Subjective Experience and Its Neural Basis

Abstract

This chapter reviews current perspectives on the neural basis of subjective experience. Its primary focus is on the interaction between two broad dimensions of experience: subjective contents (e.g., the conscious experience of seeing a red ball or feeling a sharp pain) and the global brain states that modulate the representation of those contents and how they evolve over time (e.g., moods, dreaming, and vigilance). The neural basis of these two aspects of experience will be discussed across multiple levels of description, including large-scale network, neurocomputational, and cellular-level perspectives. When integrated, these perspectives highlight the way that small-scale neuronal circuits may be interconnected so as to implement a hierarchical computational system for inferring the probability that various states of the world (including the body), at various levels of description, have caused the sensory input that has been received. Emotional experience is used to provide an in-depth example of the complex interactions within this type of system that are necessary to account for this phenomenon. The chapter next turns to the role of global brain states in modulating the contents of experience – including mood, sleep/dreaming, and other altered states of consciousness. Global brain states are linked to the broad influence of neuromodulators and the way they can alter neurocomputational inference processes by either amplifying or attenuating the relative influence of prior expectations and sensory input on experience. Different global brain states are then associated with different patterns of modulatory influence on neuronal populations encoding different types of prior expectations at different levels of hierarchical processing. This chapter also briefly considers the potential clinical relevance of understanding the neural basis of what contents do and do not become consciously accessible, and the vulnerabilities of such a system for transitioning into maladaptive states. This chapter ends by highlighting the nascent state of the field of consciousness research and the importance of an interdisciplinary, multilevel approach to understanding this important topic.