Parallel modeling of the electric field distribution in the brain

The term "Brain Imaging" identi�es a set of techniques to analyze the structure and/or functional behavior of the brain in normal and/or pathological situations. These techniques are largely used in the study of brain activity. In addition to clinical usage, analysis of brain activity is gaining popularity in others recent �fields, i.e. Brain Computer Interfaces (BCI) and the study of cognitive processes. In this context, usage of classical solutions (e.g. f MRI, PET-CT) could be unfeasible, due to their low temporal resolution, high cost and limited portability. For these reasons alternative low cost techniques are object of research, typically based on simple recording hardware and on intensive data elaboration process. Typical examples are ElectroEncephaloGraphy (EEG) and Electrical Impedance Tomography (EIT), where electric potential at the patient's scalp is recorded by high impedance electrodes. In EEG potentials are directly generated from neuronal activity, while in EIT by the injection of small currents at the scalp. To retrieve meaningful insights on brain activity from measurements, EIT and EEG relies on detailed knowledge of the underlying electrical properties of the body. This is obtained from numerical models of the electric �field distribution therein. The inhomogeneous and anisotropic electric properties of human tissues make accurate modeling and simulation very challenging, leading to a tradeo�ff between physical accuracy and technical feasibility, which currently severely limits the capabilities of these techniques. Moreover elaboration of data recorded requires usage of regularization techniques computationally intensive, which influences the application with heavy temporal constraints (such as BCI). This work focuses on the parallel implementation of a work-flow for EEG and EIT data processing. The resulting software is accelerated using multi-core GPUs, in order to provide solution in reasonable times and address requirements of real-time BCI systems, without over-simplifying the complexity and accuracy of the head models.

The Role of Multiple Social Categorisation in Promoting the Inclusion in the Human Group of Outgroup Members

Lo spazio senso-motorio come rappresentazione dei comportamenti intersoggettivi. Una nuova ipotesi sperimentale dalla filosofia alle neuroscienze

La ricerca ha preso le mosse da tre ipotesi fondamentali: 1) Esiste un legame tra processi cognitivi di basso ed alto livello; 2) Lo spazio senso-motorio è una percezione soggettiva; 3) Lo spazio senso-motorio varia in funzione delle diverse modalità di interazione sociale. La tesi sostiene che lo spazio senso-motorio si lascia modulare dalla semplice co-presenza di un altro agente umano e da interazioni cooperative e non cooperative. I capitoli I, II, III, hanno lo scopo di scomporre e spiegare il significato della prima, seconda e terza ipotesi; giungendo a formulare la tesi centrale che sarà poi dimostrata sperimentalmente nel capitolo IV. Il capitolo V introduce future linee di ricerca nell’ambito dell’etica proponendo una nuova ipotesi sul legame che potrebbe sussistere tra la percezione dello spazio durante l’interazione sociale e i giudizi morali. Il lavoro svolto chiama ad operare insieme diverse discipline che concorrono a formare le scienze cognitive: la storia della filosofia, la filosofia della mente contemporanea, la neuropsicologia sperimentale ed alcuni temi della psicologia sociale.

I fumetti e la glottodidattica: Proposte di insegnamento per l'italiano ls.

This study explores comics as an educational tool in teaching Italian as a foreign language, and shows that, in this perspective, the potential of this medium goes beyond the idea that pictures can help to understand words. Comics has to be understood as a unified text, where it is precisely the combination of pictures and words that promotes the development of the students' linguistic and communicative competences. The general educational potential of comics is analyzed in Chapter 1, with a focus on the notions of closure, cartooning and here and now, which are in harmony with the application of ludic teaching theories; an analysis then follows on the features of comics that can be exploited in the field of language teaching; finally a description is provided of the linguistic competences whose development can be favored by comics. Emphasis was placed only on those competences that are most affected by the context of use, i.e, lexical, textual, pragmatic and (inter-)cultural competences. In Chapter 2, three Italian comic books are analyzed with an eye to their use as teaching material in three ideally homogeneous classes, respectively belonging to the Common European Framework of Reference for Language A2, B2 and C2 levels. The cognitive processes carried out by students to achieve a global understanding of each book are postulated both for picture-to-picure and picture-to-word relations. After an overview of the main planning phases of a language-learning pathway, the educational approach adopted in Chapter 3 places the students at the core of the learning process, and emphasizes the need for a cooperative and interactional relationship between learners and teachers. In Chapter 4, three hypothetical learning pathways are described. Their main goal is to develop the linguistic and communicative competences of the students, who would then be able to understand and produce text not merely as learners, but rather as readers, hence users of an Italian cultural product.

Semantic memory involvement in the default mode network: a functional neuroimaging study using independent component analysis

The Default Mode Network (DMN) is a higher order functional neural network that displays activation during passive rest and deactivation during many types of cognitive tasks. Accordingly, the DMN is viewed to represent the neural correlate of internally-generated self-referential cognition. This hypothesis implies that the DMN requires the involvement of cognitive processes, like declarative memory. The present study thus examines the spatial and functional convergence of the DMN and the semantic memory system. Using an active block-design functional Magnetic Resonance Imaging (fMRI) paradigm and Independent Component Analysis (ICA), we trace the DMN and fMRI signal changes evoked by semantic, phonological and perceptual decision tasks upon visually-presented words. Our findings show less deactivation during semantic compared to the two non-semantic tasks for the entire DMN unit and within left-hemispheric DMN regions, i.e., the dorsal medial prefrontal cortex, the anterior cingulate cortex, the retrosplenial cortex, the angular gyrus, the middle temporal gyrus and the anterior temporal region, as well as the right cerebellum. These results demonstrate that well-known semantic regions are spatially and functionally involved in the DMN. The present study further supports the hypothesis of the DMN as an internal mentation system that involves declarative memory functions.

Capuchin Monkeys Exercise Self-control by Choosing Token Exchange Over an Immediate Reward

Self-control is a prerequisite for complex cognitive processes such as cooperation and planning. As such, comparative studies of self-control may help elucidate the evolutionary origin of these capacities. A variety of methods have been developed to test for self-control in non-human primates that include some variation of foregoing an immediate reward in order to gain a more favorable reward. We used a token exchange paradigm to test for self-control in capuchin monkeys (Cebus apella). Animals were trained that particular tokens could be exchanged for food items worth different values. To test for self-control, a monkey was provided with a token that was associated with a lower-value food. When the monkey exchanged the token, the experimenter provided the monkey with a choice between the lower-value food item associated with the token or another token that was associated with a higher-value food. If the monkey chose the token, they could then exchange it for the higher-value food. Of seven monkeys trained to exchange tokens, five demonstrated that they attributed value to the tokens by differentially selecting tokens for higher-value foods over tokens for lower-value foods. When provided with a choice between a food item or a token for a higher-value food, two monkeys selected the token significantly more than expected by chance. The ability of capuchin monkeys to forego an immediate food reward and select a token that could then be traded for a more preferred food demonstrated some degree of self-control. Thus, results suggest a token exchange paradigm could be a successful technique for assessing self-control in this New World species.

Using transcranial magnetic stimulation to probe decision-making and memory

Decision-making and memory are fundamental processes for successful human behaviour. For eye movements, the frontal eye fields (FEF), the supplementary eye fields (SEF), the dorsolateral prefrontal cortex (DLPFC), the ventrolateral frontal cortex and the anterior cingulum are important for these cognitive processes. The online approach of transcranial magnetic stimulation (TMS), i.e., the application of magnetic pulses during planning and performance of saccades, allows interfering specifically with information processing of the stimulated region at a very specific time interval (chronometry of cortical processing). The paper presents studies, which showed the different roles of the FEF and DLPFC in antisaccade control. The critical time interval of DLPFC control seems to be before target onset since TMS significantly increased the percentage of antisaccade errors at that time interval. The FEF seems to be important for the triggering of correct antisaccades. Bilateral stimulation of the DLPFC could demonstrate parallel information-processing transfer in spatial working memory during memory-guided saccades.

Shifted Coupling of EEG Driving Frequencies and fMRI Resting State Networks in Schizophrenia Spectrum Disorders

INTRODUCTION: The cerebral resting state in schizophrenia is altered, as has been demonstrated separately by electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) resting state networks (RSNs). Previous simultaneous EEG/fMRI findings in healthy controls suggest that a consistent spatiotemporal coupling between neural oscillations (EEG frequency correlates) and RSN activity is necessary to organize cognitive processes optimally. We hypothesized that this coupling is disorganized in schizophrenia and related psychotic disorders, in particular regarding higher cognitive RSNs such as the default-mode (DMN) and left-working-memory network (LWMN). METHODS: Resting state was investigated in eleven patients with a schizophrenia spectrum disorder (n = 11) and matched healthy controls (n = 11) using simultaneous EEG/fMRI. The temporal association of each RSN to topographic spectral changes in the EEG was assessed by creating Covariance Maps. Group differences within, and group similarities across frequencies were estimated for the Covariance Maps. RESULTS: The coupling of EEG frequency bands to the DMN and the LWMN respectively, displayed significant similarities that were shifted towards lower EEG frequencies in patients compared to healthy controls. CONCLUSIONS: By combining EEG and fMRI, each measuring different properties of the same pathophysiology, an aberrant relationship between EEG frequencies and altered RSNs was observed in patients. RSNs of patients were related to lower EEG frequencies, indicating functional alterations of the spatiotemporal coupling. SIGNIFICANCE: The finding of a deviant and shifted coupling between RSNs and related EEG frequencies in patients with a schizophrenia spectrum disorder is significant, as it might indicate how failures in the processing of internal and external stimuli, as commonly seen during this symptomatology (i.e. thought disorders, hallucinations), arise.

A tutorial on data-driven methods for statistically assessing ERP topographies

Dynamic changes in ERP topographies can be conveniently analyzed by means of microstates, the so-called "atoms of thoughts", that represent brief periods of quasi-stable synchronized network activation. Comparing temporal microstate features such as on- and offset or duration between groups and conditions therefore allows a precise assessment of the timing of cognitive processes. So far, this has been achieved by assigning the individual time-varying ERP maps to spatially defined microstate templates obtained from clustering the grand mean data into predetermined numbers of topographies (microstate prototypes). Features obtained from these individual assignments were then statistically compared. This has the problem that the individual noise dilutes the match between individual topographies and templates leading to lower statistical power. We therefore propose a randomization-based procedure that works without assigning grand-mean microstate prototypes to individual data. In addition, we propose a new criterion to select the optimal number of microstate prototypes based on cross-validation across subjects. After a formal introduction, the method is applied to a sample data set of an N400 experiment and to simulated data with varying signal-to-noise ratios, and the results are compared to existing methods. In a first comparison with previously employed statistical procedures, the new method showed an increased robustness to noise, and a higher sensitivity for more subtle effects of microstate timing. We conclude that the proposed method is well-suited for the assessment of timing differences in cognitive processes. The increased statistical power allows identifying more subtle effects, which is particularly important in small and scarce patient populations.

Self-disclosure and privacy calculus on social networking sites: the role of culture

Social Networking Sites (SNSs) have become extremely popular around the world. They rely on user-generated content to offer engaging experience to its members. Cultural differences may influence the motivation of users to create and share content on SNS. This study adopts the privacy calculus perspective to examine the role of culture in individual self-disclosure decisions. The authors use structural equation modeling and multi-group analysis to investigate this dynamics. The findings reveal the importance of cultural dimensions of individualism and uncertainty avoidance in the cognitive processes of SNS users.

Stress and hemostasis: an update

Numerous naturalistic, experimental, and mechanistic studies strongly support the notion that-as part of fight-or-flight response-hemostatic responses to acute psychosocial stress result in net hypercoagulability, which would protect a healthy organism from bleeding in case of injury. Sociodemographic factors, mental states, and comorbidities are important modulators of the acute prothrombotic stress response. In patients with atherosclerosis, exaggerated and prolonged stress-hypercoagulability might accelerate coronary thrombus growth following plaque rupture. Against a background risk from acquired prothrombotic conditions and inherited thrombophilia, acute stress also might trigger venous thromboembolic events. Chronic stressors such as job strain, dementia caregiving, and posttraumatic stress disorder as well as psychological distress from depressive and anxiety symptoms elicit a chronic low-grade hypercoagulable state that is no longer viewed as physiological but might impair vascular health. Through activation of the sympathetic nervous system, higher order cognitive processes and corticolimbic brain areas shape the acute prothrombotic stress response. Hypothalamic-pituitary-adrenal axis and autonomic dysfunction, including vagal withdrawal, are important regulators of hemostatic activity with longer lasting stress. Randomized placebo-controlled trials suggest that several cardiovascular drugs attenuate the acute prothrombotic stress response. Behavioral interventions and psychotropic medications might mitigate chronic low-grade hypercoagulability in stressed individuals, but further studies are clearly needed. Restoring normal hemostatic function with biobehavioral interventions bears the potential to ultimately decrease the risk of thrombotic diseases.

Static and dynamic characteristics of cerebral blood flow during the resting state in schizophrenia

Background: The cerebral network that is active during rest and is deactivated during goal-oriented activity is called the default mode network (DMN). It appears to be involved in self-referential mental activity. Atypical functional connectivity in the DMN has been observed in schizophrenia. One hypothesis suggests that pathologically increased DMN connectivity in schizophrenia is linked with a main symptom of psychosis, namely, misattribution of thoughts. Methods: A resting-state pseudocontinuous arterial spin labeling (ASL) study was conducted to measure absolute cerebral blood flow (CBF) in 34 schizophrenia patients and 27 healthy controls. Using independent component analysis (ICA), the DMN was extracted from ASL data. Mean CBF and DMN connectivity were compared between groups using a 2-sample t test. Results: Schizophrenia patients showed decreased mean CBF in the frontal and temporal regions (P < .001). ICA demonstrated significantly increased DMN connectivity in the precuneus (x/y/z = -16/-64/38) in patients than in controls (P < .001). CBF was not elevated in the respective regions. DMN connectivity in the precuneus was significantly correlated with the Positive and Negative Syndrome Scale scores (P < .01). Conclusions: In schizophrenia patients, the posterior hub-which is considered the strongest part of the DMN-showed increased DMN connectivity. We hypothesize that this increase hinders the deactivation of the DMN and, thus, the translation of cognitive processes from an internal to an external focus. This might explain symptoms related to defective self-monitoring, such as auditory verbal hallucinations or ego disturbances.

Mood and Memory: Mood congruity effects in absence of mood

Themood-congruity effect refers to facilitated processing of information when the affective valence of this information is congruent with the subject’s mood. In this paper we argue that mood may be a sufficient but not a necessary condition to produce the mood-congruity effect of selective learning. Two experiments are presented in which subjects learned lists of words with neutral, positive, and negative affective valences. In the learning task the subjects were instructed to behave as if they were depressed or happy. The mood-congruity effect was indeed obtained. The effect was stronger with subjects who “predicted” the relationship between mood and affective word valence than with subjects who were unaware of this relationship. The results are not simply attributed to task demands, but are interpreted in terms of a model of cognitive processes and people’s knowledge about mood states.

Balancing the mind: vestibular induced facilitation of egocentric mental transformations

The body schema is a key component in accomplishing egocentric mental transformations, which rely on bodily reference frames. These reference frames are based on a plurality of different cognitive and sensory cues among which the vestibular system plays a prominent role. We investigated whether a bottom-up influence of vestibular stimulation modulates the ability to perform egocentric mental transformations. Participants were significantly faster to make correct spatial judgments during vestibular stimulation as compared to sham stimulation. Interestingly, no such effects were found for mental transformation of hand stimuli or during mental transformations of letters, thus showing a selective influence of vestibular stimulation on the rotation of whole-body reference frames. Furthermore, we found an interaction with the angle of rotation and vestibular stimulation demonstrating an increase in facilitation during mental body rotations in a direction congruent with rightward vestibular afferents. We propose that facilitation reflects a convergence in shared brain areas that process bottom-up vestibular signals and top-down imagined whole-body rotations, including the precuneus and tempero-parietal junction. Ultimately, our results show that vestibular information can influence higher-order cognitive processes, such as the body schema and mental imagery.