The neural basis of one's own conscious and unconscious emotional states

Changes in interoceptive processes following brain stimulation

“…Emotional concepts then occur by appraisal mechanisms involving other brain regions such as the anterior cingulate and the medial prefrontal cortices that refer to this mapping of the bodystate. It is a multistage interoceptive/somatosensory process by which these body state patterns are detected and assigned conceptual emotional meaning [29]. These assumptions are in accordance with other studies showing that the insular cortex and the anterior cingulate cortex (ACC) play crucial roles in connecting interoceptive processes and emotions [24].…”

“…Going beyond IAc, cTBS of right anterior insula and right somatosensory cortices led to an immediate increase in interoceptive sensibility as assessed by self-report. As former studies found a correlation between insula activation and sensibility [5], and this facet of interoceptive processing refers especially to the idea of 'whole-body' patterns as introduced by Smith & Lane [29], a modulation of interoceptive sensibility was assumed to occur after insula stimulation. The fact that cTBS inhibiting somatosensory cortices also modulated interoceptive sensibility in the same direction as cTBS over right anterior insula highlights that, within the assumed hierarchical structure of interoception, hampering a region processing a discrete body feature leads to greater 'noise' in the whole system.…”

“…This underpins its pivotal role for processes related to anticipation of aversive stimuli or anxiety disorders [55]. According to the model of Smith & Lane [29], it might be argued that inhibiting anterior insula functions could have primarily disturbed 'whole-body patterns' and therefore, the reduction of IAc becomes evident or conscious to the participants, leading to a corresponding decline in metacognitive beliefs of perception security. In a similar way, together with models of 'interoceptive prediction error', this could explain the increases of self-reported subjective feelings of anxiety and arousal and more aversive feelings after inhibition of anterior insula.…”

“…This view might also explain why an inhibition of somatosensory cortices does not systematically reduce confidence as demonstrated for cardiac and respiratory signals in this study. Leaving the anterior insula function intact does not compromise the basic integration of 'whole-body' representations, including feelings of general discomfort as described above; however, it disturbs another process that is possibly related to the evaluation/appraisal and expectations of and the matching to on-going discrete bodily reactions that have been suggested to be associated with somatosensory cortices [29]. Furthermore, tactile input from the chest might play a role in the detection of heartbeat.…”

“…Although the prior parts of the experiment were rather short (about 8 -10 min), and though there are several studies showing that cTBS effects last at least 20 min or significantly longer [44,60], it cannot be ruled out that the effects of cTBS were already diminishing when compared with the assessment of interoceptive processes in the cardiovascular system. Following Smith & Lane [29], discrete body features are represented in somatosensory cortices and disturbing these discrete features might affect the relative balance of accuracy, sensibility and confidence dimensions. Favouring this assumption, both insula and somatosensory stimulation led to an increase of interoceptive sensibility as assessed by questionnaire.…”