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Consciousness is the result of interactions among neuronal networks in our brains. Although our mechanistic understanding of consciousness remains tentative, the last two decades have seen intense and increasing efforts aimed toward elucidating the neural circuits and spatiotemporal dynamics underlying certain aspects of conscious experience. Experimental paradigms such as those involving bistable perception (wherein a constant stimulus can give rise to different percepts), combined with neurophysiological recordings and computational theories, have provided hints at neuronal signals that correlate with subjective perception. It is also revealing to determine which firing patterns do not correlate with consciousness or which ones correlate with preconscious sensations. Both nonconscious and preconscious signals have been described in perceptual studies as well as in studies of volitional decisions. Discriminating neuronal activity linked to internal perceptual changes in the absence of external changes provides empirical constraints and initial glimpses into how signaling cascades in the brain can give rise to consciousness. The phenomenological feeling of consciousness is central to our moment-to-moment experiences. What we see, hear, feel, or reminisce forms the content of conscious sensations. Most scientists would agree that consciousness is ultimately encoded and orchestrated by the activity of neurons in the brain, but the elucidation of where, when, how, and why neural ensemble dynamics lead to consciousness remains a deep and fundamental mystery. Our brains are physical entities. In many ways, the chemical components of brains are similar to those encountered in plants and trees and distinct from those in chairs and tables. An important distinguishing feature of the organization of the chemical components in our brains is the existence of interconnected neurons—yet interconnected neural circuits are also present in Caenorhabditis elegans and related worms. Whether the neuronal circuits in worms lead to conscious sensations somewhat akin to the ones experienced by humans is not clear. Out of the bewildering complexity (Tononi, 2004; Tononi & Edelman, 1998) that results from vast numbers of interconnected neurons arises the feelings of love and pain and the capacity to plan our future and prove new mathematical theorems. An elegant theoretical framework to define when, how, and why a given circuit of neurons can give rise to consciousness, whereas an apparently similar circuit or ensemble firing pattern does not has been proposed by Tononi. The theory proposes that “the level of consciousness of a physical system is related to the repertoire of causal states (information) available to the system as a whole (integration)” (2004, p. 253, emphasis in original). This theoretical framework can help distinguish why some physical systems may experience consciousness while others do not, which species can experience consciousness, why different neuronal circuits show distinct contributions to consciousness, and even why different activity patterns in the same neuronal circuit may show different correlations with conscious experience. To formulate a principled strategy to begin to investigate the problem of which aspects of brain function correlate with specific contents of conscious sensations and which do not, Crick and Koch, 1990, defined the neural correlates of consciousness (NCC). The NCC represents a “minimal set of neuronal events and mechanisms sufficient for a specific conscious percept” (Koch, 2005). Over the last two decades, growing enthusiasm and blossoming efforts have capitalized on tools to interrogate brain activity at the circuit level in order to take initial steps toward investigating the NCC. There are multiple fascinating aspects of conscious experience that need to be explained. We focus the discussion here on two of them, sensory perception and volition. With some degree of approximation, we can think of these as representative of brain input and output, respectively. We aim to provide an overview of the advances, difficulties, experiments, and theories that have shaped the discussions around the relationship between neural activity and conscious perception in a few specific instances, which we cover more thoroughly at the expense of other themes in the field. In doing so, we are not doing justice to a large body of heroic efforts. We refer the reader to several reviews (see Baars, 1989; Blanke, 2012; Blumenfeld, 2011; Cotterill, 2001; Crick, Koch, Kreiman, & Fried, 2004; PROPERTY OF MIT PRESS: FOR PROOFREADING AND INDEXING PURPOSES ONLY