Brain Activity Correlates With Cognitive Performance Deterioration During Sleep Deprivation

We studied the correlation between oscillatory brain activity and performance in healthy subjects performing the error awareness task (EAT) every two hours, for 24 hours. In the EAT, subjects were shown on a screen the names of colors and were asked to press a key if the name of the color and the color it was shown in matched, and the screen was not a duplicate of the one before (‘Go’ trials). In the event of a duplicate screen (‘Repeat No-Go’ trial) or a color mismatch (‘Stroop No-Go’ trial), the subjects were asked to withhold from pressing the key. We assessed subjects’ (N=10) response inhibition by measuring accuracy of the ‘Stroop No-Go’ (SNGacc) and ‘Repeat No-Go’ trials (RNGacc). We assessed their reactivity by measuring reaction time in the ‘Go’ trials (GRT). Simultaneously, nine electroencephalographic (EEG) channels were recorded (Fp2, F7, F8, O1, Oz, Pz, O2, T7, and T8). The correlation between reactivity and response inhibition measures to brain activity was tested using quantitative measures of brain activity based on the relative power of gamma, beta, alpha, theta, and delta waves. In general, response inhibition and reactivity reached a steady level between 6 and 16 hours of sleep deprivation, which was followed by sustained impairment after 18 hours. Channels F7 and Fp2 had the highest correlation to the indices of performance. Measures of response inhibition (RNGacc and SNGacc) were correlated to the alpha and theta waves’ power for most of the channels, especially in the F7 channel (r = 0.82 and 0.84, respectively). The reactivity (GRT) exhibited the highest correlation to the power of gamma waves in channel Fp2 (0.76). We conclude that quantitative measures of EEG provide information that can help us to better understand changes in subjects’ performance and could be used as an indicator to prevent the adverse consequences of sleep deprivation.