Re: Co-joined Twins and Physical/Emotional Stimuli

It is difficult to answer your questions, because "conjoined twins" (those who 
are physically connected together), can be "joined" in many different physical 
locations, and in many different ways.

For example, those who are simply physically joined at the hip or the sternum 
have completely separate nervous systems, and completely separate sets of body 
organs.  In such cases, they are two completely separate individuals, and would 
not share any physical sensations or emotions.

In order to share sensations, both twins would need to have interconnected 
central nervous system pathways.  This is extremely rare, and in most of these 
cases, not all of the CNS pathways are totally interconnected. So, even in 
these cases, the conjoined twins might be able to share some, but not all, 
physical sensations.

As for emotional reactions and sensations, these are part of the autonomic 
portion of the CNS, through the brainstem. Absent physical sensations, there 
would need to be an interconnection of the brainstem areas of the conjoined 
twins. In such a case, it would mean that the other autonomic functions, such 
as breathing, heartbeat, etc. would also be interconnected.  In most of these 
cases, one of the twins does not usually survive, and both may die quite young, 
so there is not much opportunity for researching the area of emotional 
reactions.