What kind of thing is consciousness?
Proposition
If consciousness were a thing it would have to be a perspective in that it presupposes both a reference frame or (representational) knowledge base and a singular origin or point of view. And inasmuch as it's generated by neuronal activity, consciousness would contribute to brain function by providing the perspective (or singular representation) used to coordinate the body's multiple effectors in the performance of unified (and successful) actions in the world.
Brain, body and world
We can see how this is constructed in the overall, global structure of the brain. The hindbrain manages the operational details of the body's actions, including activating groups of muscles reflexively while maintaining posture as well as operations of the internal organs and the sleep-awake cycle — all subconsciously. The midbrain aligns and stabilizes this body reference frame relative to that of the world by reconciling vestibular input with visual and auditory streams as well as with (representations of oculo-) motor output to establish a stable (world+body) reference frame with a common coordinate origin or center — albeit still subconsciously. Yet this centering (and thalamic sorting) of output and input dimensions provides the foundation for the lower forebrain to conduct the sequencing of actions (subconsciously by the basal ganglia) while the upper forebrain/cortex represents the body and its actions in the world consciously (by way of resonant neuronal activity). In other words, consciousness appears as the brain's representation of the body in the world.
Mapping the cortex
We can see this representation laid out across the cortex in terms of the components of an episode. In particular, the body itself is laid out across the top along the central sulcus with the face on the side and with output as motor actions represented by body part forward in the primary motor cortex (M1) and somatic input such as sensations of touch and proprioception rearward in the primary somatosensory cortex (S1). And where spreading somatosensory input meets the incoming stream from the primary visual cortex (V1) at the occipital pole (as well as audio from A1), the parietal cortex represents personal space as that within reach by the ("hand-eye" coordinated) spatial and motion calculations performed in this so-called WHERE pathway. (Note however that distant locations are mapped as assemblages of associations in the parahippocampal gyrus.) Forward from V1 along the so-called WHAT pathway of the temporal lobe, things and their qualities are recognized and represented, including faces in the fusiform gyrus as engaged in representing WHO. And where WHAT and WHERE pathways meet, where things are associated with complex motions, the cortex at the temperoparietal junction (TPJ) represents animacy by way of direct (subcortical) connections with the frontal cortex that represents how one would perform such actions oneself. This "HOW pathway" extends forward across the frontal cortex from the management of specific muscle actions in M1, through a hierarchy of action-operations including premotor and executive functions, and culminating with representations of overarching goals in the region of the frontal pole — which we could label WHY by including the affective influences (and motivations) of the orbitofrontal cortex (and basal forebrain) just below.
The problem
So across the cortex we see represented the WHO, WHAT, WHERE, HOW and WHY of an episode — the same components that are nightly reinforced along with sensory qualia into episodic memories by pulsations of neuronal traces in the hippocampus reactivating cortical patterns that had been coactive during the day. Yet while these various representations may well model the component dimensions of episodic consciousness, and even how memories are learned, they beg an answer to the question of how they become integrated into a singular perspective (or viewpoint in a reference frame).
The solution
This "binding problem" is resolved through the deepest layer (6) of the cortex with its connections to the claustrum — a wavy, tapered sheet of uniformly interwoven (excitatory) neurons and (inhibitory) interneurons (located between upper and lower forebrains) that resonates in synchrony with the cortex and its episodic representations of the body acting in the world. It is the singular neuronal nucleus, subnetwork and instrument that integrates resonating cortical dimensions to form the unified experiential space of conscious awareness. In fact, whereas the cortex has some thirty retinotopic maps of various aspects of the visual field, the claustrum has just one that's laid out physically (in the back corner) with the one-dimensional (1-D) coordinate lines of the visual field (e.g., azimuth and altitude) stretched onto 2-D surfaces that are physically layered into a 3-D representation of visual space — as we experience it consciously. The claustrum solves the binding problem because it instantiates a unitary network of neurons that resonates as an instrumental whole with cortical representations of the world and the body's actions in it. Also note that the principal outputs of the claustrum are projections to the caudate nucleus (at the top of the basal ganglia) that mediates voluntary control over bodily movements, to the hippocampal complex with its control over episodic memory and learning, as well as to the amygdala with its limbic functions.
Consciousness defined
With representational circuits resonating as an instrument of integration, the claustrum binds the sensory dimensions with the episodic along with actions and "feelings" into the perspectival space that forms conscious awareness. And consciousness becomes (not a thing but) the process of neuronal resonances forming the integrated perspective and representation (or "worldview") the brain uses to coordinate the body's actions in the world.
