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. 2021 Jun;15(3):473-480.
doi: 10.1007/s11571-020-09639-w. Epub 2020 Oct 23.

EEG power spectral density in locked-in and completely locked-in state patients: a longitudinal study

Arianna Secco  1 , Alessandro Tonin  2 , Aygul Rana  3 , Andres Jaramillo-Gonzalez  3 , Majid Khalili-Ardali  3 , Niels Birbaumer  3 , Ujwal Chaudhary  2   3
Affiliations

EEG power spectral density in locked-in and completely locked-in state patients: a longitudinal study

Arianna Secco et al. Cogn Neurodyn. 2021 Jun.

Abstract

Persons with their eye closed and without any means of communication is said to be in a completely locked-in state (CLIS) while when they could still open their eyes actively or passively and have some means of communication are said to be in locked-in state (LIS). Two patients in CLIS without any means of communication, and one patient in the transition from LIS to CLIS with means of communication, who have Amyotrophic Lateral Sclerosis were followed at a regular interval for more than 1 year. During each visit, resting-state EEG was recorded before the brain-computer interface (BCI) based communication sessions. The resting-state EEG of the patients was analyzed to elucidate the evolution of their EEG spectrum over time with the disease's progression to provide future BCI-research with the relevant information to classify changes in EEG evolution. Comparison of power spectral density (PSD) of these patients revealed a significant difference in the PSD's of patients in CLIS without any means of communication and the patient in the transition from LIS to CLIS with means of communication. The EEG of patients without any means of communication is devoid of alpha, beta, and higher frequencies than the patient in transition who still had means of communication. The results show that the change in the EEG frequency spectrum may serve as an indicator of the communication ability of such patients.

Keywords: Alpha frequency; Completely locked-in state (CLIS); LIS (locked-in state); Power spectrum density (PSD); Resting-state electroencephalogram (EEG).

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Conflict of interest statement

Conflict of interestThe authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
Schematic workflow showing EEG’s processing steps
Fig. 2
Fig. 2
EEG power spectral density evolution in Patient 6. The PSDs corresponding to different visits is shown in different colors, as explained in the box in the top right corner of the figure. The x-axis represents the frequency in Hz. The y-axis represents the normalized amplitude of the power spectral densities on a logarithmic scale. In dashed lines are shown the frequency bands of interest. The frequency range analyzed is divided in the canonical frequency bands, represented in dashed lines in the figures: delta (1 to 4 Hz), theta (4 to 8 Hz), alpha (8 to 12 Hz), beta (12 to 30 Hz) and gamma (30 to 45 Hz)
Fig. 3
Fig. 3
EEG power spectral density evolution in Patient 9. The details of the figure are the same as explained in the legend of Fig. 2
Fig. 4
Fig. 4
EEG power spectral density evolution in Patient 11. The details of the figure are the same as explained in the legend of Fig. 2
Fig. 5
Fig. 5
Comparison of average EEG power spectral densities in Patients 6, 9, and 11. The red, blue, and green traces correspond to the average PSDs at electrode Cz for patients 6, 9, and 11, respectively. The x-axis represents the frequency in Hz. The y-axis represents the normalized amplitude of the power spectral densities in the logarithmic scale. In dashed lines are shown the frequency bands of interest as described in the legend of Fig. 2
Fig. 6
Fig. 6
Relative band power at electrode Cz. Error bars represent standard deviations. The figure depicts the significant power differences between patients 6, 9, and 11 in the two-tailed Wilcoxon rank-sum test with False Discovery Rate correction are marked: *p < 0.05. The x-axis represents the different frequency bands in Hz, and the y-axis represents the relative band power
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References

    1. Babiloni C, Pistoia F, Sarà M, Vecchio F, Buffo P, Conson M, Onorati P, Albertini G, Rossini PM. Resting state eyes-closed cortical rhythms in patients with locked-in-syndrome: an EEG study. Clin Neurophysiol. 2010;121:1816–1824. - PubMed
    1. Bauer G, Gerstenbrand F, Rumpl E. Varieties of the locked-in syndrome. J Neurol. 1979;221:77–91. - PubMed
    1. Belouchrani A, Abed-Meraim K, Cardoso JF, Moulines E. A blind source separation technique using second-order statistics. IEEE Trans Signal Process. 1997;45(2):434–444.
    1. Benjamini Y, Hochberg Y. Controlling the false discovery rate: a practical and powerful approach to multiple testing. J R Stat Soc Ser B (Methodol) 1995;57(1):289–300.
    1. Birbaumer N. Breaking the silence: brain–computer interfaces (BCI) for communication and motor control. Psychophysiology. 2006;43(6):517–532. - PubMed

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