The neurobiological mechanisms associated with affiliation,
that Depue & Collins argue are a central component of extraversion
are not specified in their model. In addition, only the involvement of
the prefrontal cortex in extraversion is discussed, although recent
evidence suggests that activity associated with additional cortical
regions may be related to this trait. Finally, the assumption that
neurobiological mechanisms underlie or play a causal, and therefore,
more fundamental role than psychological constructs in the trait is
challenged.