How the Brain Processes Emotional Arousal via the Interoception of the Diaphragm

Abstract

Summary The hypothesis that the brain is a networked prediction machine for the body’s external and internal states, in which predictions are updated according to perdition errors, states that it generates emotion using the five senses and interoception (sense of the body’s inner state) during visceromotor control. Although we know that, for instance, respiration and emotion are correlated, how respiration works in this hypothesis remains unclear. Respiration is produced by mechanical diaphragm movements. Electrical activity of the diaphragm (EAdi) is the input signal for the electromechanical diaphragmatic control as used for driving of mechanical ventilation devices. Attachment of a negative electrical impedance to EAdi electrodes dramatically amplifies and attenuates biological-origin EAdi (called percutaneous extracellular impedance control: pEIC), generating prediction errors in the electromechanical control of the diaphragm. pEIC, moreover, never produces any somatic perception that would affect emotion. We performed an intuitive high-or-low emotional valence judgement task using images with high-or-low valence and arousal scores with and without pEIC. Although the task was imposed on stimulus valence, the reaction time and hit rate significantly differed between the high and low arousal conditions without pEIC, with them being significantly modulated by the pEIC. These phenomena occurred in both current and previous trials, which is relevant to short-term arousal prediction (or generation) and its update in the hypothesis, respectively. A high-or-low arousal and the use of pEIC had significant effects on the electroencephalogram amplitude and that of the EAdi phase, respectively. Therefore, the brain does predict emotional arousal via interoception of the diaphragm.

Funding Information: This project was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI Grant (18H03500 and 22K18417) and Japan Science and Technology Agency (JST) COI (JPMJCE1311

Declaration of Interests: The authors declare no competing interests.

Ethics Approval Statement: The participants gave written informed consent after they were given a detailed explanation of this study. The study was done in accordance with the Declaration of Helsinki and was approved by the Ethical Committee for Epidemiology of Hiroshima University #E-2158.

Keywords: emotion, valence, arousal, interoception, respiration, Diaphragm, predictive coding, electrical intervention