Causal disconnectomics of motion perception: insights from TMS-induced BOLD responses

Abstract

Understanding how focal perturbations lead to large-scale network (re)organization is essential for accurately predicting the behavioral consequences of brain lesions. In this study, we applied a virtual lesion approach by means of short bursts of 10 Hz transcranial magnetic stimulation (TMS) over either early visual areas (EVA) or the medio-temporal area (MT) in healthy participants, while acquiring concurrent functional MRI. TMS delivered during the early stages of motion processing selectively impaired direction discrimination at both sites, while global motion perception remained unaffected. These behavioral effects were accompanied by a common local increase in BOLD activity, but distinct patterns of network reorganization. Perturbation of EVA led to more robust and efficient functional adaptation, suggesting greater resilience to focal disruption. In contrast, behavioral impairments following MT stimulation were associated with a less organized, more random network structure. Together, these findings underscore the potential of TMS-fMRI coupling as a powerful approach for mapping causal disconnectomics--the dynamic relationships between localized neural disruption and widespread functional and behavioral outcomes providing a better understanding of lesion-induced brain changes in neurological disorders such as stroke. HighlightsO_LITMS-induced perturbation of the early visual areas (EVA) or the mediotemporal area (MT) area selectively impairs motion direction discrimination. C_LIO_LIThe TMS perturbation is associated with a context-dependent local up-scaling of BOLD activity in both areas. C_LIO_LIThe two visual areas display distinct topological networks adaptation in response to TMS, reflecting different levels of network resilience to a focal lesion. C_LIO_LITMS-fMRI coupling can be used to assess causal disconnectomics and to precisely map how a local perturbation propagates to large-scale behavioural deficits. C_LI