Snakes are probably the best example of evolutionarily life-threatening stimulus as they have been one of the first predators of primates and mammals in general. In recent years, it has been shown that snake images produce specific behavioral and electrophysiological reactions in humans, provoking enhanced brain activity over the occipital cortex compared with pictures of other animals. The present study investigated the hypothesis that the response to snake images is independent from awareness. Subjects (n=27) were asked to observe pictures of threatening and non-threatening animal stimuli, presented rapidly and in random order on a screen. Awareness level was manipulated using 4 different conditions of backward masks. Event Related Potentials (ERPs) showed that activity over the occipital cortex was clearly more pronounced for snake images than for the other images, but only in unmasked condition. / Ormar är sannolikt ett av de bästa exemplen på ett evolutionärt livshotande stimuli då de utgjort ett av de första rovdjuren för primater och däggdjur i allmänhet. På senare år har man visat att bilder på ormar producerar specifika beteenden och elektrofysiologiska reaktioner hos människan, och ökad hjärnaktivitet i occipitalkortex jämfört med bilder på andra djur. Föreliggande studie undersökte hypotesen att responsen till ormbilder är oberoende från medvetandet. Deltagarna (n=27) ombads observera bilder på hotfulla respektive icke-hotfulla djurstimuli som presenterades snabbt och i slumpvis ordning på skärmen. Nivå av medvetande manipulerades genom att använda fyra olika betingelser av bakåt maskering. Event-relaterade potentialer (ERPs) visade att aktiviteten över occipitalkortex var betydligt mer uttalad för ormbilder jämfört med andra bilder, men bara i den icke-maskerade betingelsen.

Current research shows that emotions have an important role in guiding attention and cognitions especially when the emotional stimuli are affective. Load theory proposes that when the perceptual load on attention is sufficiently high, irrelevant emotional stimuli is no longer attended to and thus will not produce a distracting effect. In this study 18 participants performed two discrimination tasks where their attention was manipulated spatially. To investigate the effect of spatial attention on ERP components, emotional pictures in 14 different semantic categories were shown while EEG was recorded. The results indicate that a successful perceptual load was achieved, reflected in the behavioral data that show there was a clear difference in performance between tasks. Further the results indicate that a strong effect was achieved in the mean amplitudes of both EPN and LPP corresponding to the semantic categories of pictures. Critically directing the attention to the periphery while emotionally salient pictures were presented attenuated the mean amplitude of both EPN and LPP.

Homophobia in men may be, in part, due to reaction formation rooted in unacceptable same-sex attraction. Previous studies have not confirmed a covert same-sex attraction in homophobic men, which is necessary for a reaction formation theory of homophobia. This study sought to reveal possible covert same-sex attraction in homophobic men. In this study, heterosexual and homosexual male erotic images were presented in a passive S1/S2 stimulus prediction design to 48 self-identified heterosexual participants, grouped by homophobia. Three event-related potential responses related to valenced emotional processing were examined: the medial frontal negativity (MFN), the late positive potential (LPP), and the positive frontal slow wave (FSW). While homophobic men have a larger FSW in response to erotics across the board, F(1,46) = 3.88, p = .055, no significant interactions between homophobia and image content were found. As such, homophobic men may have more interest in erotic images in general, but this study does not demonstrate that homophobic men find homosexual erotics appetitive.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Die Blickrichtung und ihre Richtung sind wichtige nonverbale Hinweise für die Etablierung von sozialen Interaktionen und die Wahrnehmung von emotionalen Gesichtsausdrücken bei anderen. Ob der Blick direkt auf den Betrachter gerichtet ist (direkter Blick) oder abgewendet (abgewandter Blick), beeinflusst unsere soziale Aufmerksamkeit und emotionale Reaktionen. Dies deutet darauf hin, dass Emotionen und Blickrichtung informative Werte haben, die sich möglicherweise in frühen oder späteren Stadien der neurokognitiven Verarbeitung interagieren. Trotz theoretischer Grundlage, der geteilten Signal-Hypothese (Adams & Kleck, 2003), gibt es einen Mangel an strukturierten elektrophysiologischen Untersuchungen zu den Wechselwirkungen zwischen Emotionen und Blickrichtung sowie ihren neuronalen Korrelaten und wie sie sich in verschiedenen Bevölkerungsgruppen unterscheiden. Um diese Lücke zu schließen, verwendete diese Doktorarbeit ereigniskorrelierte Hirnpotentiale (ERPs), um die Reaktionen auf emotionale Ausdrücke und Blickrichtung in einem neuen Paradigma zu untersuchen, das statischen und dynamischen Blick mit Gesichtsausdrücken kombiniert. Es wurden drei verschiedene Populationen untersucht. Studie 1 untersuchte in einer normalen Stichprobe die Amplituden der ERP-Komponenten, die durch die erstmalige Präsentation von Gesichtern und nachfolgende Änderungen der Blickrichtung in der Hälfte der Durchgänge ausgelöst wurden. In Studie 2 wurden aufgrund der atypischen Gesichtsverarbeitung und verminderten Reaktionen auf Augenblick beim Autismus die ERPs und Augenbewegungen bei zwei Stichproben von Kindern mit unterschiedlichem Schweregrad ihrer Autismusmerkmale untersucht. In Studie 3 wurde in einer großen Stichprobe die vermutlich erhöhte Sensitivität bei der Emotionsverarbeitung und Reaktion auf Augenblick bei Müttern im postpartalen Zeitraum mit besonderem Fokus auf die Gesichter von Säuglingen untersucht. Zusammenfassend zeigen die Ergebnisse der drei Studien, dass in sozialen Interaktionen die emotionalen Effekte von Gesichtern durch die dynamische Blickrichtung moduliert werden. / The eye gaze and its direction are important and relevant non-verbal cues for the establishment of social interactions and the perception of others’ emotional facial expressions. Gaze direction itself, whether eyes are looking straight at the viewer (direct gaze) or whether they look away (averted gaze), affects our social attention and emotional response. This implies that both emotion and gaze have informational values, which might interact at early or later stages of neurocognitive processing. Despite the suggestion of a theoretical basis for this interaction, the shared signal hypothesis (Adams & Kleck, 2003), there is a lack of structured electrophysiological investigations into the interactions between emotion and gaze and their neural correlates, and how they vary across populations. Addressing this need, the present doctoral dissertation used event-related brain potentials (ERPs) to study responses to emotional expressions and gaze direction in a novel paradigm combining static and dynamic gaze with facial expressions. The N170 and EPN were selected as ERP components believed to reflect gaze perception and reflexive attention, respectively. Three different populations were investigated. Study 1, in a normal sample, investigated the amplitudes of the ERP components elicited by the initial presentation of faces and subsequent changes of gaze direction in half of the trials. In Study 2, based on the atypical face processing and diminished responses to eye gaze in autism, the ERPs and eye movements were examined in two samples of children varying in the severity of their autism traits. In Study 3, In a large sample, I addressed the putatively increased sensitivity in emotion processing and response to eye gaze in mothers during their postpartum period with a particular focus on infant's faces. Taken together, the results from three studies demonstrate that in social interactions, the emotional effects of faces are modulated by dynamic gaze direction.

The aim of the present study was to study the occurrence of scavenging behavior among different species and strains of entomopathogenic nematodes. Another part of the study was focused on scavenging of the selected entomopathogenic nematodes in insects killed by various non-native strains of Xenorhabdus bovinenii. Further aim was to investigate the interspecific competition of the selected entomopathogenic nematodes with the nematode Oscheius myriophila for dead hosts. The final aim was the search for possible toxicity of the selected X. bovienii strains against nematode Oscheius myriophila.

Depuis la fin des années quatre-vingt-dix, les technologies de l'information et de la communication (TIC) envahissent tous les secteurs de la vie sociale, professionnelle ou culturelle. Pour éviter qu'un fossé numérique se creuse, les espaces publics numériques (EPN) ont été créés dès 1998 afin de permettre à toutes les personnes qui le souhaitent de bénéficier d'un accès accompagné aux TIC. Ces espaces ont aujourd'hui, malgré eux, la mission délicate d'accompagner certains publics qui se trouvent dans l'obligation d'utiliser ces outils numériques, en l'occurrence les demandeurs d'emploi pour lesquels l'usage d'Internet et autres logiciels sont devenus des outils indispensables à leurs démarches de retour à l'emploi. L'objectif de cette recherche est d'identifier les fonctions que jouent les EPN auprès de ces publics qui sont de plus en plus nombreux à fréquenter ces espaces. Face à un système de retour à l'emploi qui semble privilégier une logique de traitement des dossiers sur des critères d'efficacité quantitatifs, ce travail montre comment le public des disqualifiés sociaux s'approprient ces lieux de diffusion du numérique pour développer des usages des TIC et des stratégies d'empowerment afin de se libérer de l'assistance exercée par l'institution. Au-delà du rapport à l'emploi, cette recherche s'intéresse également à la fonction d'espace anonyme que remplit l'EPN. Elle porte une analyse sur la manière dont les publics s'approprient ces espaces pour échapper aux phénomènes de stigmatisation d'un statut " dévalorisé " que génère leur situation. Ce travail de recherche participe à la réflexion sur l'inclusion numérique et sur la manière dont s'articulent les dispositifs de retour à l'emploi et ceux qui mettent en place des actions autour des outils numériques.

This dissertation aims to investigate the correlations of visual evoked potentials during the experimental process of serial passive affective priming. The aim of this dissertation is to identify partial processes of affective perception, which are influenced by relations to previous affective priming stimulation. The research is designed as a laboratory EEG experiment, which uses affective priming techniques, particularly its sequential passive multimodal (auditory-visual) variation. The research experimentally manipulates emotional characteristics of stimuli that are constructed on the basis of the dimensional theory. As a starting dimension, arousal was chosen that is equivalent to psychic activation connected to reactions to stimuli. The study was carried out in the PF JČU neurological laboratory using a 64 channel EEG Biosemi Active II. Probands was selected from the JČU students, whose brain electrical activity was measured during an exposure to affective stimuli from international emotional elicitation databases. Records from 29 people were used. The independent variable used was the variation of priming and arousal characteristics of the priming stimulus from the affective melodies database (Eerola &Vuoskoski, 2010) and the arousal characteristics of a visual stimuli (Marchewka et al., 2014). Visual perception is the most explored ERP process, therefore the differences between the results of this dissertation study and comparative studies can be the basis for interpreting the mechanism of contextual affective transmission. Time progress and activation reactions are modulated based on experimental conditions and the dependent variables are the differences of latency and amplitude of individual components of evoked potentials, which represent partial psychological processes. The use of sound as priming stimulus together with a high interstimulus interval decreases the conflict between perceptual processes in selective attention. The differences in processes of visual perception according to affective arousal characteristics of stimuli suggest a parietally increased early posterior negativity (EPN) and late positive potentials (LPP) of high-arousal stimuli in comparison to low-arousal stimuli. Signs of EPN manifest as indicators for prioritization of attention in comparison with actively motivating stimuli. The priming effect manifested in P1 and N1 components occipitoparietally and in N2 centroparietally, which suggest stronger negativity of EPN in the case of previous priming. LPP increase for the priming condition was there only for high-arousal stimuli. The cause for higher activation for priming conditions in P1 and N1 is unknown, it is a case of premature latency for possible explanation using the evaluation mechanism. The results showcase the influence of conflict between processes of attention or the alternative interpretations of affective priming based on the influence of context on the formation of evaluative conclusions. The priming effects in LPP show a lower later parietal activation of primed stimuli which can be connected to their previous increased activation as a part of early and medium latency component.

Dopamine agonist therapy and deep brain stimulation (DBS) are both linked to increased impulsivity in Parkinson’s disease (PD), but the underlying mechanisms remain unclear. We trained intact and PD-like rats on a rat gambling task (rGT) measuring impulsive choice and premature responding. Animals were then retested with/without treatment, pramipexole (PPX) or DBS, administered chronically prior to rGT testing. Early PD-like rats did not exhibit major differences in rGT performance or treatment response. Our work suggests that DBS and PPX are not intrinsically linked with increases in impulsivity. Neither DBS nor PPX disrupted gambling-like behaviour in our paradigm, while differential effects on premature and perseverant responding in the task were observed with treatment. Based on our findings, the previously reported ability of PPX to increase impulsive choice might not be mediated by the dopamine D3 receptor. Interestingly, our work suggests that the effects of STN-DBS on impulse control might be amplitude-dependent.