Friday, September 11, 2015

Thinking too much - Self generated thought as the engine of neuroticism.

Perkins et al. offer an opinion piece in which they propose that the cost and benefits of neuroticism are surface manifestations of a tendency to engage in negatively hued self generated thought. I pass on their abstract and text from one of their figures:
•Existing neuroticism models cannot explain its link to both unhappiness and creativity. 
•Self-generated thought (SGT) facilitates creativity but can cause unhappiness. 
•Threat-related regions of medial prefrontal cortex (mPFC) generate blue-tinted SGT. 
•High neuroticism may reflect proneness to SGT arising from mPFC hyperactivity. 
Neuroticism is a dimension of personality that captures trait individual differences in the tendency to experience negative thoughts and feelings. Established theories explain neuroticism in terms of threat sensitivity, but have limited heuristic value since they cannot account for features of neuroticism that are unrelated to threat, such as creativity and negative psychological states experienced in benign, threat-free environments. We address this issue by proposing that neuroticism stems from trait individual differences in activity in brain circuits that govern the nature of self-generated thought (SGT). We argue our theory explains not only the association of neuroticism with threat sensitivity but also the prominence within the neurotic mind of representations of information that are unrelated to the way the world is right now, such as creativity and nonsituational ‘angst’.
A figure legend from the text (graphics did not have resolution adequate to display here):

Neuroticism, self-generated thought (SGT) and perceptions of threat intensity. (A) If an individual with ventromedial prefrontal cortex (vmPFC)/basolateral nuclei of the amygdala (BLA) that is twice as reactive as that of the average person switches from anxiety to panic when a spider encroaches within 4 m (an early switcher), then an average person will switch from anxiety to panic only when that same spider encroaches within 2 m (an ‘average switcher’). Conversely, a person with vmPFC/BLA that is half as reactive as that of the average person will switch from anxiety to panic only when that same spider encroaches within 1 m (a ‘late switcher’). The same psychological state (panic) is achieved in each individual, but the physical distance to threat that elicits it is different. (The graphic showed approaching spider.)(B) A model of how neuroticism is driven by individual differences in susceptibility to negatively hued SGT. Individuals who happen to have greater spontaneous activity in regions of mPFC associated with threat perception, experience frequent, spontaneous activation of threat-related amygdala circuits in situations that are wholly nonthreatening. (The graphic was picture of flowers.) In individuals who also happen to have a highly reactive vmPFC/BLA, these activations are likely to be sufficiently intense to be debilitating; therefore, such individuals present as being highly neurotic.

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