What could be a physiological explanation to dissociative disorders? what are the part of the brain that are involved?

Multiple areas: Correlations have been demonstrated between the symptoms of dissociation and the right temporo parietal junction, an area involved in perspective taking, sense of self and integration of information between self and environment. There are several aspects of mental dissociation, and brain areas involved in those domains, e.g., visual/auditory/tactile processing, attention, are associated with each.