Browsing by Author "Nuortimo, Antti"

Aims. Understanding of emotional processing is important for the research of mental states. A better understanding of the visual system would facilitate understanding the functioning of the entire brain. Emotions are processed in a complex neural network. The aim of the present Master's thesis is to explore the effective connectivity of the occipital face areas (OFAs) and fusiform face areas (FFAs) during the processing of visual stimuli eliciting negative emotion. Methods. The subjects (n = 16) were young adult male students. Negative and neutral emotion were elicited using visual stimuli from the International Affective Picture System (IAPS). Functional magnetic resonance imaging (fMRI) data were acquired using an MRI scanner. The fMRI data were preprocessed and analyzed using SPM8 software. In order to proceed to the psycho-physiological interaction (PPI) analyses, imaging sessions were concatenated and entered into the analyses as one single session. Subject-level model comprised the following regressors: negative emotion, neutral emotion, baseline and a binary regressor for each functional session to model session effects. An effects of interest F-contrast and a negative emotion t-contrast were defined. Spherical volumes of interest (VOIs) were computed for each subject for the left and the right occipital face area (OFA) and for the left and the right fusiform face area (FFA). The PPI variables were computed for each statistically significant VOI. A standard PPI model was defined. Each of the 4 VOIs was used as source region for all other VOIs. A group-level whole brain analysis was done for each PPI source VOI. Group-level VOI analyses were conducted for all PPI source VOIs. Results and conclusions. In the whole brain analyses statistically significant group-level PPIs were found in the following brain regions: left cuneus, right middle occipital gyrus, right and left inferior occipital gyrus, left lingual gyrus, and the left culmen. VOI analyses demonstrated the strong connectivity in the network consisting of the right OFA and left and right FFAs. Negative emotional content enhances effective connectivity in the bilateral OFA-FFA network.