http://rstb.royalsocietypublishing.org/content/371/1708/20160006.abstract
Abstract
Interoception
is a complex process encompassing multiple dimensions, such as
accuracy, learning and awareness. Here, we examined whether each of
those dimensions relies on specialized neural regions distributed
throughout the vast interoceptive network. To this end, we obtained
relevant measures of cardiac interoception in healthy subjects and
patients offering contrastive lesion models of neurodegeneration and
focal brain damage: behavioural variant fronto-temporal dementia
(bvFTD), Alzheimer's disease (AD) and fronto-insular stroke. Neural
correlates of the three dimensions were examined through structural and
functional resting-state imaging, and online measurements of the
heart-evoked potential (HEP). The three patient groups presented
deficits in interoceptive accuracy, associated with insular damage,
connectivity alterations and abnormal HEP modulations. Interoceptive
learning was differentially impaired in AD patients, evidencing a key
role of memory networks in this skill. Interoceptive awareness results
showed that bvFTD and AD patients overestimated their performance; this
pattern was related to abnormalities in anterior regions and associated
networks sub-serving metacognitive processes, and probably linked to
well-established insight deficits in dementia. Our findings indicate how
damage to specific hubs in a broad fronto-temporo-insular network
differentially compromises interoceptive dimensions, and how such
disturbances affect widespread connections beyond those critical hubs.
This is the first study in which a multiple lesion model reveals
fine-grained alterations of body sensing, offering new theoretical
insights into neuroanatomical foundations of interoceptive dimensions.
This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’.
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