Selective Attention deficits in mild traumatic brain injury using Steady-State Visual Evoked Potentials; neural correlates of Attention

Objective To objectively quantify visuospatial selective and divided attention using steady-state visual evoked potentials (SSVEPs) in adults with persistent visual symptoms after mild traumatic brain injury (mTBI). Methods Eighteen adults with mTBI (40–350 days post-mTBI) and 27 healthy controls participated. Frequency-tagged SSVEPs to eccentric flickering stimuli along with concurrent behavioral yes/no contrast-decrement-detection task were recorded under three cued covert spatial attention conditions: Selective Attention (SelAtt), Divided Attention (DivAtt), and Ignore. EEG epochs associated with eye fixation loss were excluded using two independent procedures: automated EEG artifact-rejection algorithms and concurrent EyeLink eye-tracking data. Results The mTBI group showed no significant change in task accuracy and complex-value SSVEP responses across attentional conditions (P > 0.05). In contrast, controls showed significant improvements in task accuracy (P < 0.001) and significant SSVEP modulations across conditions (P = 0.03), with stronger SSVEP during SelAtt compared with Ignore (P = 0.008). SelAtt SSVEPs in mTBI were significantly weaker than controls (P = 0.04). Unlike mTBI, control SSVEP amplitude and inter-trial phase coherence (ITPC) significantly increased across conditions (P = 0.02 and < 0.001, respectively). Both groups did not show any significant modulation in SSVEP phase across attentional conditions (P > 0.05). The significant ITPC-amplitude correlation within each group (P < 0.001) was associated with attention status, whereby SelAtt was associated with higher neural ITPC-amplitude response. Conclusions These findings indicate impaired visuospatial selective attention in adults with persistent post-mTBI visual symptoms. Our results support neural synchronization theory on population-level neural correlates of attention and suggest impaired synchronization may underlie attention deficits in mTBI. Significance SSVEP provides objective neurophysiological indices of attentional processing in mTBI.