The Neurophysiology of Subjectivity

Conscious experience is defined by its quality (what it feels like), but also by its subjectivity: that it feels like something to a subject. Explaining the emergence of a unified first-person perspective in the subject of experience is key to a neuroscientific understanding of subjective experience. Yet, while subjectivity has been debated by philosophers, it has often been overlooked by neuroscientific approaches to consciousness. In this chapter, we explore promising theoretical frameworks that link subjectivity to bodily signals. We introduce the neural subjective frame hypothesis, which posits that the first-person perspective is rooted in visceral signals, in particular from the heart and the stomach. These rhythmic, self-generated signals may provide a temporal scaffold that coordinates neural activity across different brain regions, facilitating the integration of disparate sensory and cognitive processes into a unified, self-centred experience. We review supporting evidence from heartbeat-evoked responses, which have been linked to self-related processes and conscious perception, demonstrating the critical role of visceral signals in shaping subjectivity. While current experimental support remains correlational, we argue that the neural subjective frame hypothesis offers promising avenues for addressing the deepest mystery in consciousness research: how neurophysiological processes give rise to subjective experience.