Neural Mechanisms as Putative Targets for Warfighter Resilience and Optimal Performance - Neurotechnology in National Security and Defense - page 52

anxiety, and posttraumatic stress disorder (PTSD; Spencer et al. 2010). Moreover,
longitudinal work is required to examine the trajectory of performance changes and
recovery (Vasterling et al. 2009).
There is some evidence that military deployment may compromise performance
on tasks of sustained attention, verbal learning, and visual-spatial memory, whereas
it enhances performance on simple reaction time (Vasterling et al. 2006). Others
have found that following acute stress of combat simulation, soldiers showed a shift
in attention away from threat (Wald et al. 2010). The assessment of neurocogni-
tive performances is particularly important because there is evidence suggesting that
performance decrements are associated with the development of postdeployment
PTSD symptoms (Marx et al. 2009), which is consistent with the idea that domains
of cognitive function may serve as risk or protective factors for PTSD (Gilbertson et
al. 2006). The effect of combat exposure on brain function is still very much under
study. While some have suggested that no consistent findings have emerged across
advanced brain imaging techniques (Zhang et al. 2010). More recently, there is con-
verging evidence to suggest involvement of the frontal and limbic systems. Using
both electroencephalography (EEG) and (structural) magnetic resonance imag-
ing (MRI), alteration of EEG phase synchrony was associated with the changes in
structural integrity of white matter tracts of the frontal lobe (Sponheim et al. 2011).
Moreover, there is evidence that combat stress increases amygdala and insula reac-
tivity to biologically salient stimuli, which has been taken as evidence that threat
appraisal affects interoceptive awareness and amygdala regulation (van Wingen et
al. 2011). Research has also found that combat exposure affects the balance between
activation in ventral frontolimbic regions, which are important for processing emo-
tional information, and dorsolateral prefrontal regions, which are important for
executive functioning (Morey et al. 2008). Additionally, increased activation to
combat-related stimuli has been reported in the visual cortex (Hendler et al. 2003).
Taken together, these and other studies show that cognitive and brain function is
significantly affected by deployment. However, what is much less clear is how cogni-
tive and brain function recovers as soldiers return home from combat deployment.
RESILIENCE
Resilience is a complex and possibly multidimensional construct (Davidson 2000).
It includes trait variables such as temperament and personality, as well as cogni-
tive functions such as problem solving that may work together for an individual to
adequately cope with traumatic events (Campbell-Sills et al. 2006). Here, we focus
on resilience in terms of a process through which individuals successfully cope with
(and bounce back from) stress. For instance, after being fired from a job, a resilient
individual adopts a proactive style in improving his job hunting and work perfor-
mance. In contrast, a less resilient individual may adopt a simple recovery from
insult where job loss causes a period of initial depressive mood followed by a return
to affective baseline without an attempt to modify habitual coping mechanisms.
Further studies are needed to show that resilience, which is a critical characteristic of
optimal performance in extreme environments, has significant effects on brain struc-
tures that are thought to be important for such performance. Our approach has been