Stefanics, G. | bioRxiv Science

bioRxiv2023

Emotion-induced frontal α asymmetry predictsrelapse after discontinuation of antidepressantmedication

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSBackgroundC_ST_ABSOne in three patients relapse after antidepressant discontinuation. Thus, the prevention of relapse after achieving remission is an important component in the long-term management of Major Depressive Disorder (MDD). However, no clinical or other predictors are established. Frontal reactivity to sad mood as measured by fMRI has been reported to relate to relapse independently of antidepressant discontinuation and is an interesting candidate predictor. MethodsPatients (n=56) who had remitted from a depressive episode while taking antidepressants underwent EEG recording during a sad mood induction procedure prior to gradually discontinuing their medication. Relapse was assessed over a six-months follow-up period. 35 healthy controls were also tested. Current source density of the EEG power in the band (8-13Hz) was extracted and alpha-asymmetry was computed by comparing the power across two hemispheres at frontal electrodes (F5 and F6). OutcomesSad mood induction was robust across all groups. Reactivity of -asymmetry to sad mood did not distinguish healthy controls from patients with remitted MDD on medication. However, the 14 (25%) patients who relapsed during the follow-up period after discontinuing medication showed significantly reduced reactivity in -asymmetry compared to patients who remained well. This EEG signal provided predictive power (69% out-of-sample balanced accuracy). InterpretationA simple EEG-based measure of emotional reactivity may have clinical utility in the management of antidepressant discontinuation. FundingSwiss National Science Foundation project grant 320030L_153449 / 1 to QJMH, Stiftung Deutsche Depressionshilfe to HW and QJMH, a Deutsche Forschungsgemeinschaft (DFG) grant (WA 1539/5-1) to HW, EMDO Stiftung to QJMH and the Rene and Susanne Braginsky Foundation and Clinical Research Priority Programme "Molecular Imaging" at the University of Zurich to KES.

neuroscience↗

bioRxiv2018

Feature-specific prediction errors for visual mismatch support predictive coding accounts of perception

Predictive coding (PC) theory posits that our brain employs a predictive model of the environment to infer the causes of its sensory inputs. A fundamental but untested prediction of this theory is that the same stimulus should elicit distinct precision weighted prediction errors (pwPEs) when different (feature-specific) predictions are violated, even in the absence of attention. Here, we tested this hypothesis using functional magnetic resonance imaging (fMRI) and a multi-feature roving visual mismatch paradigm where rare changes in either color (red, green), or emotional expression (happy, fearful) of faces elicited pwPE responses in human participants. Using a computational model for learning and inference, we simulated pwPE trajectories of a Bayes-optimal observer and used these to analyze changes in blood oxygen level dependent (BOLD) responses to changes in color and emotional expression of faces while participants engaged in a distractor task. Controlling for visual attention by eye-tracking, we found pwPE responses to unexpected color changes in the fusiform gyrus. Conversely, unexpected changes of facial emotions elicited pwPE responses in thalamo-cortico-cerebellar structures associated with emotion processing. Our results support a general role of PC across perception, from low-level to complex and socially relevant object features, and suggest that monitoring of the social environment occurs continuously and automatically, even in the absence of attention.\n\nHighlightsPredictive coding (PC) implies that brain responses should reflect transient precision weighted prediction errors (pwPEs). By using fMRI we show that rare changes in color or emotional expression of human faces elicit pwPE responses in dedicated neuronal circuits with known specialization in processing color and emotion-related information, respectively. Our results demonstrate that physically identical stimuli elicit pwPEs in distinct neuronal circuits when different (feature-specific) predictions are violated, depending on current sensory expectations based on prior stimulus context. The demonstration of pwPEs in visual areas as well as in emotion processing structures lends experimental support to theoretical accounts of PC in color and social perception, respectively.

neuroscience↗