Typically, the organs of the body have distinct borders, often with their own endometrial or core sheathing.
What is proposed here is that there already exists a de facto notion of a virtual central nervous system organ, and instead, this will formalize both the definiton, clarify the past non - obvious use of the concept, and define how the delineation of such organs as a class can be pursued with better certainty.
The simplest way to view an organ is as a part of a living being that has a specific global purpose.
For psychiatrists, examples of de facto CNS organs include the model of Freud (the Id, the Ego, and the Super Id.). We are hard pressed to find where these reside in the body and the brain.
Cranial nerves are well defined and can be easily located -- the same is true of structures in the pituitary and the hypothalamus.
But we cannot find organs within the limbic structures and executive and cognitive structurs of the brain, for the simple reason that the same portions of the brain serve multiple purposes.
The concept of a virtual CNS organ becomes compelling particulalry in the setting of our understanding of psychiatric illness.
In psychiatric illness, certain concepts are central to our description of illlness, but we do not find a structure that plays a role unique and exclusive to that task.
In affective illness, we know that there is a specific way in which the brain is unable to maintain affect. For this reason, as the antecedents and the conseuqences may be varied, but the organization of those antecedents and conseuqneces is reporducible in minute features. This makes possible the categorization of disease that is in many ways distinguishable between cases only by individual variation.
An example: one patient with anhedonia may find they no longer enjoy a hobby -- another patient, that they no longer enjoy work. Different patients, different presentations, but the same biological phenomena, and, if we accept the notion of a virtual CNS organ, innvolving the same organ, perhaps even in the same pathologic process.
If we then posit that there is a quite distinct pathologic phenomena, but that it is having an effect on the same organ, we then say -- we have correctly linked a virtual CNS organ with the affective diseases (in some measure).