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Investigating Differences in the Default Mode Network in Empathy Related StimuliAuthor: Shubhangi Gautam Date: 2021-09-11 Report no: IIIT/TH/2021/95 Advisor:Kavita Vemuri AbstractEmpathy, a complex social skill, allows for the ability to understand the emotional and cognitive states of another. In general, empathy is crucial in the social world and for survival. Several studies have demonstrated that the default mode network (DMN) is involved in the process of internal mental simulations (also known as mind wandering) - an aspect significant for empathetic response. Researchers have found an overlap in brain regions between the social networks and the DMN. Since the DMN is activated during the mind wandering process, most of empathy literature has examined the DMN during resting state. Therefore in this thesis, we investigate the functional connectivity differences in resting state DMN and empathy-task DMN. In this study, we apply a novel time-frequency filter method on the BOLD signal to investigate the FC of the DMN. The aim of this thesis is to demonstrate the role of the DMN in empathetic processes and to further identify the time-frequency characteristics of the DMN activations during free-viewing emotional movie clips. Specifically, we use movie clips because research has shown more intense emotions being evoked in participants during dynamic stimuli vs static stimuli. And since we want to capture the complex psychological process of empathy, we decided to use emotional movie clips to portray the naturalistic complexity of human interactions. It must be noted that the time-frequency technique used in this thesis (the single frequency filter bank) provides a better resolution compared to traditional approaches such as sliding window. Using this novel technique, analysis on two sets of fMRI data were conducted to examine the time-frequency dynamics. To the best of our knowledge, this is the first study to explore the time-frequency characteristics of the DMN in empathy tasks. In the first experiment, fMRI response signals from the three short diverse movie clips (Disney, Green, and Taare) were analyzed. Before the stimuli was presented, resting state data of 3 minutes was also recorded for the 8 participants. Specific scans which consisted of the most emotional scenes were chosen to conduct the comparative analysis. The results from this preliminary investigation demonstrated differences in the activations between empathetic task vs resting state. This preliminary study corroborates findings from previous studies. For example, we found highly skewed power distributions where most power was at the lowest frequencies. This has been shown in previous research as well Full thesis: pdf Centre for Others |
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