Gyula Demeter

according to recent studies could be mediated by the phasic activation of locus coeruleus (LC)
(Bouret & Sara, 2005; Aston-Jones & Cohen, 2005). We know that in OCD beside the
serotonerg and dopamninerg systems (e.g., Denys, Van Der Wee, Van Megan, & Westenberg,
2003; McDougle et al., 1990) the noradrenerg system is also affected (e.g., Brambilla, Barale,
Caverzasi & Soares, 1997). It is presumed that the transmission of noradrenalin is increased
from the LC to the frontal cortex, thalamus, hypothalamus and limbic system compared to
normal subjects (Hollander et al., 1991; Brambilla et al., 1997).
There is evidence also supporting the hypo- (e.g., Chamberlain et al., 2008) respective
hyperactivity of the OFC (e.g. Rauch et al., 2007) and the hyperactivity of the anterior
cingular cortex (e.g. Maltby et al., 2005). These structures play important roles in evaluating
reward and costs and there is a growing amount of evidence that LC receives its most
prominent descending cortical projections from these frontal structures determining its
working mode (Aston-Jones & Cohen, 2005).
It can be argued that this neurobiological setting might contribute in OCD to the
overactivity of intentions and to the deficit at the cancellation component in the PM system,
determining the impaired performance in event-based PM tasks. There are a lot of open
questions and further studies are needed to clarify these hypotheses.
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