IEEE Technology and Society Magazine - June 2015 - 68

now that he has been liberated from his OCD he can now
pursue a life that he would have chosen had he not been
afflicted with OCD in the first place. After all, individuals
leave their spouses for a variety of reasons. To conclude

A patient who is a candidate for a
DBS intervention may or may not be
competent (or willing) to engage
in a nuanced discussion involving
complex theory of mind issues.

that he left his wife because of his DBS would be to commit what, in logic, is called a post hoc fallacy, i.e., concluding that because one thing happens after another, the first
event caused the second event.

Core/Periphery Model
The core/periphery model of identity has previously been
proposed as a method for determining whether a significant
change to the patient's identity has been made by DBS [8].
Instead of highlighting the role of memory or the continuity
of consciousness as being the essential component of a
patient's identity, it emphasizes the role of the patient's values and priorities in determining whether a patient's identity has changed significantly. This model is based upon the
assumption that an individual's values can be represented
hierarchically and that this hierarchy is the important feature
of the individuals identity. Some values are more important
to an individual than others with the most important values

(1)

(2)

Values
Memories

Sensation

(4)
Movement

(3)
Emotion
Personality

FIgure 1. Proposed representation of the mind/identity/self
to facilitate discussions between clinicians and patients prior to
psychiatric neurosurgery.

being considered "core" values while the lesser values are
"periphery" values. Assigning values to the core and periphery is done by putting values in opposition and letting the
individual consciously endorse which he prefers.
For example, in the case of the hypothetical patient,
Steven, one can speculate that prior to surgery if he was
given the option to leave his wife and travel to a different
city he would have chosen to not do so. Therefore, one
would conclude that his role as a husband counted as
a core value to him, while the freedom of bachelorhood
would rank as a peripheral value; Steven might imagine
the thrill of freedom fondly, but he does not go beyond
fantasy and consciously endorse it with either his words
or his feet. After the DBS operation, these values appear
to have been switched. Steven no longer endorses a
desire to be a husband and father and instead prefers
to pursue the next portion of his life as an unwed man.
The core/periphery model of identity suggests that by
radically changing the elements of Steven's core values,
DBS has fundamentally altered his identity and has, thus,
interfered with his autonomy to act on his own choices.
However, this is not necessarily the case. It is equally
reasonable to suppose that prior to DBS Steven secretly
harbored resentment towards his wife because his disability made him dependent on her. Now that his disability is gone, Steven can actualize his long held but
unexpressed desire to leave his wife and start anew.
While one could argue about the quality of Steven's
character, one cannot conclude that DBS has fundamentally altered Steven. In fact, a more correct interpretation would be that DBS has liberated him to pursue his
true desires by removing the necessity of his wife's support and has, thus, increased his autonomy.
So which of these two interpretations is correct? Is
Steven's change in character a bug or a feature of DBS?

Resolution of the Models
The three presented models of identity are meant to highlight the relative nature of the hypothetical case and how
this nature leads to ambiguous interpretations. However,
while the case is ambiguous in a general sense, there is
actually a specific truth for this specific patient, Steven.
There is a critical, but missing clue that cinches whether
this alteration to the patient's personality is a good, bad,
or unimportant result of DBS. That clue is Steven's perception of his identity. The necessary information missing in
the discussions of risks and benefits of surgery during the
informed consent procedure was an explicit understanding of how Steven viewed himself and what elements of
that self he was willing or unwilling to alter as a result of
surgery. While we do know for certain that he wished to
eliminate the sensations and behaviors associated with
his OCD, we do not have the same knowledge about
the remainder of his mind. The three models of identity

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june 2015

Table of Contents for the Digital Edition of IEEE Technology and Society Magazine - June 2015