Persistent CNS viral infections could alter production of transmitters and receptors as well as cellular mechanisms. The summation of causes 1-3 results in an impaired flexibility of the brain to alter the function of its neural networks to deal with changing internal or external circumstances. An example of this deficit may be encountered in the well-known problem that many neurosomatic patients have in making new memories. In order to encode a memory, a fragile neural network must be strengthened. NO diffuses in a paracrine manner into firing neurons in the locality, enhancing glutamate secretion.
Neurosomatic patients have an impairment in neural plasticity.
Deficiency in the neurobiology of encoding is one example of this pervasive disorder. Thus the individual who is predisposed to develop a neurosomatic disorder may have neural network function dysregulated by overtaxing his capacity for neural plasticity. Humans, like animals in whom these experiments have been done more rigorously, respond to medication almost idiosyncratically, since everyone's brain is different. The same pill can make one patient alert and pain-free, have no effect in a second, and exacerbate all the symptoms of a third. I have demonstrated these immediate results of treatment on cerebral blood flow in Betrayal by the Brain.