Self Comes to Mind

look.
    What might account for the last turn of events in Alzheimer’s disease? A definite answer is not possible because, along the years of disease, there are several sites of pathology in the Alzheimer brain and the pathology is not confined to neurofibrillary tangles. But to some extent the damage remains selective. The image-making sections of the brain, namely, the early sensory cortices of vision and hearing, are not burdened by disease, nor are the movement-related regions in the cerebral cortex, the basal ganglia, and the cerebellum. On the other hand, some of the regions related to life regulation, on which the protoself depends, are progressively damaged. They include not just the insular cortex but also the parabrachial nucleus, something our group was also able to establish. 12 Finally, other brain sectors rich in CDRegions show severe damage. The PMCs figure prominently among the last.

     
Figure 9.6: The top panel shows the medial view of the left cerebral hemisphere in a normal older individual. The PMC region is shaded. The bottom panel shows the same view in an individual of approximately the same age who had advanced Alzheimer’s disease. The shaded PMC region is severely atrophic.
    The reason I am paying special attention to these facts is that early in the disease the PMCs show mostly neuritic plaques, but late in the disease the pathology is dominated by deposition of neurofibrillary tangles, the tombstones of former healthy neurons to which I alluded earlier. Their massive presence in the PMCs suggests that the operation of the region is severely compromised. 13
    We had been quite aware of important pathological changes in the PMCs, to which, in those days, we simply referred as the “posterior cingulate cortex and surround.” But the repeated clinical observation of impaired consciousness in late-stage Alzheimer’s, in cases of focal damage to this region, and its peculiar anatomical placement made me wonder if severely damaged PMCs might be the drop that made the cup overflow. 14
    Why is this region a target of Alzheimer’s pathology? The reason may well be the same one my colleagues and I invoked, many years ago, to account for the prevalent pathological involvements of the medial temporal lobe regions in the same disease. 15 In normal health the entorhinal cortex and the hippocampus never cease their operations. They work day and night to assist with the processing of factual memories by initiating and consolidating memory records. Accordingly, local cellular toxicity associated with major wear and tear would take their toll on the region’s precious neurons. Much the same reasoning would apply to the PMCs, given their nearly continuous operation in a variety of self-related processes. 16
    In sum, patients in late-stage Alzheimer’s disease with evident compromises of consciousness have disproportionate neuronal damage and thus dysfunction of two brain territories whose integrity is necessary for normal consciousness: the PMCs and the brain-stem tegmentum. One should be prudent regarding the interpretation of these facts, given that there are other sites of dysfunction in Alzheimer’s disease. At the same time it would be foolish not to consider this evidence.
    And what about the patients themselves, who at this late stage in the disease receive yet another blow to the health of their brains? In the past my view has been, and still is today, that much as the new insult is painful to watch by those who are close to the victims, it is probably a blessing in disguise for the patient. Patients in this late stage and with this degree of impaired consciousness cannot possibly be aware of the ravages of the disease. They are shells of the human beings they once were, deserving of our love and care to the bitter end but now thankfully freed, to some degree, of the laws of pain and suffering that still apply to those who watch them.
COMA, VEGETATIVE STATE, AND THE CONTRAST
TO LOCKED-IN SYNDROME
    Patients in coma are largely unresponsive to communication from the outside world, deep in a sleep in which even the pattern of breathing often sounds abnormal. They do not make meaningful gestures or utter meaningful sounds, let alone use words. None of the critical components of consciousness that I listed in Chapter 8 is in evidence. wakefulness is gone for certain; and, based on the observable behavior, mind and self are reasonably presumed to be absent.
    Patients in coma often have damage to