EEG analysis for understanding stress based on affective model basis function

Coping with stress has shown to be able to avoid many complications in medical condition. In this paper we present an alternative method in analyzing and understanding stress using the four basic emotions of happy, calm, sad and fear as our basis function. Electroencephalogram (EEG) signals were captured from the scalp of the brain and measured in responds to various stimuli from the four basic emotions to stimulating stress base on the IAPS emotion stimuli. Features from the EEG signals were extracted using the Kernel Density Estimation (KDE) and classified using the Multilayer Perceptron (MLP), a neural network classifier to obtain accuracy of the subject’s emotion leading to stress. Results have shown the potential of using the basic emotion basis function to visualize the stress perception as an alternative tool for engineers and psychologist. Keywords: Electroencephalography (EEG), Kernel Density Estimation (KDE), Multi-layer Perceptron (MLP), Valance (V), Arousal (A

Verarbeitung emotionaler Reize bei Personen mit einer Zwangsstörung

Trotz zahlreicher Untersuchungen lässt sich bei der Zwangsstörung noch kein einheitliches, alle Befunde integrierendes Krankheitsmodell formulieren. Die Verarbeitung von emotionalen Reizen könnte bei Personen mit Zwangsstörungen verändert sein. Dies trägt möglicherweise zur Entwicklung und Aufrechterhaltung der Störung bei. Das Ziel der vorliegenden Arbeit war es, spezifische Komponenten dieser Verarbeitung zu untersuchen. Zuerst wurde in zwei unterschiedlichen Studien überprüft, ob die Orientierung der Aufmerksamkeit zu neuen Reizen bei Patienten mit Zwangsstörungen verstärkt ist. Zu diesem Zweck wurden durch neue Reize evozierte Potentiale im Elektroenzephalogramms (EEG) gemessen. Anschließend wurde in einer Studie überprüft, ob das Verhältnis der Aktivierungen von dem Vermeidungs- zum Annäherungssystem bei den Betroffenen verändert ist. Dies lässt sich an Hand der Ermittlung der hemisphärischen Verteilung von Alpha-Wellen in frontalen Hirnregionen feststellen. Die Ergebnisse der ersten beiden Studien ergaben, dass Patienten unabhängig vom emotionalen Kontext eine stärkere Aufmerksamkeitshinwendung zu neuen Reizen zeigen (Studie 1), was allerdings nicht beobachtet wurde, wenn die neuen Reize innerhalb des Aufmerksamkeitsfokus lagen (Studie 2). Dieses Ergebnis wurde als überaktives Gefahrenerkennungssystem bei Patienten interpretiert. Weiterhin ließ sich feststellen, dass Patienten im Vergleich zu gesunden Kontrollen in frontalen Hirnregionen eine Verlagerung der Alpha Asymmetrie zur linken Gehirnhemisphäre aufwiesen (Studie 3). Dieser Befund wurde unabhängig von einer Stimulierung durch emotionale Reize gemacht. Er lässt sich als stärkere Aktivierung des Vermeidungs- im Verhältnis zum Annäherungssystem deuten. Zusammengefasst zeigte sich bei Patienten mit Zwangsstörungen eine veränderte Verarbeitung von emotionalen Reizen. Aus diesen Befunden können spezifische Empfehlungen für die Behandlung der Störung abgeleitet werden.It is so not possible to formulate a disease model of obsessive-compulsive disorder (OCD) that integrates all the results of the many studies carried out. The neural processing of emotional stimuli might be altered in people with OCD. This might play an important role in the development and maintenance of OCD. The present work aimed to investigate specific components of the neural processing of emotional stimuli. The first two studies examined if the orienting of attention towards novel stimuli is enhanced in patients with OCD. For this purpose the event-related brain potentials evocated by novel stimuli in the electroencephalogram were recorded. The third study tested if the relationship between the withdrawal-avoidance mode and the approach mode of the motivational brain system is altered in OCD patients. This can be assessed by the hemispheric distribution of alpha power in frontal brain regions. The results of the first two studies showed that the orienting of attention towards novel stimuli is enhanced in patients with OCD independently of the emotional context condition (study 1), which could not be observed if the novel stimuli were listened to in active attentional mode (study 2). This was interpreted as a hypersensitive threat detection system. Further, it was found that patients showed a shift of frontal alpha activity to the left hemisphere compared to healthy control subjects (study 3). This result was independent of the viewing of emotional stimuli. It can be concluded that the avoidance mode is relatively increased in patients with OCD. Taken together, patients showed an altered neural processing of emotional stimuli. Specific recommendations for he treatment of the disorder can be drawn out of them

Attachment classification, psychophysiology and frontal EEG asymmetry across the lifespan: a review

In recent years research on physiological response and brain reactivity in different patterns of infant and adult attachment has increased. We review research findings regarding associations between attachment classifications and reactivity of the prefrontal cortex, the autonomic nervous system and the hypothalamic-pituitary-adrenocortical axis. Studies indicate that insecure attachment is related to a heightened adrenocortical activity, heart rate and skin conductance in response to stress, which is consistent with the hypothesis that attachment insecurity leads to impaired emotion regulation. Research on frontal EEG asymmetry also shows a clear difference in the emotional arousal between the attachment groups evidenced by specific frontal asymmetry changes. Furthermore, we discuss neurophysiological evidence of attachment organization and present up-to-date findings of EEG-research with adults. Based on the overall patterns of results presented in this article we identify some major areas of interest and directions for future research

Social processing, frontal asymmetries and the effect of emotion based disorders upon brain functioning and behaviour in infancy

This thesis had three main aims, firstly to explore the experience of auditory social and non-social stimuli upon infants brain functioning. Secondly to explore the role of the prefrontal cortex (PFC) in social and non-social visual processing and anxiety. Lastly, to investigate the effect of a mother's depression upon infant behaviour. Chapter 1 explored the literature surrounding social and non-social processing in infancy, the role of the prefrontal cortex (PFC) and the effect of depression upon mother-infant interactions and brain functioning. Chapter 2 described the methods used within this thesis. Chapter 3 investigated the impact of speech and non-speech processing upon infant brain functioning. Social and non-social processing in the PFC in infancy was explored in chapter 4. Chapter 5 looked at the impact of a mothers anxiety upon infant frontal asymmetries. Meta-analyses were conducted in Chapter 6 to investigate differences in behaviour in the still-face paradigm between infants of depressed and infants of non-depressed mothers. Chapter 7 summarised the results of the thesis in terms of findings, implications of the results, directions for future work and limitations of the current thesis

Noise sensitivity in the function and structure of the brain

Exposure to noise has a negative influence on human health, including an increased occurrence of cardiovascular diseases. Susceptibility to the harmful effects of noise can be further moderated by a personal trait called noise sensitivity (NS). It is not understood what makes some individuals more sensitive to noise than others. So far, the research on this topic has been largely limited to perceptual and population studies. The aim of this thesis was to broaden the understanding of NS by addressing its biological mechanisms. Thus, this thesis investigated the neuroanatomical correlates of NS and its effects on auditory processing. The thesis consists of three studies. The first study examines whether NS can be developed as the result of musical training (Study I). The other two studies investigate whether NS is reflected in the functioning of the central auditory system (Study II) and whether it is related to the morphology of cortical and subcortical brain structures (Study III). The research was conducted using questionnaires, combined magneto- and electroencephalography (MEG/EEG) and magnetic resonance imaging (MRI). The findings of this thesis suggest that NS moderates how and why individuals listen to music. However, NS is not associated with musical training and thus does not seem to relate to fine perceptual skills (Study I). An investigation of the central auditory processing in Study II, however, revealed compromised sound feature encoding and automatic discrimination skills in noise-sensitive individuals. Study III showed that NS is also associated with the structural organization of the brain. Noise-sensitive individuals were found to have enlarged volumes of the auditory cortical areas and hippocampus as well as thicker right anterior insular cortex. These results suggest that NS is related to the structures involved with auditory perceptual, emotional, and interoceptive processing. Overall, this thesis proposes that NS is not merely an attitudinal phenomenon but instead has underlying neuronal mechanisms.Altistuminen melulle vaikuttaa negatiivisesti ihmisten terveyteen, muun muassa kohonneena riskinä sydän- ja verisuonitaudeille. Meluherkkyys on persoonallisuuden piirre, joka voi vaikuttaa alttiuteen melusta koituville haitoille. Syytä sille, mikä tekee toisista herkempiä melulle, ei tiedetä. Tähän mennessä asiaa on selvitetty lähinnä melun havaintokykyä ja sen esiintymistä väestössä kartoittavien tutkimusten avulla. Tämän väitöskirjan tavoitteena oli lisätä tietoa meluherkkyyden biologisista mekanismeista. Väitöskirjassa tutkittiin meluherkkyyteen liittyviä aivojen rakenteita sekä meluherkkyyden vaikutusta kuulotiedon käsittelyyn. Väitöskirja koostuu kolmesta osatutkimuksesta. Ensimmäisessä tutkimuksessa selvitettiin, voiko meluherkkyys kehittyä musiikin harjoittelun seurauksena (Tutkimus I). Kahdessa muussa osatutkimuksessa selvitettiin, heijastuuko meluherkkyys aivojen kuulojärjestelmän toimintaan (Tutkimus II), ja liittyykö se aivokuoren ja sen alaisiin rakenteisiin (Tutkimus III). Tutkimukset suoritettiin käyttämällä kyselytutkimuksia, yhdistettyä aivosähkökäyrää ja sen magneettista vastinetta, eli elektro- ja magnetoenkefalografiaa (EEG/MEG), sekä aivojen magneettikuvausta (MRI). Tämän väitöskirjan tulosten mukaan meluherkkyys vaikuttaa siihen, miten ja miksi ihmiset kuuntelevat musiikkia. Meluherkkyys ei kuitenkaan liity musiikin harjoitteluun eikä täten liene yhteydessä hienovaraiseen kuulohavaintokykyyn (Tutkimus I). Tutkimus II kuitenkin paljasti, että äänten erottelukyky ja äänipiirteiden koodaus aivoissa on heikentynyttä meluherkillä yksilöillä. Tutkimuksessa III osoitettiin, että meluherkkyys on myös yhteydessä aivorakenteiden järjestäytymiseen. Meluherkillä löydettiin suurentunut kuuloaivokuoren ja hippokampuksen tilavuus sekä paksumpi oikean etuaivopuoliskon aivosaari. Näiden tulosten mukaan meluherkkyys on yhteydessä rakenteisiin, jotka osallistuvat äänten havaitsemiseen sekä niiden tunneperäistä ja elimellistä tietoa välittävään tiedonkäsittelyyn. Kaiken kaikkiaan tässä väitöskirjassa esitetään, että meluherkkyydellä on hermostollista taustaa eikä se ole pelkästään negatiivinen asenne melua kohtaan

Physiological and psychological assessment of schizophrenia and affective disorders

The study examined data on the physiological and psychological changes which occur in schizophrenia and the affective disorders. The main physiological variable studied was the P3, a component of Event Related Potentials (ERPs), which has been hypothesized to reflect a manifestation of information processing involving the matching of incoming stimuli with the subject's cognitive set. Information processing deficits have also been implicated in schizophrenia and in the affective disorders.The specific aims were:a) to compare the P3 components of the ERPs in clinical groups (schizophrenia, bipolar depression and unipolar depression) and non - patient groups (normal controls and relatives of schizophrenic patients)b) to identify dysfunctional cognitive styles which correlate with abnormalities in P3 latency and amplitudec) to consider whether the cognitive and physiological abnormalities correlate with structural change measured by Magnetic Resonance Imaging (MRI) in the schizophrenic patientsd) to consider whether another physiological variable (Eye Tracking Dysfunction, ETD) which is also involved in information processing differentiates the groups and correlates with cognitive function and structural change.Three studies were conducted. In the first study, physiological responses (P3 and ETD) and psychological performance related to the formation and use of cognitive sets were identified in 24 schizophrenic, 10 bipolar manic, 10 bipolar depressed, 10 unipolar depressed and 24 control subjects. P3 latencies were found to be significantly different in the schizophrenic and bipolar groups compared with the control subjects. Deficits in cognitive function in these patient groups correlated significantly with increased P3 latencies, indicating that schizophrenic and bipolar subjects experience dysfunctions in cognitive set which are reflected in their physiological funtioning. Two sub -groups were identified in the schizophrenic population: one group showed a strong correlation between P3 latency and tests which are sensitive to frontal lobe function, and the other group showed a significant correlation between P3 latency and performance in verbal recall.In the second test, MRI measures of structural change were correlated with physiological and cognitive scores, to validate the specific deficits identified in the schizophrenic population. Thirty schizophrenic patients and thirty control subjects were assessed. The data indicated that the schizophrenic subjects who showed physiological abnormalities had frontal lobe or hippocampal impairment or both. A decline in IQ with illness was found in the sub -group which showed most frontal lobe impairment. The same psychological tests were applied to schizophrenic patients' relatives (n =30). Relatives with prolonged P3 latencies showed deficits in frontal lobe and hippocampal function which were similar to those found in the patients.The third study compared the P3 amplitude and latency of visual ERPs to emotive stimuli in 15 depressed, 15 recovered depressed and 15 control subjects. The physiological data were correlated with ratings of severity of depression, depressogenic attitudes and personality variables. Significant differences were found between the depressed and control subjects in the physiological and psychological data. A significant relationship between the physiological and psychological measures was established. The study supported cognitive theories of depression by showing a negative set in information processing.The results from the three studies supported the hypothesis that P3 abnormalities reflect dysfunctions in cognitive set