素--文化、道德境遇、经验、情绪和道德直觉; 揭示了道德直觉决策的加工机制。未来研究应在加强理论建构的基础上, 通过更缜密细致的实验设计去探究决策过程中各因素的交互作用, 并明确道德脑区之间的联结。