RESTING-STATE FMRI TO CHARACTERISE THE TEMPORAL DYNAMICS OF FUNCTIONAL CONNECTIVITY FOLLOWING REPETITIVE SUBCONCUSSIVE HEAD IMPACTS

Repetitive subconcussive head impacts (rsHI), common in football, are associated with potential long-term implications for brain health. Although rsHI typically occur without overt clinical symptoms, emerging evidence suggests they induce subtle alterations in functional brain networks. This study investigated the acute effects of rsHI on resting-state functional connectivity (rsFC), with focus on the default mode network (DMN), a network implicated in brain injury and neurocognitive vulnerability. Competitive footballers (n=7, 4 female, aged 18-35 years) with a minimum of ten years’ playing experience under-went resting-state fMRI on a 3T Siemens scanner. Participants were assigned to either a football heading or virtual reality (VR) heading control group. Groups either completed 15 headers of a real football or a football in VR (no ball to head contact). Each participant completed three scanning sessions: pre and post heading intervention, and a follow-up scan after 24 hours. rsFC data were preprocessed and analysed using the CONN toolbox, employing seed-based analysis to examine within, and between network connectivity. Preliminary findings indicate that baseline DMN connectivity (Figure 1a) showed significantly increased cerebellar and reduced Precuneous connectivity immediately after heading (Figure 1d), when comparing the heading (Figure 1b) to the VR group (Figure 1c), with full statistical analysis ongoing. These findings suggest that rsHI induces disruptions to functional network organisations, potentially reflecting altered network integration, or compensatory processes. By characterising temporal dynamics of rsFC following controlled rsHI, this study advances understanding of subtle brain injury in sport and supports rsFC as a sensitive marker of short functional changes.