Disrupted neural response timing and duration during hand movement preparation in schizophrenia spectrum disorder: An fMRI study.

Schizophrenia spectrum disorders (SSD) feature deficits in movement intention, predictive mechanisms, and agency. While prior work characterised BOLD amplitude during movement preparation and temporal dynamics across the entire movement period, it remains unknown whether preparatory neural (BOLD) response timing and duration are selectively impaired in SSD. We analysed fMRI data from 20 SSD patients and 20 healthy controls during active and passive hand movements with video feedback (own vs. other hand). Preparatory and executory BOLD responses were modelled separately using the canonical HRF and its temporal (TD) and dispersion (DD) derivatives to evaluate timing and duration. Patients with SSD showed pronounced preparatory abnormalities under own-hand feedback, including delayed responses in right supplementary motor area during active movement preparation. Passive- and active-specific timing was reversed (earlier/later) in the left (caudate, middle temporal gyrus, superior parietal gyrus) and right (postcentral gyrus, right precentral gyrus, anterior cingulate cortex). Response duration showed reduced/reversed modulation (shorter/longer) in the right supplementary motor area, bilateral supramarginal gyrus, left inferior parietal cortex, and bilateral middle temporal gyrus. Earlier response timing in right precentral gyrus during active own-hand were negatively correlated with delusions of being controlled and formal thought disorder. No group differences emerged during execution.