Self Comes to Mind

fact), and we have one mind to go with that body and one self to go with both. (Multiple selves and multiple personalities are not normal states of mind.) But the single grounding platform cannot possibly correspond to the whole body because, as a whole, the body is continuously performing different actions and changing shape accordingly, not to mention growing in size from birth to adulthood. The single platform must be found elsewhere, in a part of the body within the body, rather than in the body as a unit. It must correspond to the sectors of the body that change the least or not at all. The internal milieu and many visceral parameters associated with it provide the most invariant aspects of the organism, at any age, across a lifetime, not because they do not change but because their operations require that their condition vary only within an extremely narrow range. Bones grow across development time, and so do the muscles that move them; but the essence of the chemical bath in which life occurs—the average range of its parameters—is approximately the same whether you are three years old or fifty or eighty. Also, whether one is two feet tall or six, the biological essence of a state of fear or happiness is in all likelihood the same in terms of how such states are constructed from the chemistries in the internal milieu and the state of contraction or dilation of smooth muscles in the viscera. It is worth noting that the causes of a state of fear or happiness—the thoughts that cause those states—may be quite different across a lifetime, but the profile of one’s emotional reaction to those causes is not.
    Where does the master interoceptive system operate? The answers have become quite elaborate over the past decade thanks to work ranging from physiological recordings at the cellular level and experimental neuroanatomy studies in animals, to functional neuroimaging in humans. The upshot of this research (discussed in Chapter 4 ) is some unusually detailed knowledge about the pathways that bring such signals to the central nervous system. 7 The neural and chemical signals that describe body states enter the central nervous system at many levels of the spinal cord, the trigeminal nucleus in the brain stem, and the special collections of neurons that hover on the margin of the brain’s ventricles. From all the entry points, the signals are relayed to major integrative nuclei in the brain stem; the most important are in the nucleus tractus solitarius, the parabrachial nucleus, and the hypothalamus. From there, after being processed locally and used to regulate the life process and generate primordial feelings, they are also relayed to the sector most clearly identified with interoception, the insular cortex, after a convenient stop in the thalamic relay nuclei. Notwithstanding the significance of the cortical component of this system, I see the brain-stem component as foundational for the self process. It can provide an operational protoself as specified in the hypothesis, even when the cortical component is extensively compromised.
MASTER ORGANISM MAPS
    The master organism maps describe a schema of the entire body with its major components—head, trunk, and limb—in repose. The movements of the body are mapped against that master map. Unlike the interoceptive maps, the master organism maps change dramatically during development because they portray the musculoskeletal system and its motion. Of necessity, these maps follow increases in body size and in the range and quality of motion. They could not conceivably be the same in a toddler, an adolescent, and an adult, although some sort of temporary stability is eventually reached. As a result, the master organism maps are not the ideal source of the singularity required to constitute the protoself.
    The master interoceptive system must fit within the general framework created by the master organism schema, at every phase of the latter’s growth. A rough sketch would depict the master interoceptive system within the perimeter of the master organism framework. But the two are distinct. The fit of one system into the other does not imply an actual transfer of maps but rather a coordination such that both sets of maps can be evoked at the same time. For example, the mapping of a specific region of the body’s interior would be signaled to the sector of the master organism framework where the region best fits into the overall anatomical scheme. When we sense