  In both human and monkeys the observation and execution of actions produced
the activation of a network consisting of parietal and frontal areas. Although
this network is involved in the encoding of the action goal, it does not
consider the affective component of the action: vitality form (VF). Several
studies showed that the observation and execution of actions conveying VFs
selectively activated the dorso-central insula (DCI). In the present study, we
aimed to clarify, by using Dynamic Causal Modeling (DCM), the direction of the
information flow across DCI, parieto-frontal areas (PMv, IPL) and posterior
superior temporal sulcus (pSTS) during both observation and execution of
actions conveying VFs. Results indicate that, during observation, DCI receives
the visual input from pSTS, and, in turn, sends it to the fronto-parietal
network. Moreover, DCI significantly modulates PMv. Conversely, during
execution, the motor input starts from PMv, reaches DCI and IPL, with a
significant modulation from PMv to DCI. The reciprocal exchange of information
between PMv and DCI suggests that these areas work closely together in the VFs
action processing. An additional tractography analysis corroborates our DCM
models, showing a correspondence between functional connections and anatomical
tracts.
