The Neural Basis Of Insula In Emotion Processing

Magnetic resonance imaging (MRI) has developed fast and gained widespread use for medical diagnosis and brain cognitive neuroscience in recent years. Functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) are two important techniques in the application of MR. This dissertation gave attention to the applications of fMRI and MRS in exploring the neural basis of insula underlying emotion processing. The insula is an essential and important brain region for the integration of interoceptive information (i.e. sense of the physiological state of the body) and emotional experience. In the present studiy, we focused on the neural basis of insula in emotional experience (emotion processing) and the GAB A levels in insula using fMRI and MRS. The main contents include:1. Self-processing modulates the interaction of emotional valence and arousal:the neural mechanism of insula. Emotional valence and arousal have been proved to work in an interactive way, that is conflicting approach-withdrawal tendencies (i.e., positive high-arousal and negative low-arousal words) and congruent approach-withdrawal tendencies (i.e., positive low-arousal and negative high-arousal words), and located in middle insula. The present functional magnetic resonance imaging study used participants’handwritings as material to explore how incidental self-processing affected the interaction of valence and arousal and its neural basis. Each participant was asked to read silently emotional and neutral words written by him/herself or the other person. This study focused on the neural basis of insula. Results showed that the right middle insula as well as the left putamen showed greater activations in response to emotional stimuli evoking conflicting approach-withdrawal tendencies (i.e., positive high-arousal and negative low-arousal words) relative to stimuli evoking congruent approach vs. withdrawal tendencies (i.e., positive low-arousal and negative high-arousal words), whereas a reverse activation pattern in these two regions was observed during processing other-handwriting. The current study indicated that incidental self-processing modulates the interaction of emotional valence and arousal, and the middle insula was involved in the process.2. Reputation affects one’s empathy:the neural basis of insula. Empathy enables us to understand and share the emotional and affective states of another person and plays a key role in social behaviors. Most previous studies used a paradime that asking subjects to feel others’negative emotional experience (e.g. pain). The current study investigated whether and how empathic neural responses to others’ pain were modulated by the perceived reputation of others, we focused on the activation of insula. Action histories reflecting individuals’past cooperation or betrayal actions in the repeated prisoner’s dilemma game (PDG) were introduced as an index of reputation. We assessed brain activity with functional magnetic resonance imaging (fMRI) while the participants observed individuals with a good or bad reputation receiving or not receiving pain. The results indicated that the participants exhibited reduced empathic responses in AI and dACC to the individual who had a bad reputation relative to the one who had a good reputation, suggesting that one’s empathy for pain was modulated by the perceived reputation of others, and located anterior insula.3. An MRS study of empathy and GAB A. Studies have suggested that there are individual difference in empathy. Empathy is a multidimensional construct referring to the capacity to understand and share the emotional and affective states of another person. Study on various regions of the brain have revealed links between empathy and glutamate (Glu) in humans. Cerebral y-aminobutyric acid (GABA)-ergic levels are associated with a variety of neurological and psychiatric disorders. However, the role of the GABA system in different dimensions of empathy has not been investigated. Thirty-two right-handed healthy volunteers took part in this study. We used proton magnetic resonance spectroscopy to determine GABA concentrations in the anterior insula (AI) and the anterior cingulate cortex (ACC) and to examine the relationship between the GABA concentrations and the subcomponents of empathy evaluated by the Interpersonal Reactivity Index (IRI). Pearson correlation analyses (two-tailed) showed that AI GABA was significantly associated with the empathy concern score and the personal distress score but not significantly associated with other empathy subscales. No significant correlation was found between ACC GABA and empathy subscores. Left AI GABA was positively correlated with the emotional aspects of empathy. These preliminary findings call into question whether AI GABA alterations might predict empathy dysfunction in major psychiatric disorders such as autism and schizophrenia, which have been described as deficits in emotional empathic abilities.