Emotion revealed through body motion: gender impact

Body motion is a rich and reliable source of information for daily life social cognition, interaction and non-verbal communication. Yet gender effects in body language reading are largely unknown, and a few previous findings are sparse and controversial. Investigation of gender impact on body language reading is of substantial value for clarification of the nature of neurodevelopmental and psychiatric disorders (such as autism, attention deficit hyperactivity disorder, eating and anxiety disorders) characterized by aberrant social cognition. Many of these disorders are gender-specific: females and males are differently affected in terms of clinical picture, prevalence, and severity. The motivation of the present work was to clarify whether, and, if so, how gender affects body language reading in typically developing adults. We intended to make a step toward a framework for evaluation gender differences in the social brain in psychiatric and neurodevelopmental disorders. In our experiments, body motion was represented by a point-light technique as a set of dots on the joints of an otherwise invisible body. This helps to isolate information revealed by body motion from other visual cues (e.g., color, shape). In the first study (Sokolov et al., 2011), by using a three alternative-forced choice paradigm, participants had to indicate whether a display portrayed happy, neutral or angry knocking at a door. The findings show that gender affects accuracy rather than speed of body language reading. This effect, however, is modulated by emotional content of actions: males surpass in recognition accuracy of happy actions, whereas females tend to excel in recognition of hostile angry knocking movement. In the second study (Krüger et al., 2013), a similar pattern of results was found for subtle emotions expressed by point-light human locomotion: Males surpass females in recognition accuracy and readiness to respond to happy walking portrayed by female actors, whereas females tend to be better in recognition of angry locomotion expressed by male actors. In contrast to widespread beliefs about female superiority in social cognition, this work suggests that gender effects in body language reading are largely modulated by emotional content of actions. Further research should combine methods of social neuroscience to uncover neural circuits underlying gender differences in the social brain

A study on cerebral activity by means of combined EEG-fMRI in neuropsychological disorders in childhood

This study is composed by two parts, both focusing on post-calcarine ventral, occipito-temporal visual pathway (“ventral stream”), and on occipito- temporal cortex, structures involved in images and in face processing. In the first part of the study I have analyzed gamma-band ERSP (event-related spectral perturbations) and fMRI BOLD activations in response to recognizable and not recognizable visual stimuli, in typical children and in children affected by "ventral type" Cerebral Visual Impairment, trying to show how the deficits in "ventral" tasks could be investigated using both a neurophysiological and a neuroimaging approach. However I was not able to reproduce preliminary, promising data on gamma-band ERSP because of excessive electrical noise during EEG recordings, most likely because of an equipment radical and unexpected change. Despite these issues, taking advantage of the peculiar features and strength points of the new equipment (a dense-array EEG machine), I continued my work on visual perception and the occipito- temporal visual network using ERPs recordings (part 2), that are substantially less affected from the AC electrical noise usually present in every EEG recording. In particular, I recorded high density ERP responses to neutral and emotional visual face stimuli in typical children and in children affected by Autism Spectrum Disorder, a condition in which face-processing neural networks have been often found dysfunctional in neurophysiological and functional neuroimaging studies. However, evidence regarding face processing in Autism Spectrum Disorders is still contradictory and neurophysiological methods used are heterogeneous. Therefore I designed and applied an experimental paradigm trying to control most of the known or suspected confounding variables in this kind of studies. Using neutral and emotional faces, and trees as non-face stimuli, I was able to modulate both latency and amplitude of the main face-sensitive ERPs (N170, P1, peak-to-peak N170) as a function of stimulus and group conditions. These findings support the hypothesis of an early (first 200 msec) impairment in both neutral and emotional face processing in children affected by Autism Spectrum Disorders

Linking structural and effective brain connectivity: structurally informed Parametric Empirical Bayes (si-PEB).

Despite the potential for better understanding functional neuroanatomy, the complex relationship between neuroimaging measures of brain structure and function has confounded integrative, multimodal analyses of brain connectivity. This is particularly true for task-related effective connectivity, which describes the causal influences between neuronal populations. Here, we assess whether measures of structural connectivity may usefully inform estimates of effective connectivity in larger scale brain networks. To this end, we introduce an integrative approach, capitalising on two recent statistical advances: Parametric Empirical Bayes, which provides group-level estimates of effective connectivity, and Bayesian model reduction, which enables rapid comparison of competing models. Crucially, we show that structural priors derived from high angular resolution diffusion imaging on a dynamic causal model of a 12-region network-based on functional MRI data from the same subjects-substantially improve model evidence (posterior probability 1.00). This provides definitive evidence that structural and effective connectivity depend upon each other in mediating distributed, large-scale interactions in the brain. Furthermore, this work offers novel perspectives for understanding normal brain architecture and its disintegration in clinical conditions

Attention allocation during the observation of biological motion: an EEG study

The processing of observed biological motion that is the movement of biological organisms has an important role in animals’ vigilance and survival. For humans, it is also implicated in the development of social cognition and communication, with infants showing preferential attention towards motion from an early age. Further, adults can extract a broad range of social information from the biological motion of human figures represented by dots of light (point-light displays), that contain kinematic, structural and dynamic information. From this information, humans can identify individual actors, their sex, emotional state (angry, happy, and sad) and walking direction even when obfuscated by additional noise. The processing of biological motion draws on different cognitive systems such as working memory, selective attention and sensorimotor processing. Humans demonstrate an attentional bias towards human forms and biological motion, compared to other non-biological stimuli, and the observation of biological movement activates sensorimotor cortical regions. Previous research has used EEG to measure mu frequency (~ 8-13 Hz) changes and to infer the activation of sensorimotor regions during biological movement observation. This sensorimotor activation is thought to be an indication of online movement simulation. It has been demonstrated that top-down attentional processes modulate the engagement of sensorimotor simulation during movement observation. What remains unknown is whether biological motion exogenously captures spatial attention and, in turn, modulates sensorimotor simulation; the current study sought to explore this question. In the current study, I used an attentional bias paradigm where movement and control point-light displays are presented laterally and simultaneously as irrelevant cues. Relatively decreased reaction times to subsequent targets that appear in the same location as a cue reflects preferential processing of that preceding cue. I simultaneously recorded EEG and calculated mu frequency changes at both central and occipital electrode locations. I find decreased reaction times and an increase in correct responses to targets that replace the scrambled point light display (PLD), which represents non-biological motion, compared to targets that replaced the coherent PLD representing biological movement. In addition, EEG analysis revealed a left hemisphere bias, with post hoc analysis revealing this bias is driven by the central electrodes; with a larger desynchronisation in the left central electrode compared to the right central electrode, whereas, occipital alpha was desynchronised symmetrically. Together, the behavioural and EEG findings suggest an inhibition of return (IOR) effect

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Functional Connectivity of the Rodent Brain Using Optical Imaging

RÉSUMÉ L'objectif de cette thèse de doctorat est d’appliquer la connectivité fonctionnelle dans une variété de modèles animaux, à l’aide de plusieurs techniques d’imagerie optique. Le cerveau, même au repos, montre une activité métabolique élevée : la corrélation des fluctuations spontanées lentes permet d’identifier des régions cérébrales distantes mais connectées; d’où le terme connectivité fonctionnelle. Les changements dans l’activité spontanée peuvent donner un aperçu des processus neuronaux qui comprennent la majorité de l’activité métabolique du cerveau, et constituent en conséquent une vaste source de changements reliés aux maladies. L’hémodynamique du cerveau peut être modifiée grâce à des affections neurovasculaires et avoir un effet sur l’activité au repos. Cette thèse vise la compréhension des changements de connectivité fonctionnelle induits par des maladies, à l’aide de l’imagerie optique fonctionnelle. Les techniques d’imagerie explorées dans les deux premières contributions de cette thèse sont l’Imagerie Optique Intrinsèque et l’Imagerie par Granularité Laser. Ensemble, elles peuvent estimer les changements de consommation d'oxygène, étroitement liés à l’activité neuronale. Ces techniques possèdent des résolutions temporelles et spatiales adéquates et bien adaptées pour imager la convexité du cortex cérébral. Dans le dernier article, une modalité d’imagerie en profondeur, la Tomographie Photoacoustique a été utilisée chez le rat nouveau-né. La Tomographie par Cohérence Optique et la Tomographie Laminaire Optique font également partie de la gamme des techniques d’imagerie développées et appliquées dans d’autres collaborations. La première partie des résultats mesure les changements de connectivité fonctionnelle dans un modèle d’activité épileptiforme aiguë chez le rongeur. Il y a des augmentations ainsi que des diminutions entre les corrélations homologues, avec une faible dépendance aux crises épileptiques. Ces changements suggèrent un découplage potentiel entre les paramètres hémodynamiques dans les réseaux au repos, en soulignant l’importance d’investiguer les réseaux épileptiques à l’aide de plusieurs mesures hémodynamiques indépendantes. La deuxième partie des travaux étudie un nouveau modèle de rigidité artérielle chez la souris : la calcification unilatérale de la carotide droite. L’analyse de connectivité basé sur les régions d’intérêt montre une tendance décroissante de corrélation homologue dans les cortex moteur et cingulum. L’analyse de graphes montre une randomisation des réseaux corticaux, ce qui suggère une perte de connectivité; plus spécifiquement, dans le cortex moteur ipsilateral à la carotide----------ABSTRACT The aim of this thesis is to apply functional connectivity in a variety of animal models, using several optical imaging modalities. Even at rest, the brain shows high metabolic activity: the correlation in slow spontaneous fluctuations identifies remotely connected areas of the brain; hence the term “functional connectivity”. Ongoing changes in spontaneous activity may provide insight into the neural processing that takes most of the brain metabolic activity, and so may provide a vast source of disease related changes. Brain hemodynamics may be modified during disease and affect resting-state activity. The thesis aims to better understand these changes in functional connectivity due to disease, using functional optical imaging. The optical imaging techniques explored in the first two contributions of this thesis are Optical Imaging of Intrinsic Signals and Laser Speckle Contrast Imaging, together they can estimate the metabolic rate of oxygen consumption, that closely parallels neural activity. They both have adequate spatial and temporal resolution and are well adapted to image the convexity of the mouse cortex. In the last article, a depth-sensitive modality called photoacoustic tomography was used in the newborn rat. Optical coherence tomography and laminar optical tomography were also part of the array of imaging techniques developed and applied in other collaborations. The first article of this work shows the changes in functional connectivity in an acute murine model of epileptiform activity. Homologous correlations are both increased and decreased with a small dependence on seizure duration. These changes suggest a potential decoupling between the hemodynamic parameters in resting-state networks, underlining the importance to investigate epileptic networks with several independent hemodynamic measures. The second study examines a novel murine model of arterial stiffness: the unilateral calcification of the right carotid. Seed-based connectivity analysis showed a decreasing trend of homologous correlation in the motor and cingulate cortices. Graph analyses showed a randomization of the cortex functional networks, suggesting a loss of connectivity, more specifically in the motor cortex ipsilateral to the treated carotid; however these changes are not reflected in differentiated metabolic estimates. Confounds remain due to the fact that carotid rigidification gives rise to neural decline in the hippocampus as well as unilateral alteration of vascular pulsatility; howeve

Deep Brain Stimulation (DBS) Applications

The issue is dedicated to applications of Deep Brain Stimulation and, in this issue, we would like to highlight the new developments that are taking place in the field. These include the application of new technology to existing indications, as well as ‘new’ indications. We would also like to highlight the most recent clinical evidence from international multicentre trials. The issue will include articles relating to movement disorders, pain, psychiatric indications, as well as emerging indications that are not yet accompanied by clinical evidence. We look forward to your expert contribution to this exciting issue