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The Ernst triadic model

Brain and Cognition xxx (2014) xxx–xxx
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Brain and Cognition
journal homepage: www.elsevier.com/locate/b&c
The Ernst triadic model: A good start?
Howard Sercombe
University of Strathclyde, 6th Floor, Lord Hope Building, 141 St James Road, Glasgow G4 0LT, United Kingdom
As a sociologist and youth worker, I have been interested for
some years in the contribution of neuroscience to a number of social
phenomena, and to the expanding interface between social science
and neuroscience (and other disciplines within the new generation
of biological sciences, such as epigenetics). The dialogue with clinical youth work practice and with sociology, rather than psychology,
sometimes involves quite different insights and perspectives. For
example, neuroscience can itself be seen as a cultural product, in
its epistemological assumptions, and in the production of neuroscientific narratives about the nature of human experience.
One such narrative is about how risk-taking among young people relates to brain function. While many young people are not particularly adventurous (Payne, 2012), adolescence has become
associated with ‘typical impulsive/risky behaviours’ (Ernst, 2013).
The neuroscientific basis of this tendency is thought to lie in the
heightened responsiveness of reward circuitry in the brain in the
teenage years, combined with regulatory circuits which are yet
to establish their full capacity.
A core point to this narrative is Ernst’s suggestion that avoidance mechanisms, as well as reward mechanisms and executive
control functions, are likely to be implicated in decision-making
about risk. She posits a triadic model, in which the prefrontal cortex (PFC), the striatum and amygdala are all likely involved in a
reciprocal relationship in such operations.
From the position of a non-neuroscientist, this model has much
to commend it. First, it takes us beyond a simple bilateral reward/
control dynamic involving only (or even principally) the striatum/
nucleus accumbens (Nacc) and the PFC. While interesting and
potentially productive, the theory that risk taking among young
people was predominantly down to the Nacc/PFC nexus quickly
gained a currency and certainty that seemed to overreach the evidence for a number of reasons.
First, risk taking among adolescents is far from universal, while
presumably the Nacc/PFC disconnect is. This has not been sufficiently addressed in typical caveats in the literature about individual variation. If the teenage brain is biologically predisposed to
taking risks, the relative absence of risk-taking behaviour among
most young people most of the time needs to be explained. On the
issues most frequently cited as typical of adolescent risk taking,
for example, 60% of adolescents in a recent study used condoms
the last time they had sex, which is generally better than other
adults’ rates of condom use (Anderson, Wilson, Doll, Jones, &
Barker, 1999), and around 90% of young women reported that they
did not have multiple sexual partners (Morrison-Beedy et al., 2012).
In the 2007 National Drug Use Survey, 90% of 12-17 year olds had
not used illegal drugs in the last month (Aldworth, 2009: 20), compared with 95% of people in their 50s (Aldworth, 2009: 22). The drug
use rate for 18-25 year olds was higher, but still, 80% had not used
illegal drugs in the last month (Aldworth, 2009: 21).
Methodologically, the reward/regulatory model brings together
a discovery about the differential response levels of adolescence
and evidence of the slower developmental trajectory of the PFC
with a powerful cultural script about the recklessness of youth,
making a logical leap that is not unreasonable, but much more certain in its prescriptions than the evidence supports. In the process,
it hooked into deficit models of youth as pathology that have dominated our perspectives on young people for the last century. The
Nacc/PFC nexus cannot be an adequate explanation of adolescent
risk-taking behaviour in the face of the empirical reality that most
young people don’t take a lot of risk.
Second, risk-taking is complex behaviour. It seems unlikely that
deciding to race the car next to you along a public highway, accept a
powerful psychotropic drug of unknown origin from a stranger in a
club, or even follow up eye contact with that colleague at a conference is down to a simple two-way tug of war between reward seeking and regulatory function. It seems probable that decisions like
this would involve a whole range of brain regions in a complex flurry
of business involving apprehension of the likely consequences, responses to what others around you (and others later) might think
of you, concern for your image and reputation and therefore social
identity, dialogue with ethical, religious and ideological superstructures, memories of previous opportunities missed or taken up. In
this flurry of activity, no doubt the Nacc and PFC are involved, but
it seems less obvious that the interplay of reward seeking and regulatory function is the determinant or even necessarily dominant
process. At least, one would think, elements of the ‘social brain’ like
the superior temporal sulcus (Blakemore, 2008) must be involved in
the process.
Monique Ernst’s contribution adds significantly to the Nacc/PFC
dyad on two levels. On a common sense view, the triadic model, in
incorporating fear/aversion processes into the narrative about risk
taking behaviour, is likely to approximate actual behaviour more
closely than the dyadic hypothesis. If there is nothing to be
frightened of, if there is no downside to a decision, it is not a
risk-taking event. At minimum, one would expect the amygdala
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Please cite this article in press as: Sercombe, H. The Ernst triadic model: A good start? Brain and Cognition (2014), http://dx.doi.org/10.1016/
H. Sercombe / Brain and Cognition xxx (2014) xxx–xxx
to be part of the equation, and it would seem sensible for researchers to begin exploring that relationship.
But Ernst’s approach also opens up a different methodological
approach. The narrative about the Nacc/PFC nexus and adolescent
risk taking behaviour took indicative conclusions about the nature
of brain development in teenagers, and matched them with the
dominant consensus about adolescent behaviour and risk taking.
Ernst’s approach reads in the opposite direction: dissecting human
behaviour, then looking for the way that the brain might work as a
system in the production of particular kinds of human action. As
the neuroscience moves further in the direction of understanding
networks within the brain and communication between regions
rather than specific functions of specific regions, this approach
may prove to be fruitful.
Aldworth, J. (2009). Results from the 2007 national survey on drug use and health:
National findings. Rockville: DIANE Publishing.
Anderson, J. E., Wilson, R., Doll, L., Jones, T. S., & Barker, P. (1999). Condom use and
HIV risk behaviors among US adults: Data from a national survey. Family
Planning Perspectives, 31(1), 24–28.
Blakemore, S.-J. (2008). The social brain in adolescence. Nature Reviews
Neuroscience, 9(4), 267–277.
Morrison-Beedy, D., Jones, S. H., Xia, Y., Tu, X., Crean, H. F., & Carey, M. P. (2012).
Reducing sexual risk behavior in adolescent girls: Results from a randomized
controlled trial. Journal of Adolescent Health, 52, 314–321.
Payne, M. A. (2012). All gas and no brakes! Journal of Adolescent Research, 27(1),
Please cite this article in press as: Sercombe, H. The Ernst triadic model: A good start? Brain and Cognition (2014), http://dx.doi.org/10.1016/