Browsing by Subject "brain"

Aims: In earlier research it has been found that music can elicit strong emotional responses, and that mood affects the way they are processed. The brain basis of musical emotions has however been studied less than that of facial emotions. Also, there have been no studies on how depressed mood affects musical emotions in the brain. In the present study, both the effect of depressed mood state and that of depressive disorder on neural processing of musical emotions is studied. The aim is to identify brain regions affected, and to model the effective connectivity between these regions and the impact of depressed mood state and depressive disorder on this system. Methods: A functional magnetic resonance imaging (fMRI) experiment was conducted, in which 56 adult subjects listened to emotional (happy, sad, and fearful) music. The experiment consisted of two conditions: in the implicit condition the subjects were asked how many instruments were playing, and in the explicit which of the three emotions best characterised the musical excerpt. The subjects also completed the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Profile of Mood States (POMS). The behavioural and imaging data were analysed both within the general linear model (GLM) to identify affected brain regions and the dynamic causal modelling (DCM) framework to model how sensory inputs enter the brain system and how experimental conditions modulate connections between specified brain regions. Results and conclusions: The subjects were mostly not clinically depressed (76%) and the MADRS scores were not correlated with neural activity in the brain. The POMS Depression scale was however associated with attenuated activity in the right posterior cingulate cortex (PCC) while listening to happy and fearful music under the implicit condition. As PCC has been associated with internally directed cognition and the management of brain's attention networks, this attenuation is likely to reflect the incongruence between stimuli and mood state, which would result in increased attention and/or a decrease in explorative cognitive activity. Comparisons of DCM models consisting of PCC, superior temporal gyrus (STG) and the amygdala indicated that auditory stimuli enter into this system via the auditory cortex in STG. The analyses could not determine whether the emotional content of the stimuli modulates connectivity between these regions, but MADRS and POMS scores were associated with amygdala connectivity. This is in line with the view that depressive disorder disrupts the amygdala's role in orienting to affective information.

Music has an important role in our everyday lives. It is a powerful way of conveying and inducing emotions. It is even described as the language of emotions. Still, the research on the processing of musical emotions and its variations among individuals is scarce. In addition, it is not known whether the same or different neural pathways are recruited when musical emotions are processed with or without conscious awareness (i.e., implicitly or explicitly). The central aims of this thesis are 1. to examine the neural basis of the processing of musical emotions, namely happy, sad and fearful, 2. to determine the neural networks underlying the implicit and explicit processing of musical emotions and 3. to discern the effects of personality on this processing. 31 participants (mean age 27.4 years, 9 men) attended the study. Functional magnetic resonance imaging (fMRI) was used to assess the brain activation as the participants listened to musical excerpts expressing three emotions: sadness, happiness, and fear. In the implicit paradigm, participants estimated how many instruments they heard in the stimulus (one, two or many). In the explicit paradigm, participants chose the emotion that best described the stimulus (happy, sad, or fearful). Personality was evaluated using two personality questionnaires, NEO-FFI and S5. Each of the three emotions studied activated different brain regions. Processing of happy music activated the auditory cortex, processing of sad music activated the limbic and frontal areas, and processing of fearful music activated areas of the limbic system, the frontal cortex and the motor cortex. As was expected, implicit processing of musical emotions recruited both cortical and subcortical regions whereas explicit processing activated mainly cortical regions. In addition, personality traits of neuroticism, extraversion and openness affected the processing of musical emotions. Neuroticism correlated with increased activation in the temporal and frontal lobe in response to music expressing negative emotions, and in the subcortical areas in response to happy music. Extraversion correlated with decreased activation in the limbic areas in response to happy music. Openness correlated with activations in the occipital regions in response to happy and sad music. These results highlight the importance of individual differences in the processing of musical emotions and offer perspectives on the applied use of music in health care and educational settings.