br Emotion regulation the adolescent brain

Emotion regulation, the adolescent RVX-208 and adolescent psychopathology
Conclusions The development of emotion regulation during adolescence has enjoyed a recent surge in interest, largely prompted by discoveries over the past 15 years or so regarding ongoing adolescent development of the cortical and subcortical circuitry underpinning regulatory processes. This review brings together models concerning the structural and functional development of the adolescent brain with models of emotion regulatory processes. It is likely that development continues to occur in processes underpinning all three stages of the extended process model, namely Identification, Selection and Implementation. However, the majority of behavioural and neuroimaging work to date has focused on Implementation. There is some evidence that both behavioural and neural responses during implicit emotion regulation tasks such as emotional go/no-go task variants develop in a non-linear manner, with mid-adolescents showing exaggerated responses to emotion compared with younger and older individuals. This would support models suggesting that non-linear structural brain development has consequences for brain function and adolescent behaviour. However, not all studies show this pattern, and it is unlikely that links between brain structure, brain function and behaviour will be straightforward. For example, even if brain and behaviour are shown to follow similar developmental trajectories for a given function, this does not necessarily mean that one trajectory causes the other (Pfeifer and Allen, 2012). Regarding explicit strategies such as reappraisal, some studies show an increase in the use of this strategy over adolescence, in line with theories suggesting that reappraisal use should increase as underlying executive, verbal and social cognitive skills develop. However, others suggest that instructed use may not be paralleled by increasing spontaneous use with age in everyday life. As there are still relatively few studies in the area, methodological differences across studies make it difficult to draw overall conclusions. These include whether emotion is relevant or irrelevant to task performance, whether particular strategies are instructed or not, how tasks are adapted for neuroimaging, and sample age range and size. As more empirical work becomes available, an important next step will be to synthesise evidence through the use of meta-analysis. Some outstanding research questions are listed in Box 2. Of most practical relevance will be work delineating relationships between the neural bases of emotion regulation and the emergence and prevention of psychopathological symptoms. The plasticity of the adolescent brain at this time could yield opportunities for positive intervention before symptoms escalate to clinical levels.
Acknowledgments This work was supported by an Economic and Social Research Council award to C.L.S. (ES/K008951/1) and a PhD Crossland Scholarship from Royal Holloway University of London awarded to S.P.A.
Introduction Ever since the discovery of motor neurons that are activated during the observation of others’ actions in both monkeys (Gallese et al., 1996) and humans (Fadiga et al., 1995; Mukamel et al., 2010), there has been a renewed interest in the idea that observing, imagining, or in any way representing an action, activates the motor programmes that are typically used to execute that same action (James, 1890; Jeannerod, 1994; Prinz, 1997; Stock and Stock, 2004). Infants’ limited, yet developing motor repertoire has the potential to shed light on the development of this phenomenon, and in recent years many researchers have investigated the relationship between action execution and action observation in infancy (e.g. Longo and Bertenthal, 2006; Sommerville et al., 2005; van Elk et al., 2008; Virji-Babul et al., 2012; Von Hofsten, 2007). Many of these studies have investigated the shared neural activation during action execution and observation by measuring alpha suppression over the sensorimotor areas using electroencephalography (EEG) (Marshall et al., 2011; Southgate et al., 2009, 2010; van Elk et al., 2008; Virji-Babul et al., 2012). While at rest, sensorimotor neurons fire spontaneously in synchrony leading to large amplitude EEG oscillations in the alpha frequency band (8–13Hz in adults and 6–9Hz in infants) (Pineda, 2005; Stroganova et al., 1999). Whenever the sensorimotor cortex is activated, i.e. during the execution and observation of actions, the firing of the neurons becomes desynchronized leading to a decrease in power of the sensorimotor alpha-band oscillations (Pfurtscheller and Neuper, 1997; Salmelin and Hari, 1994). The sensorimotor alpha rhythm is distinct from the visual alpha rhythm at posterior sites (Stroganova et al., 1999), and is attenuated in response to both the observation and execution of actions from at least 9 months of age (Marshall et al., 2011; Southgate et al., 2009, 2010). Source localisation analyses of MEG data suggest that the sensorimotor alpha rhythm most likely originates in the somatosensory cortex (Hari and Salmelin, 1997; Salmelin et al., 1995), which has been shown to have mirroring properties (Gazzola and Keysers, 2009) but is not typically considered to be part of the human mirror neuron system (MNS). However, a recent adult study combining EEG and fMRI recordings has demonstrated that sensorimotor alpha suppression correlates significantly with the BOLD signal in motor areas such as inferior parietal lobule and dorsal premotor cortex during action observation and execution (Arnstein et al., 2011). These findings support the notion that sensorimotor alpha suppression reflects the modulation of sensorimotor cortex activation by mirror neuron areas in the parietal and frontal cortex, and suggest that it can be used as a valid indirect index of MNS activity (Arnstein et al., 2011; Hari et al., 1998; Muthukumaraswamy and Johnson, 2004a,b; Muthukumaraswamy et al., 2004; Nyström et al., 2011; Perry and Bentin, 2009). Together with the relative ease with which EEG can be used with young infants, this has made sensorimotor alpha suppression the most frequently used neural measure of action mirroring in infancy.