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

Seeing emotions in others: Improving cognitive and neuronal mechanisms of facial expression processing

In the conceptual framework of affective neuroscience, this thesis intends to advance the understanding of the plasticity mechanisms of other’s emotional facial expression representations. Chapter 1 outlines a description of the neurophysiological bases of Hebbian plasticity, reviews influential studies that adopted paired associative stimulation procedures, and introduces new lines of research where the impact of cortico-cortical paired associative stimulation protocols on higher order cognitive functions is investigated. The experiments in Chapter 2 aimed to test the modulatory influence of a perceptual-motor training, based on the execution of emotional expressions, on the subsequent emotion intensity judgements of others’ high (i.e., full visible) and low-intensity (i.e., masked) emotional expressions. As a result of the training-induced learning, participants showed a significant congruence effect, as indicated by relatively higher expression intensity ratings for the same emotion as the one that was previously trained. Interestingly, although judged as overall less emotionally intense, surgical facemasks did not prevent the emotion-specific effects of the training to occur, suggesting that covering the lower part of other’s face do not interact with the training-induced congruence effect. In Chapter 3 it was implemented a transcranial magnetic stimulation study targeting neural pathways involving re-entrant input from higher order brain regions into lower levels of the visual processing hierarchy. We focused on cortical visual networks within the temporo-occipital stream underpinning the processing of emotional faces and susceptible to plastic adaptations. Importantly, we tested the plasticity-induced effects in a state dependent manner, by administering ccPAS while presenting different facial expressions yet afferent to a specific emotion. Results indicated that the discrimination accuracy of emotion-specific expressions is enhanced following the ccPAS treatment, suggesting that a multi-coil TMS intervention might represent a suitable tool to drive brain remodeling at a neural network level, and consequently influence a specific behavior

Exploring intermediate phenotypes with EEG: Working memory dysfunction in schizophrenia

This review brings together two strands of investigation in the neuropsychology and neurophysiology of schizophrenia that have been particularly productive over the last 20 years. We review the literature on working memory deficits, particularly in the visual domain, and changes in oscillatory neural activity as measured with electroencephalography (EEG) and magnetoencephalography (MEG). We argue that recent results suggest a link between these two phenomena, in that altered oscillations underlie some of the working memory deficits. We furthermore argue that early sensory mechanisms contribute more to working memory (and other) deficits than previously thought. The final part of our review suggests links between working memory, oscillations, and their alterations in schizophrenia and the dopamine, GABA, glutamate and acetylcholine system. These links have already resulted in the development of new remediation strategies, which have some translational potential

Emoční paradox schizofrenního okruhu

THE EMOTION-PARADOX 1 Abstrakt Emoční paradox u schizofrenie popisuje disociaci mezi hrubě narušeným vnímáním emocí a jejich zachovaným prožíváním. Většina zastává, že emoční paradox vzniká z generalizovaného poškození emočního vjemu. Ostatní oponují, že představuje pouhý artefakt metodických omezení, popřípadě odlišnou disociaci mezi explicitním a implicitním zpracováním emocí. Předmětem této práce bylo objasnit původ emočního paradoxu u schizofrenie. Za tímto účelem byly provedeny dvě studie. Obé vycházely ze shodného vzorku, který zahrnoval 45 osob se schizofrenií o různorodé symptomatologii a 45 osob bez vlastní či rodinné psychiatrické anamnézy. Skupiny si odpovídaly věkem, pohlavím, vzděláním a hudebním vzděláním. Ve Studii 1 si probandi poslechli řadu hudebních podnětů a zhodnotili svůj vjem a prožitek jejich libosti a budivosti. Ve Studii 2 zodpověděli emocionální Stroopův test, v němž identifikovali barvu neutrálních či záporně laděných slov, která popisovala positivní, negativní či nijaké příznaky schizofrenie. Výsledky Studie 1 naznačily: a) že osoby se schizofrenií rozpoznávají hudební emoce s obdobnou přesností jako osoby bez schizofrenie, b) že projevují asociaci mezi vnímanou a prožívanou složkou hudební emoce s obdobnou silou, a c) že vnímají a prožívají hudební emoce s vyšší intenzitou....THE EMOTION-PARADOX 1 Abstract The emotion-paradox in schizophrenia describes a dissociation between the grossly impaired perception of emotion and relatively preserved experience thereof. Most posit that the emotion-paradox arises from a generalized emotion perception impairment. Others counter that it represents an artefact of methodological restrictions or a separate dissociation between explicit and implicit emotion. This thesis aimed to explain the emotion-paradox in schizophrenia and resolve the competing interpretations of its root. Two studies were conducted to this end. The studies drew from the same sample, including 45 persons with schizophrenia of various symptomatology, and 45 controls with no psychiatric anamnesis or familial history of schizophrenia. The groups did not differ in age, gender, education or music education. In Study 1, the participants listened to musical stimuli and rated their perception and experience of the valence and arousal that these stimuli relayed. In Study 2, the participants completed a newly developed emotional Stroop task, in which they identified the colour of a series of neutral and negative descriptors of positive, negative, or no symptoms of schizophrenia. Findings of Study 1 indicated: a) that persons with schizophrenia recognize musical emotions as accurately...Department of Psychiatry First Faculty of Medicine and General University HospitalPsychiatrická klinika 1. LF UK a VFNFirst Faculty of Medicine1. lékařská fakult

Error Observation in Schizophrenia

Despite the pervasive and impairing nature of social difficulties in schizophrenia, the causes of these problems are not fully understood. It has been suggested that problems with cognitive functioning contribute to the social deficits of schizophrenia. However, little is known about the neural mechanisms that underlie cognitive processes directly linked to social dysfunction in schizophrenia. Recent studies of the mirror neuron system have focused on the error-related negativity (ERN), a negatively-deflected event-related brain potential that is elicited following the commission of an erroneous response. This study examined ERN activity in schizophrenia patients and psychiatrically healthy controls during performance and observation of a confederate performing a computerized flanker task. The lateralized readiness potential (LRP) allowed for a direct comparison of brain activation reflecting response readiness verses error signaling. Correlations between ERN activity during flanker observation, social cognition (i.e., theory of mind), and community social functioning were explored. Finally, correlations between verbal memory, executive functioning, and social functioning were examined and social cognition was explored as a mediator between neurocognition and social functioning. Results indicated that controls produced a robust ERN during execution of the flanker task, whereas ERN activity among patients was comparatively attenuated in amplitude. During observation, there were no significant group differences and no identifiable observation ERN; however, there was greater negative activity following error than correct trials in this condition for all participants. LRP activity did not parallel that of the ERN, supporting the differentiation of motor activity and error-related processing during observation. The only significant correlation to emerge between ERN activity and social cognition and social functioning was between occupational status and execution ERN activity among controls only. Unexpectedly, neurocognition and social functioning were negatively correlated in the patient group. Expectedly, these variables were positively correlated among controls. Therefore, regression analyses were conducted separately by group; however, neither neurocognition nor social cognition predicted a significant proportion of the variance in social functioning. Despite limitations, this research is discussed as a starting point for integrating the study of psychophysiological activity with social behavior and functioning, particularly in a clinical population with pronounced social deficits

Verbal and nonverbal communication in schizophrenia - New insights from uni- and multimodal brain imaging

Socio-cognitive symptoms represent prominent and often strongly impairing deficits in patients with schizophrenia and they are tightly intertwined with dysfunctional communicative representations or systems. In particular, deficient verbal and nonverbal social information processing is associated with decreased functional outcome and prominent difficulties in everyday social interactions. Some specific aspects of verbal and nonverbal communication in schizophrenia have been thoroughly assessed by previous studies, particularly semantic priming at word level (verbal-cognitive domain) as well as face and facial emotion recognition (nonverbal-affective domain) and rather broad sociocognitive functions including Theory of Mind (ToM). However, only very little is known about disease-related alterations in more complex language functions, such as pragmatic (e.g. non-literal) language comprehension, or emotion processing from social cues other than the face, such as human body language. To this end, the present dissertation intended to investigate neurophysiological correlates of verbal and nonverbal socio-communicative (dys)functions in schizophrenia that have so far been rarely investigated using functional imaging, namely pragmatic language (verbalcognitive domain, 2 studies) and emotional body language (nonverbal-affective domain, 2 studies) processing. Neurophysiological activity was assessed by means of functional nearinfrared spectroscopy (fNIRS) measurements, either applied alone (unimodal imaging) or combined with electroencephalography (EEG; multimodal imaging). These specific neuroimaging methods have been chosen because they are characterised by high ecological validity and a relatively high flexibility regarding their applicability in varying contexts, implying a great potential of these techniques to assess social communicative functions in schizophrenia that are highly relevant for everyday social interactions. Taken together, the results obtained in the four studies revealed 1) that fNIRS measurements – either unimodally applied or combined with EEG – are useful to detect cortical activation associated with verbal-cognitive and nonverbal-affective information processing. 2) Patients with schizophrenia show significant alterations in these neurophysiological processes along with impaired recognition of pragmatic language (verbal-cognitive domain) and emotional body language (nonverbal-affective domain). The findings complement previous studies on more commonly assessed sociocommunicative dysfunctions in schizophrenia (altered semantic priming and facial expression perception). The present work provides a holistic overview over different social communication dysfunctions that may be apparent in patients suffering from schizophrenia and their accessibility via fNIRS and EEG-fNIRS measurements, respectively. Hereby, all project parts focused on an innovative implementation of neuroimaging methods that may be particularly promising for future directions in neuropsychiatric research. The findings are discussed in the light of contemporary models of pragmatic language comprehension as well as nonverbal social information processing. Moreover, they are integrated into current concepts of schizophrenia, particularly with respect to etiological models and neurocognitive frameworks as well as the endophenotype concept.Sozial-kognitive Symptome stellen ein markantes und häufig stark beeinträchtigendes Defizit von Patienten mit schizophrener Erkrankung dar, welches eng mit Dysfunktionen in Kommunikation und Interaktion verknüpft ist. Hierbei sind insbesondere Einschränkungen in der Verarbeitung verbal und nonverbal dargebotener sozialer Information mit einem verminderten generellen Funktionsniveau sowie deutlichen Schwierigkeiten bei alltäglichen sozialen Interaktionen assoziiert. Einige spezifische Teilbereiche verbaler und nonverbaler Kommunikation bei Schizophrenie wurden bereits in früheren Studien zum Teil ausführlich untersucht, wie beispielsweise semantische Bahnung (Priming) auf Wortebene (verbalkognitive Ebene), (emotionale) Gesichtsverarbeitung (nonverbal-affektive Ebene) sowie weniger scharf umgrenzte sozial-kognitive Funktionen einschließlich Theory of Mind (ToM). Bislang ist jedoch wenig bekannt über störungsbezogene Veränderungen komplexer Sprachverarbeitung, wie pragmatisches (z. B. nicht-wörtlich gemeintes) Sprachverstehen, oder der Verarbeitung von Emotionen auf Basis sozialer Reize, die nicht auf Gesichter beschränkt sind, wie beispielsweise menschliche Körpersprache. Die vorliegende Dissertation befasst sich daher mit der Untersuchung neurophysiologischer Korrelate solcher verbaler und nonverbaler kommunikativer (Dys-)Funktionen bei Schizophrenie, die bislang nur wenig mittels funktioneller Bildgebung untersucht worden sind. Hierbei werden zum einen pragmatische Sprache (verbal-kognitive Ebene) und zum anderen emotionale Körpersprache (nonverbal-affektive Ebene) fokussiert. Die Erfassung neurophysiologischer Aktivität erfolgt mithilfe der Methode der funktionellen Nahinfrarot-Spektroskopie (fNIRS), welche hierbei entweder allein (unimodale Messungen) oder in Kombination mit Elektroenzephalographie (EEG, multimodale Messungen) zum Einsatz kommt. Diese bildgebenden Verfahren wurden insbesondere aufgrund ihrer hohen ökologischen Validität und flexiblen Anwendbarkeit in verschiedensten Untersuchungs-Situationen ausgewählt, welche ein hohes Potential beider Methoden zur validen und ökonomischen Untersuchung alltagsrelevanter kommunikativer Funktionen bei Schizophrenie nahe legen. Zusammengefasst ergaben die in den vier Studien erbrachten Ergebnisse folgendes Bild: (1) fNIRS Messungen, sowohl uni- als auch multimodal (hier: in Kombination mit EEG) angewendet, bilden eine nützliche Methode zur realitätsnahen Erfassung kortikaler Aktivierung, die mit verbal-kognitiver und nonverbal-affektiver Informationsverarbeitung in Zusammenhang stehen. (2) Patienten mit Schizophrenie zeigen signifikante Veränderungen dieser neurophysiologischen Prozesse, welche behavioral mit einem verminderten pragmatischem Sprachverstehen (verbal-kognitive Ebene) sowie Einschränkungen im Erkennen emotionaler Körpersprache (nonverbal-affektive Ebene) einhergehen. Diese Befunde ergänzen frühere Studien zu weniger komplexen, aber bislang häufiger untersuchten sozio-kommunikativen Dysfunktionen bei Schizophrenie (z. B. verändertes semantisches Priming sowie beeinträchtigte Verarbeitung von Gesichtsausdrücken). Die Befunde werden vor dem Hintergrund theoretischer Modelle zum pragmatischen Sprachverstehen sowie der Verarbeitung nonverbaler sozialer Information diskutiert. Darüber hinaus werden die Ergebnisse in aktuelle Konzepte der Schizophrenie integriert, insbesondere im Hinblick auf äthiologische Modelle und neurokognitive Erklärungsansätze der Erkrankung. Zudem wird eine Einordnung der hier untersuchten kommunikativen Funktionen in das Endophänotypenkonzept versucht

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