Increased cortical excitability and reduced brain response propagation during attentional lapses

Modern lifestyle curtails sleep and increases nighttime work and leisure activities. This has a deleterious impact on vigilance and attention, exacerbating chances of committing attentional lapses, with potential dramatic outcomes. A full characterization of the brain mechanisms associated with lapses is still lacking. Here, we investigated the brain signature of attentional lapses and assessed whether cortical excitability and brain response propagation were modified during lapses and whether these modifications changed with aging. We compared electroencephalogram (EEG) responses to transcranial magnetic stimulation (TMS) during lapse and no-lapse periods while performing a continuous attentional/vigilance task at night, after usual bedtime. Data were collected in healthy younger (N=12; 18-30 y) and older individuals (N=12; 50-70 y) of both sexes. Amplitude and slope of the first component of the TMS-Evoked Potential (TEP) and Response Scattering (ReSc) were used to assess cortical excitability and brain response propagation, respectively. In line with our predictions, TEP during lapses was characterized by larger amplitude and slope. We further found that ReSc over the cortical surface was lower during lapses. Importantly, cortical excitability increase and response propagation decrease during lapse did not significantly differ between age groups. These results demonstrate that attentional lapses are associated with transient increase of excitability, and decrease in response propagation and effective connectivity. This pattern is similar to what is observed during sleep, suggesting that lapses reflect a sleep-like phenomenon. These findings could contribute to develop models aimed to predicting and preventing lapses in real life situations.