Why am I lagging? Reduced dynamics of perception and occipital cortex in depression

Abstract

Major depressive disorder (MDD) is characterized by reduced dynamic with abnormal slowness in emotion, thought/cognition, and movements. Is the reduced dynamic also manifest in visual perception and neural activity of occipital cortex? Various findings show reduced activity in occipital cortex including in subareas like human MT complex (hMT+) cortex in MDD; its meaning for the dynamics of visual perception in MDD remains yet unclear, though. Combining novel data in three independents acute MDD samples (totally, 109 MDD, 113 HC), we characterize hMT+ in MDD in a dynamic way on perceptual (visual motion paradigm) and neural (rest/task fMRI) levels. Our main findings in MDD are: (i) reduced duration threshold difference for discriminating fast and slow-speed stimuli, leading to (ii) the perception of a longer distance for faster-speed moving gratings; (iii) reduced global representation of the brain’s spontaneous activity in hMT+ in especially faster infra slow frequencies with reverberation to subcortical and higher-order cortical regions; (iv) reduced beta value in hMT+ and higher-order cortical regions to especially faster visual stimuli; (v) correlation of these psychophysical and neural changes with symptom severity. We demonstrate reduced occipital activity in faster timescales on perceptual, and neural levels. Occipital cortex (hMT+) activity in MDD is characterized by reduced dynamics which shapes these subjects’ visual perception in an abnormal way. Beyond further establishing a basic dynamic deficit characterizing the visual system in MDD on both neural and perceptual levels, our results provide clinical opportunities for occipital-based diagnostic markers and novel therapeutic interventions in MDD.