Sequence-dependent effects of iTBS and perceptual learning on binocular balance

Sensory eye dominance (SED) reflects imbalanced treatment of the two eyes' inputs by the brain. Both V1-targeted intermittent theta-burst stimulation (iTBS) and dichoptic perceptual learning (PL) can reduce SED, implicating primary visual cortex (V1); however, how these interventions interact and whether they interact in an order-dependent manner remains unknown. Forty-four healthy control (HC) adults completed three daily sessions receiving either iTBS followed by PL (iTBS-PL) or PL followed by iTBS (PL-iTBS). We indexed observers' SED and motion discrimination thresholds before and after each session. SED decreased across sessions only for observers who received iTBS before PL. Motion thresholds were reduced similarly in both groups. These findings reveal an order-dependent facilitatory interaction between the two paradigms and support a causal, initiating role of V1 state in PL-driven SED plasticity rather than its implication as a byproduct of learning.