Neural signatures of bullying experience and social rejection in teenagers.

Relational bullying in schools is one of the most frequent forms of violence and can have severe negative health impact, e.g. depression. Social exclusion is the most prominent form of relational bullying that can be operationalized experimentally. The present study used MR-based perfusion imaging (pCASL) to investigate the neural signatures of social exclusion and its relationship with individually different extent of previous bullying experience. Twenty-four teenagers reporting bullying experience at different extent were scanned during a virtual ball-tossing (Cyberball game). Our findings showed that social exclusion (relative to social inclusion) activated frontal brain areas: sub- and perigenual anterior cingulate cortex (sg/pgACC), left inferior frontal cortex (IFG), and dorsolateral prefrontal cortex. Positive relationship between exclusion-specific signal increase and individually different extents of prior bullying experience was for the first time observed in left IFG and sgACC. This suggests that more frequent prior experience has conditioned greater mentalizing and/or rumination, in order to cope with the situation. While this interpretation remains speculative, the present data show that the experience of being bullied partly sensitizes the neural substrate relevant for the processing of social exclusion.

Synaptic Characteristics of Amorphous Boron Nitride-Based Memristors on a Highly Doped Silicon Substrate for Neuromorphic Engineering.

In this study, the resistive switching and synaptic properties of a complementary metal-oxide semiconductor-compatible Ti/a-BN/Si device are investigated for neuromorphic systems. A gradual change in resistance is observed in a positive SET operation in which Ti diffusion is involved in the conducting path. This operation is extremely suitable for synaptic devices in hardware-based neuromorphic systems. The isosurface charge density plots and experimental results confirm that boron vacancies can help generate a conducting path, whereas the conducting path generated by a Ti cation from interdiffusion forms is limited. A negative SET operation causes a considerable decrease in the formation energy of only boron vacancies, thereby increasing the conductivity in the low-resistance state, which may be related to RESET failure and poor endurance. The pulse transient characteristics, potentiation and depression characteristics, and good retention property of eight multilevel cells also indicate that the positive SET operation is more suitable for a synaptic device owing to the gradual modulation of conductance. Moreover, pattern recognition accuracy is examined by considering the conductance values of the measured data in the Ti/a-BN/Si device as the synaptic part of a neural network. The linear and symmetric synaptic weight update in a positive SET operation with an incremental voltage pulse scheme ensures higher pattern recognition accuracy.

The grounding of abstract concepts in the motor and visual system: An fMRI study.

The grounding of concepts in the sensorimotor brain systems is controversially discussed. Grounded cognition models propose that concepts are represented in modality-specific sensorimotor, but also emotional and introspective brain areas depending on specific experiences during concept acquisition. Accumulating evidence suggests that concrete concepts are closely linked to modality-specific systems, whereas the mere existence of abstract concepts seems to contradict grounded cognition approaches. Here, using functional magnetic resonance imaging, we adopted a theory-driven approach frequently used for investigating concrete concepts to the domain of abstract concepts: We compared brain activation to abstract concepts with a known motor versus visual feature content as determined by a previous property listing study. Carefully matched motor (e.g., fitness) and visual (e.g., beauty) abstract words were presented to 24 participants along with pseudowords while performing a lexical decision task. Furthermore, participants performed two localizer tasks by actually moving their hands (motor localizer) and by looking at real pictures (visual localizer). Processing of motor abstract words specifically activated frontal and parietal motor areas, whereas processing of visual abstract words specifically elicited higher activity in temporo-occipital visual areas, albeit at a more lenient statistical threshold. According to inclusive masking analyses, this differential activity pattern to motor and visual abstract concepts overlapped with brain activations observed during hand movements (pre- and postcentral gyrus) and object perception (fusiform and lingual gyrus). Thus, consistent with the grounded cognition framework, our results suggest that, similar to concrete concepts, abstract concepts related to action and vision are grounded in modality-specific brain systems typically engaged in actual perception and action depending on their conceptual feature content.

Common Factors of Psychotherapy in Inpatients With Major Depressive Disorder: A Pilot Study.

Background: Psychotherapeutic interventions share common factors, which might contribute to treatment success independent of the type of psychotherapy. Previous research on common factors of psychotherapy was mostly conducted in outpatients and covered the development of common factors throughout a therapy over months or years. However, the role of common factors for the psychotherapeutic treatment success in inpatients during their hospital stay has not been addressed so far. The present research therefore aimed to explore changes of the common factors within a short-term stay at the psychiatric hospital for inpatients with major depressive disorder (MDD) and their relation to treatment outcome. Method: We developed a standardized manualized individual cognitive-behavioral psychotherapy (SMiCBT) for depression. The SMiCBT treatment lasted 4 weeks with eight therapy sessions. Following each treatment session, patients and therapists separately completed the questionnaire of "Stundenbogen für die Allgemeine und Differentielle Einzel-Psychotherapie" (STEP) to assess common factors from the perspective of the patient and the therapist. Severity of depression was also measured by the German version of the "Beck Depression Inventory" (BDI-II) before and after the treatment (SMiCBT). We conducted multilevel analysis for the longitudinal data for each scale of the STEP. Results: We found an improvement in the severity of depressive symptoms across the treatment period according to BDI-II scores. Regarding the STEP scales, motivational clarification and problem-solving scores increased over the treatment period for both patient and therapist perspectives. This was not the case for the scale therapeutic relationship. Furthermore, baseline levels of motivational clarification and problem solving were related to the treatment response. Limitations: The results have to be interpreted with care because of the small sample with MDD and the lack of a control group for comparison of treatment outcome. Conclusion: Our data demonstrate that common factors improve within a short-term psychotherapy in inpatients with MDD. Most importantly, our research highlights the distinguished role of motivational clarification and problem solving for the improvement of depressive symptoms during short-term psychotherapy in inpatient settings.

Brain Activation During Conceptual Processing of Action and Sound Verbs.

Grounded cognition approaches to conceptual representations postulate a close link between conceptual knowledge and the sensorimotor brain systems. The present fMRI study tested, whether a feature-specific representation of concepts, as previously demonstrated for nouns, can also be found for action- and sound-related verbs. Participants were presented with action- and soundrelated verbs along with pseudoverbs while performing a lexical decision task. Sound-related verbs activated auditory areas in the temporal cortex, whereas action-related verbs activated brain regions in the superior frontal gyrus and the cerebellum, albeit only at a more liberal threshold. This differential brain activation during conceptual verb processing partially overlapped with or was adjacent to brain regions activated during the functional localizers probing sound perception or action execution. Activity in brain areas involved in the processing of action information was parametrically modulated by ratings of action relevance. Comparisons of action- and sound-related verbs with pseudoverbs revealed activation for both verb categories in auditory and motor areas. In contrast to proposals of strong grounded cognition approaches, our study did not demonstrate a considerable overlap of activations for action- and sound-related verbs and for the corresponding functional localizer tasks. However, in line with weaker variants of grounded cognition theories, the differential activation pattern for action- and sound-related verbs was near corresponding sensorimotor brain regions depending on conceptual feature relevance. Possibly, action-sound coupling resulted in a mutual activation of the motor and the auditory system for both action- and sound-related verbs, thereby reducing the effect sizes for the differential contrasts.

When Action Observation Facilitates Visual Perception: Activation in Visuo-Motor Areas Contributes to Object Recognition.

Recent evidence suggests an interaction between the ventral visual-perceptual and dorsal visuo-motor brain systems during the course of object recognition. However, the precise function of the dorsal stream for perception remains to be determined. The present study specified the functional contribution of the visuo-motor system to visual object recognition using functional magnetic resonance imaging and event-related potential (ERP) during action priming. Primes were movies showing hands performing an action with an object with the object being erased, followed by a manipulable target object, which either afforded a similar or a dissimilar action (congruent vs. incongruent condition). Participants had to recognize the target object within a picture-word matching task. Priming-related reductions of brain activity were found in frontal and parietal visuo-motor areas as well as in ventral regions including inferior and anterior temporal areas. Effective connectivity analyses suggested functional influences of parietal areas on anterior temporal areas. ERPs revealed priming-related source activity in visuo-motor regions at about 120 ms and later activity in the ventral stream at about 380 ms. Hence, rapidly initiated visuo-motor processes within the dorsal stream functionally contribute to visual object recognition in interaction with ventral stream processes dedicated to visual analysis and semantic integration.

Neural activation in humans during a simple motor task differs between BDNF polymorphisms.

The BDNF Val66Met polymorphism has been linked to decreased synaptic plasticity involved in motor learning tasks. We investigated whether individual differences in this polymorphism may promote differences in neural activity during a two-alternative forced-choice motor performance. In two separate sessions, the BOLD signal from 22 right-handed healthy men was measured during button presses with the left and right index finger upon visual presentation of an arrow. 11 men were Val66Val carriers (ValVal group), the other 11 men carried either the Val66Met or the Met66Met polymorphism (Non-ValVal group). Reaction times, resting and active motor thresholds did not differ between ValVal and Non-ValVal groups. Compared to the ValVal group the Non-ValVal group showed significantly higher BOLD signals in the right SMA and motor cingulate cortex during motor performance. This difference was highly consistent for both hands and across all four sessions. Our finding suggests that this BDNF polymorphism may not only influence complex performance during motor learning but is already associated with activation differences during rather simple motor tasks. The higher BOLD signal observed in Non-ValVal subjects suggests the presence of cumulative effects of the polymorphism on the motor system, and may reflect compensatory functional activation mediating equal behavioral performance between groups.

Dissociating the representation of action- and sound-related concepts in middle temporal cortex.

Modality-specific models of conceptual memory propose close links between concepts and the sensory-motor systems. Neuroimaging studies found, in different subject groups, that action-related and sound-related concepts activated different parts of posterior middle temporal gyrus (pMTG), suggesting a modality-specific representation of conceptual features. However, as these different parts of pMTG are close to each other, it is possible that the observed anatomical difference is merely related to interindividual variability. In the present functional magnetic resonance imaging study, we now investigated within the same participant group a possible conceptual feature-specific organization in pMTG. Participants performed lexical decisions on sound-related (e.g., telephone) and action-related (hammer) words. Sound words elicited higher activity in anterior pMTG adjacent to auditory association cortex, but action-related words did so in posterior pMTG close to motion sensitive areas. These results confirm distinct conceptual representations of sound and action in pMTG, just adjacent to the respective modality-specific cortices.

Mechanisms underlying flexible adaptation of cognitive control: behavioral and neuroimaging evidence in a flanker task.

Cognitive control can be adapted flexibly according to the conflict level in a given situation. In the Eriksen flanker task, interference evoked by flankers is larger in conditions with a higher, rather than a lower proportion of compatible trials. Such compatibility ratio effects also occur for stimuli presented at two spatial locations suggesting that different cognitive control settings can be simultaneously maintained. However, the conditions and the neural correlates of this flexible adaptation of cognitive control are only poorly understood. In the present study, we further elucidated the mechanisms underlying the simultaneous maintenance of two cognitive control settings. In behavioral experiments, stimuli were presented centrally above and below fixation and hence processed by both hemispheres or lateralized to stimulate hemispheres differentially. The different compatibility ratio at two stimulus locations had a differential influence on the flanker effect in both experiments. In an fMRI experiment, blocks with an identical compatibility ratio at two central spatial locations elicited stronger activity in a network of prefrontal and parietal brain areas, which are known to be involved in conflict resolution and cognitive control, as compared with blocks with a different compatibility ratio at the same spatial locations. This demonstrates that the simultaneous maintenance of two conflicting control settings vs. one single setting does not recruit additional neural circuits suggesting the involvement of one single cognitive control system. Instead a crosstalk between multiple control settings renders adaptation of cognitive control more efficient when only one uniform rather than two different control settings has to be simultaneously maintained.

Neuroplasticity of semantic representations for musical instruments in professional musicians.

Professional musicians constitute a model par excellence for understanding experience-dependent plasticity in the human brain, particularly in the auditory domain. Their intensive sensorimotor experience with musical instruments has been shown to entail plastic brain alterations in cortical perceptual and motor maps. It remains an important question whether this neuroplasticity might extend beyond basic perceptual and motor functions and even shape higher-level conceptualizations by which we conceive our physical and social world. Here we show using functional magnetic resonance imaging (fMRI) that conceptual processing of visually presented musical instruments activates auditory association cortex encompassing right posterior superior temporal gyrus, as well as adjacent areas in the superior temporal sulcus and the upper part of middle temporal gyrus (pSTG/MTG) only in musicians, but not in musical laypersons. These areas in and adjacent to auditory association cortex were not only recruited by conceptual processing of musical instruments during visual object recognition, but also by auditory perception of real sounds. Hence, the unique intensive experience of musicians with musical instruments establishes a link between auditory perceptual and conceptual brain systems. Experience-driven neuroplasticity in musicians is thus not confined to alterations of perceptual and motor maps, but even leads to the establishment of higher-level semantic representations for musical instruments in and adjacent to auditory association cortex. These findings highlight the eminent importance of sensory and motor experience for acquiring rich concepts.

Tracking the time course of action priming on object recognition: evidence for fast and slow influences of action on perception.

Perception and action are classically thought to be supported by functionally and neuroanatomically distinct mechanisms. However, recent behavioral studies using an action priming paradigm challenged this view and showed that action representations can facilitate object recognition. This study determined whether action representations influence object recognition during early visual processing stages, that is, within the first 150 msec. To this end, the time course of brain activation underlying such action priming effects was examined by recording ERPs. Subjects were sequentially presented with two manipulable objects (e.g., tools), which had to be named. In the congruent condition, both objects afforded similar actions, whereas dissimilar actions were afforded in the incongruent condition. In order to test the influence of the prime modality on action priming, the first object (prime) was presented either as picture or as word. We found an ERP effect of action priming over the central scalp as early as 100 msec after target onset for pictorial, but not for verbal primes. A later action priming effect on the N400 ERP component known to index semantic integration processes was obtained for both picture and word primes. The early effect was generated in a fronto-parietal motor network, whereas the late effect reflected activity in anterior temporal areas. The present results indicate that action priming influences object recognition through both fast and slow pathways: Action priming affects rapid visuomotor processes only when elicited by pictorial prime stimuli. However, it also modulates comparably slow conceptual integration processes independent of the prime modality.

The neural substrate of positive bias in spontaneous emotional processing.

Even in the presence of negative information, healthy human beings display an optimistic tendency when thinking of past success and future chances, giving a positive bias to everyday's cognition. The tendency to actively select positive thoughts suggests the existence of a mechanism to exclude negative content, raising the issue of its dependence on mechanisms like those of effortful control. Using perfusion imaging, we examined how brain activations differed according to whether participants were left to prefer positive thoughts spontaneously, or followed an explicit instruction to the same effect, finding a widespread dissociation of brain perfusion patterns. Under spontaneous processing of emotional material, recruitment of areas associated with effortful attention, such as the dorsolateral prefrontal cortex, was reduced relative to instructed avoidance of negative material (F(1,58) = 26.24, p = 0.047, corrected). Under spontaneous avoidance perfusion increments were observed in several areas that were deactivated by the task, including the perigenual medial prefrontal cortex. Furthermore, individual differences in executive capacity were not associated with positive bias. These findings suggest that spontaneous positive cognitive emotion regulation in health may result from processes that, while actively suppressing emotionally salient information, differ from those associated with effortful and directed control.

Components of acquisition-to-acquisition variance in continuous arterial spin labelling (CASL) imaging.

BACKGROUND: Images of perfusion estimates obtained with the continuous arterial spin labelling technique are characterized by variation between single acquisitions. Little is known about the spatial determinants of this variation during the acquisition process and their impact on voxel-by-voxel estimates of effects. RESULTS: We show here that the spatial patterns of covariance between voxels arising during the acquisition of these images uncover distinct mechanisms through which this variance arises: through variation in global perfusion levels; through the action of large vessels and other, less well characterized, large anatomical structures; and through the effect of noisy areas such as the edges of the brain. CONCLUSIONS: Knowledge of these covariance patterns is important to experimenters for a correct interpretation of findings, especially for studies where relatively few acquisitions are made.

Baseline brain perfusion and the serotonin transporter promoter polymorphism.

BACKGROUND: The serotonin transporter length repeat polymorphism (5-HTTLPR) in the promoter region of the serotonin transporter gene (SLC6A4) has been associated in healthy subjects with changes in basal perfusion levels in the limbic system and ventral prefrontal areas, regions involved in the pathophysiology of depression and anxiety, suggesting the existence of a neurobiological trait predisposing to these disorders. We reassess the findings of an increased baseline perfusion in the amygdala and ventral prefrontal areas in healthy carriers of the risk genotype in a much larger sample than in previous studies. METHODS: A cohort of 183 healthy European individuals underwent perfusion imaging with continuous arterial spin-labeling (CASL) while resting quietly in the scanner for 8 minutes. Participants were genotyped to assess the occurrence of the short allele and the Lg and La variants of the long repeat. RESULTS: No association between the 5-HTTLPR polymorphism and baseline brain perfusion was detected in the regions of interest or elsewhere in the brain. In the amygdala, variability in baseline perfusion was explained in large part by global cerebral flow levels (between 50% and 55%), in minor part by sex (between 4% and 5%), but not by genotype (less than .5%). Power analyses showed that the study was of sufficient size to be informative. CONCLUSIONS: The findings did not confirm the existence of a biological marker of the effect of 5-HTTLPR polymorphism in the amygdala or in the orbitofrontal cortex.

Components of variance in brain perfusion and the design of studies of individual differences: the baseline study.

Simple baseline studies correlate average perfusion levels measured at rest with individual variables, or contrast subject groups as in case-control studies. In this methodological work, we summarize some formal properties of the design of these studies, and investigate the sources of variance that characterize data acquired with the arterial spin labeling technique, with the purpose of alerting users to the main sources of variation that determine background variance and affect the power of statistical tests. This design typology is characterized by two variance components: between acquisitions and between subjects. We show that variation between acquisitions is affected by the presence of large vessels and venous sinuses, with potential adverse effects especially in the temporal and insular regions, and provide maps of the number of acquisitions or subjects required to reach the desired estimate precision. Furthermore, we show that the largest source of variation between subjects is captured by global perfusion levels, and can in principle be removed by adjusting the data. Significance levels, however, are not always only improved by the adjustment procedure; we provide an example in the correlation with age, and attempt to explain the consequences of the adjustment with the help of a principal component analysis of the data. We also show the existence of variation between subjects in the perfusion in the territory of the posterior cerebral artery and in hemispheric asymmetry.

The sound of concepts: four markers for a link between auditory and conceptual brain systems.

Traditionally, concepts are conceived as abstract mental entities distinct from perceptual or motor brain systems. However, recent results let assume modality-specific representations of concepts. The ultimate test for grounding concepts in perception requires the fulfillment of the following four markers: conceptual processing during (1) an implicit task should activate (2) a perceptual region (3) rapidly and (4) selectively. Here, we show using functional magnetic resonance imaging and recordings of event-related potentials, that acoustic conceptual features recruit auditory brain areas even when implicitly presented through visual words. Fulfilling the four markers, the findings of our study unequivocally link the auditory and conceptual brain systems: recognition of words denoting objects, for which acoustic features are highly relevant (e.g.,"telephone"), ignited cell assemblies in posterior superior and middle temporal gyri (pSTG/MTG) within 150 ms that were also activated by sound perception. Importantly, activity within a cluster of pSTG/MTG increased selectively as a function of acoustic, but not of visual and action-related feature relevance. The implicitness of the conceptual task, the selective modulation of left pSTG/MTG activity by acoustic feature relevance, the early onset of this activity at 150 ms and its anatomical overlap with perceptual sound processing are four markers for a modality-specific representation of auditory conceptual features in left pSTG/MTG. Our results therefore provide the first direct evidence for a link between perceptual and conceptual acoustic processing. They demonstrate that access to concepts involves a partial reinstatement of brain activity during the perception of objects.

Baseline brain perfusion and working memory capacity: a neuroimaging study.

Early studies of rest cerebral metabolism and perfusion reported no association with intellectual capacity. We revisit this issue using a larger sample (N=146) and a continuous arterial spin labeling technique to measure perfusion, and working memory capacity as a measure of intellectual capacity. In the cortex, working memory capacity correlated diffusely and negatively with perfusion. This negative association was more marked in the prefrontal and temporal cortex of the left hemisphere. However, there were also weak positive correlations in the auditory areas, accompanied by analogous correlations in all other areas associated with sensory modalities, with a preference for right lateralization. These findings are discussed in terms of the cortical and vascular organization of the brain.

Conceptual flexibility in the human brain: dynamic recruitment of semantic maps from visual, motor, and motion-related areas.

Traditionally, concepts are assumed to be situational invariant mental knowledge entities (conceptual stability), which are represented in a unitary brain system distinct from sensory and motor areas (amodality). However, accumulating evidence suggests that concepts are embodied in perception and action in that their conceptual features are stored within modality-specific semantic maps in the sensory and motor cortex. Nonetheless, the first traditional assumption of conceptual stability largely remains unquestioned. Here, we tested the notion of flexible concepts using functional magnetic resonance imaging and event-related potentials (ERPs) during the verification of two attribute types (visual, action-related) for words denoting artifactual and natural objects. Functional imaging predominantly revealed crossover interactions between category and attribute type in visual, motor, and motion-related brain areas, indicating that access to conceptual knowledge is strongly modulated by attribute type: Activity in these areas was highest when nondominant conceptual attributes had to be verified. ERPs indicated that these category-attribute interactions emerged as early as 116 msec after stimulus onset, suggesting that they reflect rapid access to conceptual features rather than postconceptual processing. Our results suggest that concepts are situational-dependent mental entities. They are composed of semantic features which are flexibly recruited from distributed, yet localized, semantic maps in modality-specific brain regions depending on contextual constraints.

Experience-dependent plasticity of conceptual representations in human sensory-motor areas.

Concepts are composed of features related to different sensory and motor modalities such as vision, sound, and action. It is a matter of controversy whether conceptual features are represented in sensory-motor areas reflecting the specific learning experience during acquisition. In order to address this issue, we assessed the plasticity of conceptual representations by training human participants with novel objects under different training conditions. These objects were assigned to categories such that for one class of categories, the overall shape was diagnostic for category membership, whereas for the other class, a detail feature affording a particular action was diagnostic. During training, participants were asked to either make an action pantomime toward the detail feature of the novel object or point to it. In a categorization task at test, we assessed the neural correlates of the acquired conceptual representations by measuring electrical brain activity. Here, we show that the same object is differentially processed depending on the sensory-motor interactions during knowledge acquisition. Only in the pantomime group did we find early activation in frontal motor regions and later activation in occipito-parietal visual-motor regions. In the pointing training group, these effects were absent. These results show that action information contributes to conceptual processing depending on the specific learning experience. In line with modality-specific theories of conceptual memory, our study suggests that conceptual representations are established by the learning-based formation of cell assemblies in sensory-motor areas.