title: Neural activity during interoceptive awareness and its associations with alexithymia-An fMRI study in major depressive disorder and non-psychiatric controls.
abstract: OBJECTIVE
  Alexithymia relates to difficulties recognizing and describing emotions. It has been linked to subjectively increased interoceptive awareness (IA) and to psychiatric illnesses such as major depressive disorder (MDD) and somatization. MDD in turn is characterized by aberrant emotion processing and IA on the subjective as well as on the neural level. However, a link between neural activity in response to IA and alexithymic traits in health and depression remains unclear.
  
  
  METHODS
  A well-established fMRI task was used to investigate neural activity during IA (heartbeat counting) and exteroceptive awareness (tone counting) in non-psychiatric controls (NC) and MDD. Firstly, comparing MDD and NC, a linear relationship between IA-related activity and scores of the Toronto Alexithymia Scale (TAS) was investigated through whole-brain regression. Secondly, NC were divided by median-split of TAS scores into groups showing low (NC-low) or high (NC-high) alexithymia. MDD and NC-high showed equally high TAS scores. Subsequently, IA-related neural activity was compared on a whole-brain level between the three independent samples (MDD, NC-low, NC-high).
  
  
  RESULTS
  Whole-brain regressions between MDD and NC revealed neural differences during IA as a function of TAS-DD (subscale difficulty describing feelings) in the supragenual anterior cingulate cortex (sACC; BA 24/32), which were due to negative associations between TAS-DD and IA-related activity in NC. Contrasting NC subgroups after median-split on a whole-brain level, high TAS scores were associated with decreased neural activity during IA in the sACC and increased insula activity. Though having equally high alexithymia scores, NC-high showed increased insula activity during IA compared to MDD, whilst both groups showed decreased activity in the sACC.
  
  
  CONCLUSIONS
  Within the context of decreased sACC activity during IA in alexithymia (NC-high and MDD), increased insula activity might mirror a compensatory mechanism in NC-high, which is disrupted in MDD.
authors.affiliation: Cluster of Excellence in Cognitive Sciences, Department of Sociology of Physical Activity and Health, University of Potsdam Potsdam, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Wiebking
authors.affiliation: Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada ; Graduate Institute of Humanities in Medicine, Taipei Medical University Taipei, Taiwan ; Taipei Medical University-Shuang Ho Hospital, Brain and Consciousness Research Center New Taipei City, Taiwan ; Department of Psychology, National Chengchi University Taipei, Taiwan ; Center for Cognition and Brain Disorders, Normal University Hangzhou Hangzhou, China.
authors.forename: Georg
authors.initials: G
authors.lastname: Northoff
keywords: alexithymia; fMRI; insula; interoception; interoceptive awareness; major depressive disorder; neuroimaging; sACC