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Erratum to: Delta rhythmicity is a reliable EEG biomarker in Angelman syndrome: a parallel mouse and human analysis
Journal of Neurodevelopmental Disorders volume 9, Article number: 30 (2017)
The original article was published in Journal of Neurodevelopmental Disorders 2017 9:17
After publication of our article , we became aware that there were two minor data loading and analysis scripting errors in the human EEG data processing pipeline. These errors affected the channel loading/grouping and sleep/wake coding of EEG data. We have re-analysed all the data affected by these errors. The errors do not affect any interpretations or conclusions, thus no changes to the text are required apart from correcting p values and raw values affected by the errors. There are no changes to statistical significance or lack-thereof. The errors affect data presented in Fig. 3, Fig. 4, Fig. 5, and Additional file 3: Figure S3 and thus we have re-plotted these figures (see below).
More information on the errors:
The first error was in the script used to load and pre-process a subset of neurotypical EEG files. This error affected only neurotypical EEG files, as their raw formatting was different from Angelman syndome (AS) EEG files. The error in the loading script resulted in nine channels being mislabelled. The erroneous channel mapping was as follows:
Reported channel/Actual channel
For analysis, we averaged all data by region (i.e. O1 and O2 = occipital). Therefore only the three channels noted above with an asterisk were loaded in a way that impacted data analysis. This error affected a subset of neurotypical data presented in Fig. 3, Fig. 4, Fig. 5, and Additional file 3: Figure S3. We have corrected these figures, re-run all statistical tests, and corrected p values as detailed below.
In Table 1 the wakeful EEG length of 18.2 ± 2.3 min for children with Angelman syndrome should be replaced by 15.1 ± 2.3 min.
In the subsection “Children with Angelman syndrome exhibit enhanced delta power and dynamics” the last sentence should read: “As some antiepileptic medications are known to cause EEG slowing , we confirmed that the two children with AS not taking medication displayed elevated delta power (awake occipital relative delta power in NT, 18.2 ± 0.7%, in AS 37.9 ± 1.6%; in child 1, age 4, 49.5%; in child 2, age 5, 53.1%.”
In the first paragraph of the subsection “Delta power in Angelman syndrome is age-dependent” p = 0.0011 should read p = 0.0003, p = 0.041 should read p = 0.044, p = 0.0801 should read p = 0.2862, p = 0.069 should read p = 0.052, and p =0.769 should read p = 0.962.
In the second paragraph of the same subsection, p = 0.0003 should read p = 0.0009, p =0.458 should read p = 0.356, p = 0.658 should read p =0.775, p = 0.259 should read p =0.188, and p =0.645 should read p = 0.894.
In the figure legend for Fig. 5, p = 0.0002 should read p < 0.0001, and p = 0.0007 should read p < 0.0001.
The second error was in reading files containing sleep/wake annotations. These files contained time stamps followed by a code indicating “sleep”, “wake”, or “drowsy/unsure”. All sleep data were loaded correctly and were not affected by this error. The error occurred in a subset of wake data. A subset of EEGs that we reported as “awake” also included short periods of “drowsy/unsure.” Correcting this error resulted in tiny adjustments to the values of delta and the power spectra reported. These adjustments may not be visible beyond perhaps a “jitter” of a few AS data points in Fig. 5a–d. A smaller subset (3) of EEGs that we reported as “awake” did include periods of defined sleep, and this has now been corrected.
The corrected figures are as follows:
Sidorov MS, Deck GM, Dolatshahi M, Thibert RL, Bird LM, Cui CJ, Philpot BD. Delta rhythmicity is a reliable EEG biomarker in Angelman syndrome: a parallel mouse and human analysis. Journal of Neurodevelopmental Disorders. 2017;9:17. doi:10.1186/s11689-017-9195-8.
Power spectra from all regions during epochs of wake and sleep. Black: neurotypical (NT), red: AS. During wakefulness (NT: n = 54, AS: n = 26), a occipital, b temporal, c parietal, d central, and e frontal spectra. During sleep (NT: n = 54, AS: n = 13), f occipital, g temporal, h parietal, i central, and j frontal spectra. (DOC 138 kb)
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Sidorov, M.S., Deck, G.M., Dolatshahi, M. et al. Erratum to: Delta rhythmicity is a reliable EEG biomarker in Angelman syndrome: a parallel mouse and human analysis. J Neurodevelop Disord 9, 30 (2017) doi:10.1186/s11689-017-9210-0