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No one has attempted to quantify the underpinnigs of grief using neuroimaging research until a recent collaborative effort from researchers at the University of Arizona and Munich in an article in the American Journal of Psychiatry. Grief is a highly personal experience that is potentially difficult to elicit in the artificial neuroimaging environment. In a recent study, grief was elicited in bereaved women through photographs of the deceased versus a stranger, combined with words specific to the death event versus neutral words.
Grief is a complex cognitive, emotional, and physiological state, it was anticipated that grief would be mediated by a distributed network of structures that would include, but not be restricted to activity in the posterior cingulate cortex, anterior cingulate cortex, and prefrontal cortex. Reaserch confirmed that 3 brain regions were independently activated by the picture and word factors: the posterior cingulate cortex, medial/superior frontal gyrus, and cerebellum. The two factors also activated distinct regions: for the picture factor, they were the cuneus, superior lingual gyrus, insula, dorsal anterior cingulate cortex, inferior temporal gyrus, and fusiform gyrus; and for the word factor, they were the precuneus, precentral gyrus, midbrain, and vermis. The interaction of the two factors showed significant activation in the cerebellar vermis.
Interestingly enough, this distributed neural network subserves affect processing, mentalizing, episodic memory retrieval, processing of familiar faces, visual imagery, autonomic regulation, and modulation/coordination of these functions. This neural network may account for the unique, subjective quality of grief and provide new leads in understanding the health consequences of grief and the neurobiology of attachment.
Results from the study showed that while the combination of the picture of the deceased and the grief-related words evoked the most intense grief response, the picture of the deceased elicited a moderate grief response when paired with the neutral word. Similarly, the grief-related word elicited a moderate grief response even when paired with the picture of the stranger. As such, the person factor and the word factor provide different routes into the neurobiological state of grief. These two perspectives provide both similar and dissimilar information about the neural substrates of grief, analogous to a radiologic examination of a given anatomical structure from more than one viewing angle.
This finding that a significant activation in the left medial frontal gyrus corresponds to the regions associated with mentalizing, i.e., representing one’s own and others’ mental states suggests that the participants reflected on their own state of mind, as well as that of the person in the picture, during the elicitation of grief. This is suggestive of Bowlby who viewed grief as a natural expression of what he called the "attachment behavioral system," evoked to discourage prolonged separation of an individual from a primary attachment figure. Activation of the caudate nucleus was found during a functional neuroimaging study of romantic love In the current study, they also observed activation of the caudate nucleus may reflect activation of automatic motor programs, associated with the feeling of "being drawn toward" the person depicted. If so, the caudate nucleus may contribute to the attachment system hypothesized by Bowlby.
Quantifying emotions that have never been previously catalogued adds to our library of understanding about how our brain works and contributes to our attempt to define the mind-brain connection. Grief is a universal fact of life and we are discovering that it is, in reality, a complex set of interactions involving affect and neurobiology.
Bowlby bibliography
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