The Conscious Brain

The goal of this article is to review some aspects of brain anatomy and neurophysiology that are important for consciousness, and which hopefully may be of benefit to philosophers investigating the conscious mind. Taking as an initial point of reference the distinction between “the hard problem” and “the weak problems” of consciousness, we shall concentrate on questions pertaining to the second of these. A putative “consciousness system” in the brain will be presented, paying special attention to diffuse projection systems. The “center of gravity” will be brain connectivity, since consciousness must, critically, be dependent on coherent activity and timing. “Detectors” of synchronicity and coincidence, like NMDA receptors, also necessarily play a role here. To be conscious, we do not need an entire brain. While even large hemispherectomies need not unequivocally affect consciousness, far smaller brain-stem lesions may be devastating in this regard. Even so, the recent discovery by Matthew F. Glasser et al. of 180 separate areas in the human brain cortex is intriguing from a teleological perspective, as it is quite unthinkable that any of them could be “redundant.