Gamma oscillations of visual cortex underlying emotion and cognition deficits associated with suicide attempt in major depressive disorder

Altered neural oscillations in response to negative or positive emotional stimuli may be related to severe clinical symptoms in patients with major depressive disorder, particularly high suicidality. However, the underlying neurobiological mechanisms of this aberrant oscillatory activity and its potential emotional and cognitive functions remain unclear. Here we conducted a cross-sectional study of 107 participants, including 40 healthy controls and 67 patients with major depressive disorder (33 with suicide attempts and 34 without). All participants underwent an emotional expression recognition task during the magnetoencephalography scanning and completed neurocognitive assessments. Time–frequency characteristics and phase connections were analysed and compared between groups in sensor and source space using cluster-based permutation tests. The association between abnormal oscillatory features and neurocognitive performance was also evaluated. We found that increased gamma oscillations (50–70 Hz) of the visual cortices were considerably associated with suicide attempts in depression. Moreover, gamma-band source power in happy or sad conditions could predict individualized suicide risk. Gamma-band phase connections under the happy or sad condition were related to deficits in large-scale cognitive functions. Overall, gamma oscillations of the visual areas induced by the emotional stimuli were reliable biomarkers for identifying suicide attempts in depressive patients. Abnormal gamma-band connection involving visual cortex under both happy and sad expressions were significantly correlated with broad cognitive deficits. The authors investigate neural oscillations, measured by magnetoencephalography, in response to emotionally valenced stimuli as a potential biomarker characterizing individuals with major depressive disorder who had previously made a suicide attempt.