Interoceptive Awareness and the Insula – Application of Neuroimaging Techniques in Psychotherapy

Abstract

Interoceptive awareness is defined as the awareness of stimuli originating inside one’s own body such as the heartbeat. The emergence of new brain imaging techniques like functional magnetic resonance imaging (fMRI) or magnetic resonance spectroscopy (MRS) has increased our knowledge of neural substrates underlying interoceptive awareness. In particular, the bilateral brain structure of the insula has been identified as a key region involved in interoceptive processes in healthy populations. In line with prominent theories of human emotion, the insula has an important function in connecting interoceptive awareness with affective experience. This connection hinging on the insula between interoception and emotional processing is suggestive of an involvement of the insula in mood disorders such as major depressive disorder (MDD). Multilayered deficits in the insula cortex of depressed individuals such as abnormal function, biochemistry, and anatomy support this hypothesis. The aim of the present article is a) to describe the importance of the insula for the interplay between interoception and emotional processing and b) how this might be figured into psychotherapeutic treatment of depressed patients using new imaging techniques like real-time fMRI. The article begins with a brief introduction about neuroanatomical settings of the insula (I. Introduction–Neuroanatomical background of the insula). Afterwards, early behavioral studies to investigate interoceptive awareness are described (II. A step Back–First attempts to investigate interoceptive awareness), followed by a description of more recent imaging studies outlining neural mechanisms underlying interoceptive awareness and emotional processing in the insula (III. The insula as key region involved in functional interoception and emotion.) Throughout, the article addresses the question of why the investigation of individuals suffering from depression might provide novel insights into the neural underpinnings of interoceptive awareness and its link to abnormal behavior (IV. Why study interoceptive awareness in depressed participants?). Following the description of a selected study that combines for the first time functional results of interoception (using fMRI) with biochemical results of the insula (using MRS) (V. Neuroimaging in interoceptive awareness combining fMRI and MRS – A specific study), the article concludes with a perspective outlining the potential for using imaging techniques like real-time fMRI to enhance neural activity in the insula during interoceptive awareness. This approach potentially leads to faster recovery in depressed patients and might be the first therapeutic application of functional imaging in psychiatry (VI. Perspectives: Neurofeedback in major depression using real-time fMRI).