What really matters is the complex reciprocal dance in which the brain tailors its activity to a technological and sociocultural environment, which—in concert with other brains—it simultaneously alters and amends. Human intelligence owes just about everything to this looping process of mutual accommodation.
— Clark (2003, 87)
Within the self-world or system/environment loop is the brain-body loop, and within that, other loops:
The proprioceptive and interoceptive loops are closed outside the brain but inside the body. The preafferent loops are within the brain, updating the sensory cortices to expect the consequences of incipient actions.
— diagram in Freeman 2000, 222 (see also Clark 2003, 106)
These provide a preconscious form of anticipation which works faster than sensorimotor loops. The nervous system guides its body by implicitly comparing these expectations with the real consequences of action as they are sensed. In dreaming, the sensing of external reality is cut off from this loop, so the sensation of (for instance) flying is experienced as actual (Hobson 2002, 27-8). When reality checks are temporarily left out of the loop, fantasy and discovery alike find their way into the cultural universe, for some newly imagined forms later turn out to inform the external world.