<p class="first" id="P1">Connectivity in intrinsically connected networks (ICN) may
predict individual differences
in cognition and behavior. The drastic alterations in socioemotional awareness of
patients with behavioral variant frontotemporal dementia (bvFTD) are presumed to arise
from changes in one such ICN, the salience network (SN). We examined how individual
differences in SN connectivity are reflected in overt social behavior in healthy individuals
and patients, both to provide neuroscientific insight into this key brain-behavior
relationship, and to provide a practical tool to diagnose patients with early bvFTD.
We measured SN functional connectivity and socioemotional sensitivity in 65 healthy
older adults and 103 patients in the earliest stage (Clinical Dementia Rating Scale
score ≤1) of five neurodegenerative diseases (14 bvFTD, 29 Alzheimer’s disease, 20
progressive supranuclear palsy, 21 semantic variant primary progressive aphasia, and
19 non-fluent variant primary progressive aphasia). All participants underwent resting-state
functional imaging and an informant described their responsiveness to subtle emotional
expressions using the Revised Self-Monitoring Scale (RSMS). Higher functional connectivity
in the SN, predominantly between the right anterior insula (AI) and both “hub” cortical
and “interoceptive” subcortical nodes, predicted socioemotional sensitivity among
healthy individuals, showing that socioemotional sensitivity is a behavioral marker
of SN function, and particularly of right AI functional connectivity. The continuity
of this relationship in both healthy and neurologically affected individuals highlights
the role of socioemotional sensitivity as an early diagnostic marker of SN connectivity.
Clinically, this is particularly important for identification of patients in the earliest
stage of bvFTD, where the SN is selectively vulnerable.
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