Diagnostic information use to understand brain mechanisms of facial expression categorization

Proficient categorization of facial expressions is crucial for normal social interaction. Neurophysiological, behavioural, event-related potential, lesion and functional neuroimaging techniques can be used to investigate the underlying brain mechanisms supporting this seemingly effortless process, and the associated arrangement of bilateral networks. These brain areas exhibit consistent and replicable activation patterns, and can be broadly defined to include visual (occipital and temporal), limbic (amygdala) and prefrontal (orbitofrontal) regions. Together, these areas support early perceptual processing, the formation of detailed representations and subsequent recognition of expressive faces. Despite the critical role of facial expressions in social communication and extensive work in this area, it is still not known how the brain decodes nonverbal signals in terms of expression-specific features. For these reasons, this thesis investigates the role of these so-called diagnostic facial features at three significant stages in expression recognition; the spatiotemporal inputs to the visual system, the dynamic integration of features in higher visual (occipitotemporal) areas, and early sensitivity to features in V1. In Chapter 1, the basic emotion categories are presented, along with the brain regions that are activated by these expressions. In line with this, the current cognitive theory of face processing reviews functional and anatomical dissociations within the distributed neural “face network”. Chapter 1 also introduces the way in which we measure and use diagnostic information to derive brain sensitivity to specific facial features, and how this is a useful tool by which to understand spatial and temporal organisation of expression recognition in the brain. In relation to this, hierarchical, bottom-up neural processing is discussed along with high-level, top-down facilitatory mechanisms. Chapter 2 describes an eye-movement study that reveals inputs to the visual system via fixations reflect diagnostic information use. Inputs to the visual system dictate the information distributed to cognitive systems during the seamless and rapid categorization of expressive faces. How we perform eye-movements during this task informs how task-driven and stimulus-driven mechanisms interact to guide the extraction of information supporting recognition. We recorded eye movements of observers who categorized the six basic categories of facial expressions. We use a measure of task-relevant information (diagnosticity) to discuss oculomotor behaviour, with focus on two findings. Firstly, fixated regions reveal expression differences. Secondly, by examining fixation sequences, the intersection of fixations with diagnostic information increases in a sequence of fixations. This suggests a top-down drive to acquire task-relevant information, with different functional roles for first and final fixations. A combination of psychophysical studies of visual recognition together with the EEG (electroencephalogram) signal is used to infer the dynamics of feature extraction and use during the recognition of facial expressions in Chapter 3. The results reveal a process that integrates visual information over about 50 milliseconds prior to the face-sensitive N170 event-related potential, starting at the eye region, and proceeding gradually towards lower regions. The finding that informative features for recognition are not processed simultaneously but in an orderly progression over a short time period is instructive for understanding the processes involved in visual recognition, and in particular the integration of bottom-up and top-down processes. In Chapter 4 we use fMRI to investigate the task-dependent activation to diagnostic features in early visual areas, suggesting top-down mechanisms as V1 traditionally exhibits only simple response properties. Chapter 3 revealed that diagnostic features modulate the temporal dynamics of brain signals in higher visual areas. Within the hierarchical visual system however, it is not known if an early (V1/V2/V3) sensitivity to diagnostic information contributes to categorical facial judgements, conceivably driven by top-down signals triggered in visual processing. Using retinotopic mapping, we reveal task-dependent information extraction within the earliest cortical representation (V1) of two features known to be differentially necessary for face recognition tasks (eyes and mouth). This strategic encoding of face images is beyond typical V1 properties and suggests a top-down influence of task extending down to the earliest retinotopic stages of visual processing. The significance of these data is discussed in the context of the cortical face network and bidirectional processing in the visual system. The visual cognition of facial expression processing is concerned with the interactive processing of bottom-up sensory-driven information and top-down mechanisms to relate visual input to categorical judgements. The three experiments presented in this thesis are summarized in Chapter 5 in relation to how diagnostic features can be used to explore such processing in the human brain leading to proficient facial expression categorization

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

Fostering advances to neuropsychological assessment based on the Research Domain Criteria: The bridge between cognitive functioning and physiology

Objectives: The current review aimed to explore the advances in neuropsychological assessment in light of a recent research framework designed to improve our knowledge on mental health – the Research Domain Criteria (RDoC). Methods: RDoC proposals on neuropsychological tests were reviewed across the RDoC cognitive systems domain. The focus is on the physiological unit of analysis and the potential applications are illustrated given the functional relevance of RDoC constructs to psychopathological and neurological conditions. Results: The advances in neuropsychology anchored in RDoC are not observable in terms of innovative paradigms, but rather in the neurobiological correlates that may be obtained from the classical neuropsychological tasks. The behavior unit of analysis may be integrated with physiological outcomes while mapping distinct cognitive constructs simultaneously. Conclusions: Under the aegis of RDoC, the integration of multiple levels of analysis allows to obtain a more detailed and complete neuropsychological characterization with high potential to be translated into better intervention strategies.info:eu-repo/semantics/publishedVersio

Psychologie und Gehirn 2007

Die Fachtagung "Psychologie und Gehirn" ist eine traditionelle Tagung aus dem Bereich psychophysiologischer Grundlagenforschung. 2007 fand diese Veranstaltung, die 33. Jahrestagung der „Deutschen Gesellschaft für Psychophysiologie und ihre Anwendungen (DGPA)“, in Dortmund unter der Schirmherrschaft des Instituts für Arbeitsphysiologie (IfADo) statt. Neben der Grundlagenforschung ist auch die Umsetzung in die Anwendung erklärtes Ziel der DGPA und dieser Tradition folgend wurden Beiträge aus vielen Bereichen moderner Neurowissenschaft (Elektrophysiologie, bildgebende Verfahren, Peripherphysiologie, Neuroendokrinologie, Verhaltensgenetik, u.a.) präsentiert und liegen hier in Kurzform vor

EEG Korrelate und Gedächtnisleistungen bei spontanen fazialen Selbstberührungen

Die Beschreibung spontaner Berührungen des eigenen Körpers findet sich bereits in der psychologischen Forschungsliteratur der 1930er Jahre. Das spontane Berühren des eigenen Gesichts tritt Studien zufolge häufiger auf als das spontane Berühren anderer Körperteile. Trotz jahrzehntelanger Forschung sowie aktueller Präsenz des Themas im Zusammenhang mit der COVID-19-Pandemie, sind zentrale Fragen zu Auslösemechanismen und psychophysiologischen Funktionen von spontanen fazialen Selbstberührungen bislang unbeantwortet. Die vorliegende Dissertation liefert anhand neurophysiologischer sowie behavioraler Daten neue Erkenntnisse zu Funktionen von spontanen fazialen Selbstberührungen und trägt damit zur Weiterentwicklung der Theorie dieses Verhaltens bei

Reductions in negative automatic thoughts in students attending mindfulness tutorials predicts increased life satisfaction

University education confronts students with stressful developmental challenges that can lead to mental health problems. Innovative programs must address an increasing prevalence of these problems but are impeded by the high costs involved. In this study, thirty-nine undergraduate students attended weekly one hour mindfulness meditation tutorials during a single (14 week) semester. Tutorials involved 40 minutes of guided meditation, followed by open-ended discussions on mindfulness and related scientific research. Multiple regression analysis tested associations between self-reported changes in mindfulness, in negative automatic thoughts and in satisfaction with life.Reductions in automatic thoughts accounted for a significant proportion of variance in life satisfaction and decreases in automatic thoughts were associated with an increased life satisfaction. This finding suggests guided meditation tutorials merit consideration in promoting student mental health on university campuses.Social Sciences and Humanities Research Council (SSHRC

Reductions in Negative Automatic Thoughts in Students Attending Mindfulness Tutorials Predicts Increased Life Satisfaction

University education confronts students with stressful developmental challenges that can lead to mental health problems. Innovative programs must address an increasing prevalence of these problems but are impeded by the high costs involved. In this study, thirty-nine undergraduate students attended weekly one hour mindfulness meditation tutorials during a single (14 week) semester. Tutorials involved 40 minutes of guided meditation, followed by open-ended discussions on mindfulness and related scientific research. Multiple regression analysis tested associations between self-reported changes in mindfulness, in negative automatic thoughts and in satisfaction with life.Reductions in automatic thoughts accounted for a significant proportion of variance in life satisfaction and decreases in automatic thoughts were associated with an increased life satisfaction. This finding suggests guided meditation tutorials merit consideration in promoting student mental health on university campuses.

Temporal dynamics of target selection and distractor suppression mechanisms in the right Frontal Eye Field

The ability of the human brain to selectively attend to relevant information while ignoring irrelevant distraction is essential for the successful completion of everyday tasks. The present PhD project aimed to unravel the temporal dynamics of target selection and distractor suppression in the Frontal Eye Field (FEF), a key node in the dorsolateral attention network. Previous research (Lega et al., 2019) had assessed the contribution of both IPS and FEF to the deployment of visuo- spatial attention by means of 10 Hz TMS during a visual search task. The stimulation was delivered in a post-stimulus epoch from 100 to 300 ms, considered crucial for attentional computations in visual search. This study found that the TMS protocol improved distractor suppression mechanisms, reducing the cost engendered by salient but task-irrelevant distractors. To further clarify the temporal contribution of right FEF to distractor suppression, two experiments were carried out. Experiment 1 applied single-pulse TMS over right FEF at three different time points, 50, 200 or 350 ms after search array onset. Experiment 2 aimed to exert a stronger TMS effect over right FEF while maintaining a temporal-punctate approach. It applied trains of triple-pulse TMS at 20 Hz over right FEF in three different time windows: from -50 to 50 ms (T1), from 100 to 200 ms (T2) and from 250 to 350 ms (T3) after the search array onset. While Experiment 1 showed only a general, time-unspecific and quasi- significant effect of stimulation over response times, Experiment 2 revealed that stimulation at T2 (100-200 ms) was associated with an increase of the distractor cost, specifically for distractors located contralaterally to the stimulation site. These findings support the role of right FEF in suppressing distractions from salient but irrelevant stimuli and suggest that TMS may activate/inhibit the neural network that regulates and limits interference from such distractions. Further research is needed to precisely assess the physiological effects of different TMS protocols of the right FEF and its influence on attentional computation