| 1. |
- Móró, Levente, et al.
(författare)
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Hypnotizability, sleepiness, and subjective experience
- 2011
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Ingår i: International journal of clinical and experimental hypnosis. - : Routledge. - 0020-7144 .- 1744-5183. ; 59:2, s. 211-224
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Tidskriftsartikel (refereegranskat)abstract
- The relationships between hypnotizability, sleepiness, and the subjective experience of hypnotic suggestions were investigated in 90 participants. Scores from the Harvard Group Scale of Hypnotic Susceptibility Form A (HGSHS:A), the Karolinska Sleepiness Scale (KSS), the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index (PSQI), and our self-developed Questionnaire on Subjective Hypnotic Experiences (QSHE) were analyzed. Findings show that hypnotizability correlates with both habitual daytime sleepiness and instantaneous sleepiness after the hypnotic procedure. Results also indicate that subjective self-evaluation of responses to hypnotic suggestions may be a useful tool in some cases when comparing with other subjectively rated scales, such as those concerning sleepiness.
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| 2. |
- Noreika, Valdas, et al.
(författare)
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Consciousness lost and found : Subjective experiences in an unresponsive state
- 2011
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Ingår i: Brain and Cognition. - : Elsevier. - 0278-2626 .- 1090-2147. ; 77:3, s. 327-334
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Tidskriftsartikel (refereegranskat)abstract
- Anesthetic-induced changes in the neural activity of the brain have been recently utilized as a research model to investigate the neural mechanisms of phenomenal consciousness. However, the anesthesiologic definition of consciousness as ‘‘responsiveness to the environment’’ seems to sidestep the possibility that an unresponsive individual may have subjective experiences. The aim of the present study was to analyze subjective reports in sessions where sedation and the loss of responsiveness were induced by dexmedetomidine, propofol, sevoflurane or xenon in a nonsurgical experimental setting. After regaining responsiveness, participants recalled subjective experiences in almost 60% of sessions. During dexmedetomidine sessions, subjective experiences were associated with shallower ‘‘depth of sedation’’ as measured by an electroencephalography-derived anesthesia depth monitor. Results confirm that subjective experiences may occur during clinically defined unresponsiveness, and that studies aiming to investigate phenomenal consciousness under sedative and anesthetic effects should control the subjective state of unresponsive participants with post-recovery interviews.
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| 3. |
- Noreika, Valdas, et al.
(författare)
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Dream bizarreness and waking thought in schizophrenia
- 2010
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Ingår i: Psychiatry Research. - : Elsevier. - 0165-1781 .- 1872-7123. ; 178:3, s. 562-564
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Tidskriftsartikel (refereegranskat)abstract
- Dream diaries and reports of daytime waking thought were collected from five schizophrenia patients and matched controls. It was more difficult for blind judges to differentiate the patients' than the controls' dream reports from reports of waking thought, and patients reported shorter but more bizarre dreams than did the controls.
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| 4. |
- Noreika, Valdas, et al.
(författare)
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Early-night serial awakenings as a new paradigm for studies on NREM dreaming
- 2009
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Ingår i: International Journal of Psychophysiology. - : Elsevier. - 0167-8760 .- 1872-7697. ; 74:1, s. 14-18
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Tidskriftsartikel (refereegranskat)abstract
- A new experimental paradigm called "Early-Night Serial Awakenings" (ENSA) was explored to find out its strengths and weaknesses for psychophysiological studies of NREM sleep dreaming. Five participants spent 20 experimental nights in the sleep laboratory, and were serially awakened with approximately 24-minute intervals during Stages 2 and 3 of NREM sleep. As a total, 164 awakenings were conducted during the sessions that lasted on average 193 min. Altogether, 30% of NREM sleep awakenings led to dream reports, 39% to reports of white dreaming, and 31% to reports of dreamless sleep. Results also show that sleep EEG spectral power, dream recall frequency as well as dream complexity remained stable throughout the serial awakening sessions. We conclude that, as ENSA dreams appeared to be static and very limited in content, the paradigm we identified could be used in future studies to reveal the psychophysiological mechanisms of relatively simple forms of early-night NREM sleep dreaming. (c) 2009 Elsevier B.V. All rights reserved.
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| 5. |
- Noreika, Valdas, et al.
(författare)
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Modulating dream experience : Noninvasive brain stimulation over the sensorimotor cortex reduces dream movement
- 2020
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Ingår i: Scientific Reports. - : Springer. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Recently, cortical correlates of specific dream contents have been reported, such as the activation of the sensorimotor cortex during dreamed hand clenching. Yet, despite a close resemblance of such activation patterns to those seen during the corresponding wakeful behaviour, the causal mechanisms underlying specific dream contents remain largely elusive. Here, we aimed to investigate the causal role of the sensorimotor cortex in generating movement and bodily sensations during REM sleep dreaming. Following bihemispheric transcranial direct current stimulation (tDCS) or sham stimulation, guided by functional mapping of the primary motor cortex, naive participants were awakened from REM sleep and responded to a questionnaire on bodily sensations in dreams. Electromyographic (EMG) and electroencephalographic (EEG) recordings were used to quantify physiological changes during the preceding REM period. We found that tDCS, compared to sham stimulation, significantly decreased reports of dream movement, especially of repetitive actions. Other types of bodily experiences, such as tactile or vestibular sensations, were not affected by tDCS, confirming the specificity of stimulation effects to movement sensations. In addition, tDCS reduced EEG interhemispheric coherence in parietal areas and affected the phasic EMG correlation between both arms. These findings show that a complex temporal reorganization of the motor network co-occurred with the reduction of dream movement, revealing a link between central and peripheral motor processes and movement sensations of the dream self. tDCS over the sensorimotor cortex interferes with dream movement during REM sleep, which is consistent with a causal contribution to dream experience and has broader implications for understanding the neural basis of self-experience in dreams. © 2020, The Author(s).
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| 6. |
- Noreika, Valdas, et al.
(författare)
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Perception of Short Time Scale Intervals in a Hypnotic Virtuoso
- 2012
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Ingår i: International journal of clinical and experimental hypnosis. - : Routledge. - 0020-7144 .- 1744-5183. ; 60:3, s. 318-337
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies showed that hypnotized individuals underestimate temporal intervals in the range of several seconds to tens of minutes. However, no previous work has investigated whether duration perception is equally disorderly when shorter time intervals are probed. In this study, duration perception of a hypnotic virtuoso was tested using repeated standard temporal generalization and duration estimation tasks. When compared to the baseline state, hypnosis affected perception of intervals spread around 600 ms in the temporal generalization task but did not alter perception of slightly longer intervals spread around 1000 ms. Furthermore, generalization of temporal intervals was more orderly under hypnosis than in the baseline state. In contrast, the hypnotic virtuoso showed a typical time underestimation effect when perception of longer supra-second intervals was tested in the duration estimation task, replicating results of the previous hypnosis studies.
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| 7. |
- Salminen-Vaparanta, Niina, et al.
(författare)
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Is selective primary visual cortex stimulation achievable with TMS?
- 2012
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Ingår i: Human Brain Mapping. - : Wiley-Blackwell. - 1065-9471 .- 1097-0193. ; 33:3, s. 652-665
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Tidskriftsartikel (refereegranskat)abstract
- The primary visual cortex (V1) has been the target of stimulation in a number of transcranial magnetic stimulation (TMS) studies. In this study, we estimated the actual sites of stimulation by modeling the cortical location of the TMS-induced electric field when participants reported visual phosphenes or scotomas. First, individual retinotopic areas were identified by multifocal functional magnetic resonance imaging (mffMRI). Second, during the TMS stimulation, the cortical stimulation sites were derived from electric field modeling. When an external anatomical landmark for V1 was used (2 cm above inion), the cortical stimulation landed in various functional areas in different individuals, the dorsal V2 being the most affected area at the group level. When V1 was specifically targeted based on the individual mffMRI data, V1 could be selectively stimulated in half of the participants. In the rest, the selective stimulation of V1 was obstructed by the intermediate position of the dorsal V2. We conclude that the selective stimulation of V1 is possible only if V1 happens to be favorably located in the individual anatomy. Selective and successful targeting of TMS pulses to V1 requires MRI-navigated stimulation, selection of participants and coil positions based on detailed retinotopic maps of individual functional anatomy, and computational modeling of the TMS-induced electric field distribution in the visual cortex. It remains to be resolved whether even more selective stimulation of V1 could be achieved by adjusting the coil orientation according to sulcal orientation of the target site. Hum Brain Mapp, 2012. (C) 2011 Wiley Periodicals, Inc.
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| 8. |
- Salminen-Vaparanta, Niina, et al.
(författare)
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Neuronavigated transcranial magnetic stimulation suggests that area V2 is necessary for visual awareness
- 2012
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Ingår i: Neuropsychologia. - : Elsevier. - 0028-3932 .- 1873-3514. ; 50:7, s. 1621-1627
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Tidskriftsartikel (refereegranskat)abstract
- The primary visual cortex (V1) has been shown to be critical for visual awareness, but the importance of other low-level visual areas has remained unclear. To clarify the role of human cortical area V2 in visual awareness, we applied transcranial magnetic stimulation (TMS) over V2 while participants were carrying out a visual discrimination task and rating their subjective awareness. Individual retinotopic maps and modelling of the TMS-induced electric field in V1, V2 and V3d ensured that the electric field was at or under the phosphene threshold level in V1 and V3d, whereas in V2 it was at the higher suppressive level. As earlier shown for the V1, our results imply that also V2 is necessary for conscious visual experience. Visual awareness of stimulus presence was completely suppressed when the TMS pulse was delivered 44-84 ms after the onset of visual stimulus. Visual discrimination and awareness of stimulus features was impaired when the TMS pulse was delivered 44-104 ms after the visual stimulus onset. These results suggest that visual awareness cannot be generated without an intact V2. (C) 2012 Elsevier Ltd. All rights reserved.
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| 9. |
- Salminen-Vaparanta, Niina, et al.
(författare)
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Subjective characteristics of TMS-induced phosphenes originating in human V1 and V2
- 2014
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 24:10, s. 2751-2760
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Tidskriftsartikel (refereegranskat)abstract
- One way to study the neural correlates of visual consciousness is to localize the cortical areas whose stimulation generates subjective visual sensations, called phosphenes. While there is support for the view that the stimulation of several different visual areas in the occipital lobe may produce phosphenes, it is not clear what the contribution of each area is. Here, we studied the roles of the primary visual cortex (V1) and the adjacent area V2 in eliciting phosphenes by using functional magnetic resonance imaging-guided transcranial magnetic stimulation (TMS) combined with spherical modeling of the TMS-induced electric field. Reports of the subjective visual features of phosphenes were systematically collected and analyzed. We found that selective stimulation of V1 and V2 are equally capable of generating phosphenes, as demonstrated by comparable phosphene thresholds and similar characteristics of phosphene shape, color, and texture. However, the phosphenes induced by V1 stimulation were systematically perceived as brighter than the phosphenes induced by the stimulation of V2. Thus, these results suggest that V1 and V2 have a similar capability to produce conscious percepts. Nevertheless, V1 and V2 contribute differently to brightness: neural activation originating in V1 generates a more intense sensation of brightness than similar activation originating in V2.
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| 10. |
- Sikka, Pilleriin, et al.
(författare)
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COVID-19 on mind : Daily worry about the coronavirus is linked to negative affect experienced during mind-wandering and dreaming
- 2024
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Ingår i: Emotion. - : American Psychological Association (APA). - 1528-3542 .- 1931-1516. ; 24:1, s. 177-195
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Tidskriftsartikel (refereegranskat)abstract
- Despite a surge of studies on the effects of COVID-19 on our well-being, we know little about how the pandemic is reflected in people's spontaneous thoughts and experiences, such as mind-wandering (or daydreaming) during wakefulness and dreaming during sleep. We investigated whether and how COVID-19-related general concern, anxiety, and daily worry are associated with the daily fluctuation of the affective quality of mind-wandering and dreaming, and to what extent these associations can be explained by poor sleep quality. We used ecological momentary assessment by asking participants to rate the affect they experienced during mind-wandering and dreaming in daily logs over a 2-week period. Our preregistered analyses based on 1,755 dream logs from 172 individuals and 1,496 mind-wandering logs from 152 individuals showed that, on days when people reported higher levels of negative affect and lower levels of positive affect during mind-wandering, they experienced more worry. Only daily sleep quality was associated with affect experienced during dreaming at the within-person level: on nights with poorer sleep quality people reported experiencing more negative and less positive affect in dreams and were more likely to experience nightmares. However, at the between-person level, individuals who experienced more daily COVID-19 worry during the study period also reported experiencing more negative affect during mind-wandering and during dreaming. As such, the continuity between daily and nightly experiences seems to rely more on stable trait-like individual differences in affective processing. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
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