حضور ذهن در مقابل نشخوار و بازداری رفتاری: چشم انداز تحقیقات در مورد عدم تقارن فرونتال مغزی

Mindfulness represents an attribute of consciousness involving an intentional focus on the present-moment experience with a non-judgmental attitude. Due to this quality, it attenuates rumination, a maladaptive way of coping with negative mood characterized by a continuous, passive focus on particularly negative emotions. Only few studies have examined mindfulness and rumination in relation to basic notions of human motivation, such as the behavioral inhibition and activation systems (BIS/BAS), and the approach–withdrawal model of hemispheric asymmetry. We examined the indicated parameters and frontal brain asymmetry, assessed through the alpha band (8–13 Hz) in resting-state electroencephalogram. Alpha asymmetry represents a neurophysiologic marker of approach vs. withdrawal-related response dispositions. In line with previous findings, trait mindfulness and rumination were negatively related to each other. Further, rumination was positively and mindfulness negatively related to BIS, while neither parameter showed a consistent association with BAS. Frontal alpha asymmetry on the other hand was significantly associated with BAS, but not with BIS. Hence, rumination appears to be characterized by behavioral inhibition, but not by dispositions of active withdrawal. Mindfulness on the other hand is related to lower behavioral inhibition, but is not necessarily associated with behavioral activation or approach dispositions.

Mindfulness represents an attribute of consciousness involving an intentional, active focus on the present-moment experience with a non-judgmental attitude (Brown & Ryan, 2003). As a trait, it is related to various parameters of psychological well-being, including higher optimism, life satisfaction and vitality, as well as lower rumination, anxiety and depression (Brown and Ryan, 2003 and Keune et al., 2011). Bishop et al. (2004) proposed an integrative model to describe the working mechanisms of mindfulness. According to this model, mindfulness involves two basic components. The first component is the self-regulation of attention in a way that keeps attention focused on the present experience. This is assumed to yield sustained attention and to inhibit further elaboration upon sensations, cognitions and emotions. The second component is an orientation toward experience which is accepting, open and curious. The suggested consequence is a reduction of avoidant behavior patterns and increased affect tolerance. In the context of contemporary theories of personality psychology, it has been suggested that the state of open awareness which characterizes mindfulness can be seen as essential in promoting choices of behavior which are congruent with personal needs and values (Brown and Ryan, 2003, Brown et al., 2007 and Keune and Perczel-Forintos, 2010). Rumination represents a process running contrary to mindfulness. It involves a passive focus on specifically negative emotions (Nolen-Hoeksema, Wisco, & Lyubomirsky, 2008), is associated with numerous maladaptive characteristics such as dysfunctional attitudes, hopelessness and neuroticism, and represents a vulnerability factor for depression (Lam et al., 2003 and Smith et al., 2006). Mindfulness appears to counteract these characteristics. It has been shown that mindfulness training enhances trait mindfulness and attenuates rumination, suggesting that the two are negatively associated in a dynamic fashion (Keune et al., 2011, Kingston et al., 2007 and Ramel et al., 2004). Moreover, particularly the non-judgmental component, as suggested by Bishop et al. (2004), appears to be relevant for the negative relation between mindfulness and rumination (Evans & Segerstrom, 2010). To date, only few studies have examined mindfulness and rumination in the context of basic theories of human motivation (Sauer, Walach, & Kohls, 2011). In the reinforcement sensitivity theory, Gray and colleagues (Gray, 1982 and Gray and McNaughton, 1996) proposed a model according to which two fundamental systems guide behavior. The behavioral activation system (BAS) drives individuals towards positive and negative reinforcement. As such, it mediates approach behavior and active avoidance, and is supposed to be related to greater general positive affectivity (Gable et al., 2000 and Gray and McNaughton, 1996). The behavioral inhibition system (BIS) on the other hand implies sensitivity to signals of punishment and nonreward. This system is assumed to mediate passive avoidance, and to be associated with greater general negative affectivity (Gable et al., 2000). Davidson, Ekman, Saron, Senulis, and Friesen (1990) suggested two dimensions of approach and withdrawal, which are partly reflected by tonic left and right frontal cortical brain activity. Individuals characterized by approach-related behavioral dispositions are assumed to display stronger relative left-hemispheric anterior cortical activity, whereas individuals characterized by withdrawal show stronger relative right-hemispheric anterior cortical activity (Allen et al., 2004 and Keune et al., 2011). Power in the alpha band (8–13 Hz) in resting-state electroencephalogram (EEG) is frequently used as an indicator of asymmetry based on the rationale that alpha power is inversely related to underlying cortical activity (Allen et al., 2004). It has been shown that 60% of the variance of the alpha asymmetry phenotype derived from resting-state assessments reflects trait components, whereas 40% can be attributed to state influences (Hagemann, Hewig, Seifert, Naumann, & Bartussek, 2005). While early studies regarded approach and withdrawal as congruent with BAS and BIS (Sutton & Davidson, 1997), respectively, the contemporarily prevailing view is that both, approach and withdrawal systems, are rather subsystems of the BAS (Coan and Allen, 2003 and Hewig et al., 2004). This is plausible since the BAS does not only mediate approach tendencies, but also realizes active avoidance driven through negative reinforcement. Recently, the capability model of EEG alpha asymmetry has been suggested as an extension of the classic approach-withdrawal model (Coan, Allen, & McKnight, 2006). This model extends the notion of alpha asymmetry as a static indicator of response dispositions, by considering the interaction of emotional demands and the capability to regulate emotions during challenging situations. Individual differences in alpha asymmetry during emotional challenges are assumed to be more reliable and more strongly associated with relevant criterion variables than during neutral resting-conditions. Several studies have provided support for the capability model (Keune et al., 2011, Steiner and Coan, 2011 and Stewart et al., 2011). The purpose of the current study was to examine the relation of trait mindfulness and rumination to notions of BIS/BAS and the approach-withdrawal model. To this aim, healthy participants completed relevant trait self-report measures and two resting-state EEG assessments, one during a neutral condition, and a second one following the induction of a sad mood. The latter condition was included in relation to the capability model of EEG alpha asymmetry (Coan et al., 2006). Several hypotheses can be derived from the characteristics of mindfulness and rumination as described above. Firstly, since rumination represents a passive approach to coping with negative emotions and is related to negative affectivity, it can be assumed to be associated with higher behavioral inhibition, i.e. higher BIS scores. Complementarily, it may also be related to lower BAS scores. Since mindfulness is inversely related to rumination, the respective opposite relations to BIS/BAS can be expected for mindfulness. At this stage, depending on the observed pattern of associations between rumination, mindfulness and BIS/BAS, further assumptions can be derived: If mindfulness and rumination are related to BAS, they may also be expected to be associated with alpha asymmetry, as the approach and withdrawal systems are subcomponents of the BAS. For mindfulness an association with stronger relative left-hemispheric anterior cortical activity, indicative of approach could be expected. In case of rumination, a pattern indicative of withdrawal would be likely. If these associations are observed, they may be assumed to be particularly pronounced for alpha asymmetry scores derived from a negative mood condition, according to the capability model of EEG alpha asymmetry. Alternatively, if mindfulness and rumination are only associated with BIS, no association with alpha asymmetry can be expected, as the approach and withdrawal systems represent subcomponents of the BAS only. With regard to both possibilities, a secondary hypothesis refers to the replication of previous findings, according to which BAS but not BIS scores are related to frontal alpha asymmetry.

The current study is the first to concurrently assess trait mindfulness and rumination, as well as parameters of BIS/BAS and neural correlates of approach vs. withdrawal. The current results allow the suggestion that trait mindfulness and rumination relate systematically to BIS, but not to BAS, and in line with this observation are not directly associated with approach vs. withdrawal-related response dispositions.