Neural correlates of processing emotional prosody in unipolar depression

Abstract

Major depressive disorder (MDD) is characterized by a biased emotion perception. In the auditory domain, MDD patients have been shown to exhibit attenuated processing of positive emotions expressed by speech melody (prosody). So far, no neuroimaging studies examining the neural basis of altered processing of emotional prosody in MDD are available. In this study, we addressed this issue by examining the emotion bias in MDD during evaluation of happy, neutral, and angry prosodic stimuli on a five-point Likert scale during functional magnetic resonance imaging (fMRI). As expected, MDD patients rated happy prosody less intense than healthy controls (HC). At neural level, stronger activation in the middle superior temporal gyrus (STG) and the amygdala was found in all participants when processing emotional as compared to neutral prosody. MDD patients exhibited an increased activation of the amygdala during processing prosody irrespective of valence while no significant differences between groups were found for the STG, indicating that altered processing of prosodic emotions in MDD occurs rather within the amygdala than in auditory areas. Concurring with the valence-specific behavioral effect of attenuated evaluation of positive prosodic stimuli, activation within the left amygdala of MDD patients correlated with ratings of happy, but not neutral or angry prosody. Our study provides first insights in the neural basis of reduced experience of positive information and an abnormally increased amygdala activity during prosody processing.

CACNA1C risk variant affects microstructural connectivity of the amygdala

“…For alexithymia, a reduced neural response to emotional prosody within the right STG and the bilateral amygdala was shown ( Goerlich-Dobre et al, 2013 ). In a recent study, we demonstrated an increased neural activation of the amygdala during prosody processing in patients with MDD as compared to HC, while no differences between groups were found for the STG/MTG ( Koch et al, 2018 ). Although these studies suggest some variation regarding regional changes in activation, STG and amygdala emerge as most frequently involved brain areas across different psychiatric disorders.…”

“…Thus, the combined structural and functional results of our study indicate that the risk allele is associated with alterations of microstructure rather than functional activation of the amygdala as potential early neurobiological substrate for the development of affective disorders. Changes in functional activation and corresponding behavior as observed in depressed patients ( Koch et al, 2018 ) might occur only when the affective disorders already manifested itself as e.g. demonstrated for risk allele carriers with bipolar disorder ( Tesli et al, 2013 ).…”

“…In the acoustic domain, socially relevant cues can be expressed verbally (semantic information) and nonverbally by modulation of speech melody (prosody). Nonverbal communication enables inferences about the emotional state of the speaker and it has been demonstrated that perception of emotional prosody is impaired in several psychiatric disorders including schizophrenia (SCZ, ( Bozikas et al, 2006 ; Gold et al, 2012 ; Hoertnagl et al, 2014 ), bipolar disorder (BD, ( Bozikas et al, 2007 ; Hoertnagl et al, 2014 ), major depressive disorder (MDD, ( Kan et al, 2004 ; Koch et al, 2018 ; Liu et al, 2012 ; Naranjo et al, 2011 ; Schlipf et al, 2013 ), and attention deficit hyperactivity disorder (ADHD, ( Bisch et al, 2016 ; Grabemann et al, 2013 ; Kis et al, 2017 ).…”

“…Additionally, we also explored axial diffusivity (AD) and radial diffusivity (RD). Based on previous structural and functional studies regarding changes associated with the CACNA1C risk allele rs1006737 (for a review, see ( Ou et al, 2015 )), as well as own examinations on processing of prosody in depressed patients ( Koch et al, 2018 ), we hypothesize that such alterations would affect the amygdala, but not the temporal voice areas. Examining genetic risk variants in healthy individuals represents a promising strategy that can pave the way for a better understanding of the mechanisms underlying altered perception and neural processing of emotions in psychiatric patient populations without being compromised by typical confounding variables, such as disease duration, medication or epistasis with other risk alleles (for a similar approach see ( Wessa et al, 2010 )).…”

The conscious processing of emotion in depression disorder: a meta-analysis of neuroimaging studies

“…Li et al ( 17 ) found that the abnormal activated brain regions including the dorsolateral prefrontal cortex and temporal gyrus were responsible for the altered performance during the explicit emotion task. In another study ( 18 ), the brain abnormalities primarily focused on the cerebellum, precentral gyrus, amygdala, insula, and others. Briceño et al ( 19 ) discovered a decreased activation on the precuneus in depressive patients during emotion-recognition tasks.…”