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emotionality, orbitofrontal & cingulateEmotionality, orbitofrontal & cingulatePositive emotionality is associated with baseline metabolism in orbitofrontal cortex and in regions of the default network N. D. Volkow Molecular Psychiatry (2011) 16, pp. 818-25 http://www.nature.com/mp/ INTRODUCTION: This paper looks at the connections between dopamine, the orbitofrontal and cingulate cortices and their influence on positive emotionality and also resting, introspective states that are not attending much to external signals. In other studies orbitofrontal activity is related to subjective experience rather than the strength of external signals. This argues for the importance of subjective conscious in relation to positive emotionality and possible as the cogitations of the default mode. Positive emotionality in terms of well-being, sensations of enthusiasm, reward-sensitivity, motivation, achievement and social relations is seen as being related to the level of D2 dopamine receptors in the striatal area of the basal ganglia. The D2 receptors are thought to modulate the orbitofrontal cortex and the cingulate cortex, which are regions that evaluate rewards. It is therefore a hypothesis of the authors that these regions underlie positive emotionality. A study by the authors showed a correlation between positive emotionality and activity in the orbitofrontal, the cingulate and other frontal, temporal and parietal areas. There is a significant overlap with the brain’s default network, thought to handle undirected introspection, such as day dreaming, mind wandering and aspects of creativity. This is taken to suggest that positive emotionality relates to global cortical processes that are active during resting conditions. Healthy activity in the orbitofrontal and cingulate is regarded as being protective against addiction, while dysfunction in these areas is seen as the signature of addiction. Healthy activity here can protect even where there is an hereditary proneness to an addiction such as alcoholism. The neurotransmitter, dopamine, is involved in reward and motivation and is also seen as being related to positive emotionality. High striatal levels of D2 receptors are related to positive emotionality and a reduced proneness to addiction. Low striatal D2 receptors are related to addiction. Dopamine is viewed as regulating the prefrontal areas and in particular the orbitofrontal and the anterior cingulate. It is suggested that the association between striatal D2 receptors and positive emotionality is achieved via the orbitofrontal and the anterior cingulate. These last two areas are seen as encoding the value of rewards. These regions are also related to inhibition of impulses. Patients with dysfunction in these areas are prone to impulsivity. Persistence and effortful control are also related to the orbitofrontal, while social closeness is related to the anterior cingulate. |
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