Interoception in insula subregions as a possible state marker for depression-an exploratory fMRI study investigating healthy, depressed and remitted participants.
BACKGROUND
Interoceptive awareness (iA), the awareness of stimuli originating inside the body, plays an important role in human emotions and psychopathology. The insula is particularly involved in neural processes underlying iA. However, iA-related neural activity in the insula during the acute state of major depressive disorder (MDD) and in remission from depression has not been explored.


METHODS
A well-established fMRI paradigm for studying (iA; heartbeat counting) and exteroceptive awareness (eA; tone counting) was used. Study participants formed three independent groups: patients suffering from MDD, patients in remission from MDD or healthy controls. Task-induced neural activity in three functional subdivisions of the insula was compared between these groups.


RESULTS
Depressed participants showed neural hypo-responses during iA in anterior insula regions, as compared to both healthy and remitted participants. The right dorsal anterior insula showed the strongest response to iA across all participant groups. In depressed participants there was no differentiation between different stimuli types in this region (i.e., between iA, eA and noTask). Healthy and remitted participants in contrast showed clear activity differences.


CONCLUSIONS
This is the first study comparing iA and eA-related activity in the insula in depressed participants to that in healthy and remitted individuals. The preliminary results suggest that these groups differ in there being hypo-responses across insula regions in the depressed participants, whilst non-psychiatric participants and patients in remission from MDD show the same neural activity during iA in insula subregions implying a possible state marker for MDD. The lack of activity differences between different stimulus types in the depressed group may account for their symptoms of altered external and internal focus.
Cluster of Excellence in Cognitive Sciences, Department of Sociology of Physical Activity and Health, University of Potsdam Potsdam, Germany ; Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada.
Christine
C
Wiebking
Department of Psychosomatic Medicine and Psychotherapy, University Medicine Mainz Mainz, Germany.
Moritz
M
de Greck
Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada ; Centre for Cognition and Brain Disorders, Hangzhou Normal University Hangzhou, China ; Graduate Institute of Humanities in Medicine, Taipei Medical University Taipei, Taiwan ; Brain and Consciousness Research Center, Taipei Medical University-Shuang Ho Hospital New Taipei City, Taiwan.
Niall W
NW
Duncan
Department of Neurology, Otto-von-Guericke University Magdeburg Magdeburg, Germany.
Claus
C
Tempelmann
Cluster of Excellence "Languages of Emotion" and Dahlem Institute for Neuroimaging of Emotion, Freie Universität Berlin Berlin, Germany ; Department of Psychiatry, Charité-Universitätsmedizin, Campus Benjamin Franklin Berlin, Germany.
Malek
M
Bajbouj
Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada ; Centre for Cognition and Brain Disorders, Hangzhou Normal University Hangzhou, China ; Graduate Institute of Humanities in Medicine, Taipei Medical University Taipei, Taiwan ; Brain and Consciousness Research Center, Taipei Medical University-Shuang Ho Hospital New Taipei City, Taiwan ; Department of Psychology, National Chengchi University Taipei, Taiwan.
Georg
G
Northoff
fMRI; hopelessness; insula; interoception; interoceptive awareness; major depressive disorder; neuroimaging; remission