OPTIMAL PERFORMANCE EXPLAINED FROM A NEUROSCIENCE POINT OF VIEW
Research suggests that there are two cognitive processes which can be examined experimentally and that are critical for top-down control and learning and may be critical for optimal performance. These two cognitive processes are: (1) feedback of an adverse outcome, which is necessary for adjusting behavioral strategies in decision-making; and (2) top-down modulation of ascending sensorimotor information to predict future states, which is an important evolutionary advantage associated with the development of complex cortical circuitry. The top-down modulatory ability is fundamentally related to the cognitive appraisal notion introduced above and to learning associations between stimuli and future pleasant or aversive outcomes. For example, the rate of reward learning depends on the discrepancy between the actual occurrence of reward and the predicted occurrence of reward, the so-called ‘reward prediction error’ (Schultz, Dayan, & Montague, 1997). Below we briefly review aspects of stress, the key neural substrates in performing under stressful conditions, and the proposed role of two brain areas that may contribute to optimal performance in extreme conditions. Neuroscientists have developed a preliminary model of optimal performance in extreme environments (Paulus et al, in press) that starts with the observation that these environments exert profound interoceptive effects. Interoception is (a) sensing the physiological condition of the body (Craig, 2002), (b) representing the internal state (Craig, 2009) within the context of ongoing activities, and (c) initiating motivated action to homeostatically regulate the internal state (Craig, 2007). Interoception includes a range of sensations such as pain (LaMotte, Thalhammer, Torebjork, & Robinson, 1982), temperature (Craig & Bushnell, 1994), itch (Schmelz, Schmidt, Bickel, Handwerker, & Torebjork, 1997), tickle (Lahuerta, Bowsher, Campbell, & Lipton, 1990), sensual touch (Vallbo, Olausson, Wessberg, & Kakuda, 1995; Olausson et al., 2002), muscle tension (Light & Perl, 2003), air hunger (Banzett et al., 2000), stomach pH (Feinle, 1998), and intestinal tension (Robinson et al., 2005), which together provide an integrated sense of the body’s physiological condition (Craig, 2002). These sensations travel via small-diameter primary afferent fibers, which eventually reach the anterior insular cortex for integration (Craig, 2003b). The interoceptive system provides this information to (1) systems that monitor value and salience (orbitofrontal cortex and amygdala); (2) are important for evaluating reward (ventral striatum/extended amygdala); and (3) are critical for cognitive control processes (anterior cingulate). Moreover, the more anterior the representation of the interoceptive state within the insular cortex the more “textured”, multimodal, and complex the information that is being processed due to the diverse cortical afferents to the mid and anterior insula. Scientists have hypothesized that the anterior insula not only receives interoceptive information but is also able to generate a predictive model (Paulus & Stein, 2006), which provides the individual with a signal of how the body will feel, similar to the “as if” loop in the Damasio somatic marker model (Damasio, 1994).
SO HOW DO OPTIMAL PERFORMERS USE THEIR BRAINS?
The interoceptive information is thus “contextualized”, i.e. brought in relation to other ongoing affective, cognitive, or experiential processes, in relation to the homeostatic state of the individual, and is used to initiate new or modify ongoing actions aimed at maintaining the individual’s homeostatic state. In this fashion interoceptive stimuli can generate an urge to act. Thus individuals who are optimal performers: (1) have developed a well “contextualized” internal body state that is associated with an appropriate level to act. In contrast, sub-optimal performers either receive interoceptive information that is too strong or too weak to adequately plan or execute appropriate actions. As a consequence, there is a mismatch between the experienced body state and the necessary action to maintain homeostasis. Therefore, a neural systems model of optimal performance in extreme environments includes brain structures that are able to process cognitive conflict and perturbation of the homeostatic balance, i.e. the anterior cingulated and insular cortex. Thus, ultimately, engagement of these brain structures is likely to be predictive of performance and may also be used as an indicator of efficacy of an intervention.
Resilience refers to (1) the ability to cope effectively with stress and adversity and (2) the positive growth following homeostatic disruption (Richardson, 2002) and is an important psychological construct to examine how individuals respond to challenging situations and stay mentally and physically healthy in the process (Tugade, Fredrickson, & Barrett, 2004c). The ability to regulate and generate positive emotions plays an important role in the development of coping strategies when confronted with a negative event (Bonanno, 2004b). In particular, resilient individuals often generate positive emotions in order to rebound from stressful encounters (Tugade, Fredrickson, & Barrett, 2004b). Nevertheless, the experimental assessment of resilience is challenging and requires novel behavioral and neural systems techniques (Charney, 2006). Despite the increasingly common and not all together correct use of the term within the military today, resilience is a complex and possibly multidimensional construct (Luthar, Cicchetti, &Becker, 2000). It includes trait variables such as temperament and personality as well as cognitive functions such as problem-solving that may work together for an individual to adequately cope with traumatic events (Campbell-Sills, Cohan, & Stein, 2006b). Here, we focus on resilience in terms of a process through which individuals successfully cope with (and bounce back from) stress (e.g., after being fired from a job, an individual adopts a proactive style improving his job hunting and work performance), rather than a simple recovery from insult (e.g., job loss causes a period of initial depressive mood followed by a return to affective baseline without attempting to modify habitual coping mechanisms to prevent its reoccurrence). The use of mental toughness training in conjunction with military physical training is based on research that aimed to show that resilience, which is a critical characteristic to perform optimally in extreme environments, has significant effects on brain structures that are thought to be important for optimal performance.
As elaborated above, neuroscientists hypothesize that limbic and paralimbic structures play an important role in helping individuals adjust to extreme conditions. Thus, the activation in amygdala and insular cortex are critically modulated by the level of resilience. In particular, if the anterior insular plays an important role in helping to predict perturbations in the internal body state, one could hypothesize that greater activation in this structure is associated with better resilience. Moreover, if one assumes that the amygdala is important in assessing salience in general and the potential of an aversive impact in particular, one could also hypothesize that greater resilience is associated with relatively less activation in the amygdala during stressful events. The involvement of the insular cortex supports our general notion that this brain structure may be critically involved in assessing ongoing internal body states as they relate to challenges in the outside world. Activation of insular cortex has been reported in a number of processes including pain (Tracey et al., 2000), interoceptive (Critchley, Wiens, Rotshtein, Ohman, & Dolan, 2004), emotion related (Phan, Wager, Taylor, & Liberzon, 2002), cognitive (Huettel, Misiurek, Jurkowski, & McCarthy, 2004), and social processes (Eisenberger, Lieberman, & Williams, 2003). In reward-related processes the insular cortex is important for subjective feeling states and interoceptive awareness (Craig, 2002; Critchley et al., 2004) and has been identified as taking part in inhibitory processing with the middle and inferior frontal gyri, frontal limbic areas, and the inferior parietal lobe (Garavan, Ross, & Stein, 1999).
WHY HOW USE A NEUSROSCIENCE APPROACH TO A BUILDING MENTAL TOUGHNESS & RESILIENCE THROUGH A MILITARY PHYSICAL TRAINING PROGRAM?
The neuroscience approach to understanding optimal performance in extreme environments has several advantages over traditional descriptive approaches. First, once the roles of specific neural substrates were identified, they could be targeted for interventions. Second, studies of specific neural substrates involved in performance in extreme environments could be used to determine what cognitive and affective processes are important for modulating optimal performance. Third, quantitative assessment of the contribution of different neural systems to performance in extreme environments could be used as indicators of training status or preparedness. The observation that the insular cortex and amygdala are modulated by levels of resilience were a first step in bringing neuroscience approaches to a better understanding of what makes individuals perform differently when exposed to extreme environments. The application of this systems neuroscience approach helps to extend findings from specific studies with individuals exposed to extreme environments to develop a more general theory. As a consequence, one can begin to develop a rational approach to develop strategies to improve performance in these environments.
SO HOW DO WE USE CSF-PREP DURING MILITARY PHYSICAL TRAINING TO INCREASE MENTAL TOUGHNESS & RESILIENCY?
Resilient individuals are able to generate positive emotions to help them cope with extreme situations (Tugade, Fredrickson, & Barrett, 2004a). According to Fredrickson’s broaden-and-build theory, positive emotions facilitate enduring personal resources and broaden one’s momentary thought of action repertoire (Fredrickson, 2004). That is, positive emotions broaden one's awareness and encourage novel, varied, and exploratory thoughts and actions which, in turn, build skills and resources. For example, experiencing a pleasant interaction with a person you asked for directions turns, over time, into a supportive friendship. Furthermore, positive emotions help resilient individuals to achieve effective coping (Werner & Smith, 1992) serving to moderate stress reactivity and mediate stress recovery (Ong, Bergeman, Bisconti, & Wallace, 2006). Neuroscientists suggest that individuals that score high on self-reported resilience may be more likely to engage the insular cortex when processing salient information and are able to generate a body prediction error that enables them to adjust more quickly to different external demand characteristics. In turn, a more adapt adjustment is thought to result in a more positive view of the world, and that this capacity helps maintain their homeostasis. This positive bias during emotion perception may provide the effective thinking strategies that resilient individuals use to interpret the world and achieve effective ways to bounce back from adversity (Bonanno, 2004a) and maintain wellness.