DOI: 10.6084/m9.figshare.24058848
title: Noreika_Motor_tDCS

description: Dream EEG and Mentation (DREAM) dataset=======================================<br>Dataset information-------------------- Common name: Noreika_Motor_tDCS- Full name: Transcranial direct current stimulation over the sensorimotor cortex during REM sleep dreaming- Authors: Valdas Noreika, Jennifer M. Windt, Katja Valli, Antti Revonsuo, Bigna Lenggenhager- Location: Turku, Finland- Year: 2020- Set ID: 15- Amendment: 0- Corresponding author ID: 2<br>Previous publications: Noreika, V., Windt, J.M., Kern, M., Valli, K., Salonen, T., Parkkola, R., Revonsuo, A., Karim, A.A., Ball, T. and Lenggenhager, B., 2020. Modulating dream experience: Noninvasive brain stimulation over the sensorimotor cortex reduces dream movement. Scientific Reports, 10(1), pp.1-19. https://doi.org/10.1038/s41598-020-63479-6<br>Correspondence: Valdas Noreika, valnoreika@gmail.com OR v.noreika@qmul.ac.uk<br>Metadata--------- Key ID: 16- Date entered: 2022-06-09T09:51:17+00:00- Number of samples: 49- Number of subjects: 10- Proportion REM: 100%- Proportion N1: 0%- Proportion N2: 0%- Proportion W: 0%- Proportion experience: 100%- Proportion no-experience: 0%- Proportion healthy: 100%- Provoked awakening: Yes- Time of awakening: Night- Form of response: Structured- Date approved: 2023-06-09T12:01:22+00:00<br>How to decode data files------------------------File 'Reports' contains participants' responses to the Bodily Experiences in Dreams (BED) Questionnaire. Please note, responses 1-49 match EEG files 1-49. In addition, there is one response, No. 50, which does not have associated EEG file.The BED Questionnaire can be found at (see pages 8-13): https://static-content.springer.com/esm/art:10.1038/s41598-020-63479-6/MediaObjects/41598_2020_63479_MOESM1_ESM.pdf<br>### Treatment group codes ###<br>* 1=Sham-stimulation* 2=Sensorimotor tDCS stimulation<br>Experimental description------------------------The study protocol consisted of a recruitment and screening session, an MRI session, and two sleep sessions on non-consecutive nights (see Fig. 1A in Noreika et al., 2020). In addition, a TMS assessment of motor cortical excitability took place on the evening of the first sleep session. Ten participants were awakened from REM sleep two or three times per night and asked to give free dream reports and answer the Bodily Experiences in Dreams (BED) Questionnaire, which targeted the dream immediately preceding awakening (see Fig. 1B in Noreika et al., 2020). Participants received sham-stimulation during REM sleep on one night and bihemispheric tDCS on the other night. Bihemispheric tDCS montage included a cathode placed over the left sensorimotor cortex and an anode placed over the right sensorimotor cortex (see Fig. 1C in Noreika et al., 2020). In addition to standard polysomnography, central and peripheral electrophysiological data were recorded using 16 electroencephalography (EEG) channels and 4 EMG channels measuring flexor and deltoid muscles in both arms.<br>### DREAM categorization procedure ###<br>All reports contain dreams - verbally reported subjective experiences during sleep. The key dependent variable in the study was answers to the Bodily Experiences in Dreams (BED) Questionnaire. For more details, see the associated ExperimentalDescription.txt and/or https://doi.org/10.1038/s41598-020-63479-6<br>Technical details-----------------Recordings contain:- 16 EEG channels (standard labels)- 4 EOG channels (Eh1 and Eh2 recorded horizontal eye movements, and Ev1 and Ev2 recorded vertical eye movements)- 5 EMG channels (M1 - chin EMG, FlP-FlD - a bipolar channel recording EMG from left arm flexor digitorum profundus muscle, FrP-FrD - a bipolar channel recording EMG from right arm flexor digitorum profundus muscle, DlP-DlD - a bipolar channel recording EMG from left arm deltoid muscle, DrP-DrD - a bipolar channel recording EMG from right deltoid muscle) - EDF files may contain an additional STATUS channel with a boundary event, that was automatically created by EEGlab when cutting files. As this event has no meaning, the STATUS channel can be ignored/deleted.#### Electrophysiological recordings ####<br>To record EEG activity, 16 electrodes (Fp1, Fp2, F7, F3, Fz, F4, F8, T3, T4, T5, P3, Pz, P4, T6, O1, O2) were placed on the scalp following the standard 10–20 system (Jasper, 1958). C3, Cz and C4 electrode locations were left empty for the placement of tDCS electrodes. To record eye blinks and vertical saccades, two electrooculography (EOG) electrodes were placed below and above the left eye, while two other electrodes placed adjacent to the lateral canthi of each eye were used to measure horizontal saccades. An electromyography (EMG) electrode placed on the chin was used to record muscle tone, which was used for the scoring of sleep stages. The reference for all these electrodes was placed on the right ear mastoid and the ground electrode was placed on the temple. In addition, two bipolar EMG channels were used to record muscle activity in the right and the left arm flexor digitorum profundus, which were later used to analyze peripheral motor activity. Another two EMG channels recorded activity of the deltoid muscles in both arms. Electrophysiological recordings were continuously monitored on a computer screen and all electrodes were regularly checked throughout the night to ensure that the impedance remained under 5 kΩ. All data were recorded at 500 Hz sampling rate with Ag/AgCl electrodes using NeuroScan amplifier SynAmps Model 5083. Given that tDCS onset induces a slow frequency artifact in the EEG that may preclude online polysomnographic scoring, a 1-Hz high-pass filter was applied during recording for online monitoring of sleep stages (Marshall et al., 2004). As expected, tDCS onset- and offset-induced artifacts always faded away after 5–10 sec.<br>### Data acquisition ###<br>#### Collection of dream reports ####<br>Based on previous research of tDCS over the motor cortex (Nitsche et al., 2000), we expected the stimulation effects to last for at least one minute, providing a window of tDCS-artefact-free electrophysiological data. Thus, one minute after the termination of tDCS or sham-stimulation, participants were awakened from REM sleep with a standard awakening tone. They were then asked to give a verbal report of “everything that was going on in your mind before awakening”, aiming to facilitate dream recall. Afterwards, participants were asked if they remembered anything else about their dream. To avoid a possible bias between stimulation conditions, these questions were played from a pre-recorded computer audio file.Following the free dream report, participants were asked to fill in the BED Questionnaire. The questionnaire was designed as an internet survey programmed on www.webropol.com and was projected on a screen above the bed in the sleep laboratory. The monitor was on a flexibly moving arm and could easily be moved into a comfortable position, enabling participants to navigate and respond to the BED Questionnaire by controlling a mouse while lying in bed. To answer the questions with an open format, participants used a keyboard that was placed nearby.Participants were stimulated and awakened two or three times per night, depending on how many REM sleep periods they had. The number of awakenings was balanced across the first and the second night and across the two stimulation conditions. White dream reports (i.e. cases when a person reports the occurrence of dream experiences but cannot recall any specific details) as well as sleep mentation reports (i.e. when a person reports non-perceptual subjective experiences, such as thinking) were excluded from the analysis. Two white dream and three sleep mentation reports, reported by five different participants, were excluded, as well as the answers to the BED Questionnaire (see above) collected after these verbal reports. All excluded reports were collected after the first awakening, and four of them after sham-stimulation. A total of 50 dreams reported during a total of 20 nights were available for analyses.<br>### Data preprocessing ###<br>Recordings provide raw data.<br>