| 1. |
- Bergman, Monica, et al.
(författare)
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Dangerous Waters : The Impact of the 2004 Indian Ocean Tsunami on Survivor Dream Content
- 2023
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Ingår i: Dreaming (New York, N.Y.). - : American Psychological Association (APA). - 1053-0797 .- 1573-3351. ; 33:4, s. 369-387
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Tidskriftsartikel (refereegranskat)abstract
- Episodic memories of emotionally salient and personally significant events are often incorporated into dreams, although rarely replayed identically to the original waking event except in replicative posttraumatic nightmares. We investigated, in five Swedish female 2004 Indian Ocean tsunami survivors, how episodic memories of the catastrophe were reflected in their dreams after trauma, both in retrospectively recalled nightmares and bad dreams, and in prospective dream diaries completed several months after the catastrophe. We also assessed whether the emotional and threatening dream content differed between the trauma and a matched control group. Based on the threat simulation theory, we predicted that the trauma group dreams would portray notable similarities with elements related to the original tsunami trauma, and that the trauma group would demonstrate a higher prevalence of negative emotional states, and a higher frequency of threatening dream events as well as more severe threats in their dreams. Only the first hypothesis was partially supported, with retrospective nightmares bearing higher similarity to the trauma experience than the prospective dream diary dreams. However, we observed no statistically significant differences in emotional or threatening dream content between the groups, suggesting that the trauma group participants were not suffering from significant posttraumatic dreaming at the time of systematic dream data collection. Yet, specific features of the trauma group dreams might be interpreted as remnants of episodic tsunami-related memories: Their dreams had a higher percentage of life-threatening events depicting realistic but improbable threats, and an analysis of water-related themes evidenced stressful themes related to waves.
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| 2. |
- Bergman, Monica, et al.
(författare)
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The Holocaust as a Lifelong Nightmare : Posttraumatic Symptoms and Dream Content in Polish Auschwitz Survivors 30 Years After World War II
- 2020
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Ingår i: American Journal of Psychology. - : University of Illinois Press. - 0002-9556 .- 1939-8298. ; 133:2, s. 143-167
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Tidskriftsartikel (refereegranskat)abstract
- Posttraumatic symptoms, including nightmares, are more prevalent in World War II survivors than in the general population, but how war experiences have affected subsequent dream content in specific survivor populations remains less explored. In the present study, we used self -reports collected in 1973 from Polish Auschwitz survivors (N = 150; 45 women) to investigate the prevalence of posttraumatic symptoms, classified according to the DSM-5 diagnostic criteria for posttraumatic stress disorder (PTSD). Furthermore, we classified main themes, central emotions, and threatening events in the dreams (N = 632) of the survivors, comparing dreams recalled from before, during, and after the war. Of the respondents, 12.7% described experiencing all diagnostic criteria for PTSD. War-related themes were less common in dreams dreamt before than during the war but were most common after the war. Themes related to family and freedom were most likely to appear in dreams dreamt during than before or after the war. The most often occurring emotion was fear, and dreams from after the war were likely to contain more negative and less positive emotions than dreams dreamt during the war. The likelihoods of reporting threatening events and threats involving aggression were higher in dreams dreamt during than before the war and in dreams dreamt after than during the war. In conclusion, PTSD symptoms were common in Polish Auschwitz survivors 30 years after World War II, and the themes, emotions, and threatening events in their dreams seem to reflect lifelong posttraumatic dreaming. We interpret the results as lending support for the threat simulation theory of dreaming.
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| 3. |
- Filimonov, Dmitri, et al.
(författare)
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Modality-specific and modality-general electrophysiological correlates of visual and auditory awareness : Evidence from a bimodal ERP experiment
- 2022
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Ingår i: Neuropsychologia. - : Elsevier. - 0028-3932 .- 1873-3514. ; 166
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Tidskriftsartikel (refereegranskat)abstract
- To date, most studies on the event-related potential (ERP) correlates of conscious perception have examined a single perceptual modality. We compared electrophysiological correlates of visual and auditory awareness in the same experiment to test whether there are modality-specific and modality-general correlates of conscious perception. We used near threshold stimulation and analyzed event-related potentials in response to aware and unaware trials in visual, auditory and bimodal conditions. The results showed modality-specific negative amplitude correlates of conscious perception between 200 and 300 ms after stimulus onset. A combination of these auditory and visual awareness negativities was observed in the bimodal condition. A later positive amplitude difference, whose early part was modality-specific, possibly reflecting access to global workspace, and later part shared modality-general features, possibly indicating higher level cognitive processing involving the decision making, was also observed.
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| 4. |
- Förster, Jona, et al.
(författare)
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ERP and MEG correlates of visual consciousness : The second decade
- 2020
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Ingår i: Consciousness and Cognition. - : Elsevier. - 1053-8100 .- 1090-2376. ; 80
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Tidskriftsartikel (refereegranskat)abstract
- The first decade of event-related potential (ERP) research had established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a posterior negative component in the N2 time range, and the late positivity (LP), an anterior positive component in the P3 time range. Two earlier extensive reviews ten years ago had concluded that VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas LP probably reflects later processes associated with reflective/access consciousness. This article provides an update to those earlier reviews. ERP and MEG studies that have appeared since 2010 and directly compared ERPs between aware and unaware conditions are reviewed, and important new developments in the field are discussed. The result corroborates VAN as the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on LP as an ERP correlate of phenomenal consciousness.
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| 5. |
- Grassini, Simone, et al.
(författare)
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Processing of natural scenery is associated with lower attentional and cognitive load compared with urban ones
- 2019
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Ingår i: Journal of Environmental Psychology. - : Academic Press. - 0272-4944 .- 1522-9610. ; 62, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Environmental psychology has provided evidence for psychologically favorable effects of exposure to natural settings, by means of controlled laboratory experiments as well as outdoor field studies. Most of these studies have employed subjective rating scales to assess processes and outcomes of exposure to nature, while only few of them have used physiological measures to assess the neural correlates of these benefits. The present study used electroencephalography (EEG) to explore how the brain engages in processing of images of natural vs. urban scenery. During EEG recording, the participants (n = 32) were presented with a series of photos depicting urban or natural scenery. Participants rated the sceneries for their subjective relaxing value. Images of natural scenery were rated as more relaxing compared to the images of urban scenery. Event related potentials suggested a lower attentional demand for images of natural scenery compared to urban ones. Signal spectral analyses revealed differences in brain activity level and cognitive demand between natural and urban scenery. Our data suggest that the visual perception of natural environments calls for less attentional and cognitive processing, compared with urban ones. © 2019 Elsevier Ltd
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| 6. |
- Grassini, Simone, et al.
(författare)
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Subjective ratings of fear are associated with frontal late positive potential asymmetry, but not with early brain activity over the occipital and centro-parietal cortices
- 2020
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Ingår i: Psychophysiology. - : John Wiley & Sons. - 0048-5772 .- 1469-8986. ; 57:12
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Tidskriftsartikel (refereegranskat)abstract
- The human frontal cortex is asymmetrically involved in motivational and affective processing. Several studies have shown that the left-frontal hemisphere is related to positive and approach-related affect, whereas the right-frontal hemisphere is related to negative and withdrawal-related affect. The present study aimed to investigate whether evolutionarily threatening stimuli modulate asymmetrical frontal activity. We examined hemispheric differences in frontal late positive potentials (f-LPP asymmetry) and frontal alpha power activation (frontal alpha asymmetry, FAA) in response to images depicting snakes, spiders, butterflies, and birds. Results showed that the late component of f-LPP asymmetry, but not FAA, was modulated by the category of stimuli. Specifically, threatening stimuli (snakes and spiders) evoked a relatively large late f-LPP over the right-frontal hemisphere than non-threatening stimuli (birds and butterflies). Moreover, this relatively great right-frontal activity was positively associated with the subjective ratings of fear. Importantly, the subjective ratings of fear were not associated with early brain activity over the occipital or centro-parietal cortices. These results suggest that late f-LPP asymmetry may reflect higher order affective processes, specifically the subjective appraisal of threatening stimuli and the subjective experience of fear, that are independent of the fast and automatic processing of evolutionarily significant and affectively arousing stimuli.
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| 7. |
- Hurme, Mikko, et al.
(författare)
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V1 activity during feedforward and early feedback processing is necessary for both conscious and unconscious motion perception
- 2019
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Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 185, s. 313-321
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Tidskriftsartikel (refereegranskat)abstract
- The study of blindsight has revealed a seminal dissociation between conscious vision and visually guided behavior: some patients who are blind due to V1 lesions seem to be able to employ unconscious visual information in their behavior. The standard assumption is that these findings generalize to the neurologically healthy. We tested whether unconscious processing of motion is possible without the contribution of V1 in neurologically healthy participants by disturbing activity in V1 using transcranial magnetic stimulation (TMS). Unconscious processing was measured with redundant target effect (RTE), a phenomenon where participants respond faster to two stimuli than to one stimulus, when the task is just to respond as fast as possible when one stimulus or two simultaneous stimuli are presented. We measured the RTE caused by a motion stimulus. V1 activity was interfered with different stimulus onset asynchronies (SOA) to test whether TMS delivered in a specific time window suppresses conscious perception (participant reports seeing only one of the two stimuli) but does not affect unconscious processing (RTE). We observed that at each SOA, when TMS suppressed conscious perception of the stimulus, the RTE was also eliminated. However, when visibility of the redundant target was suppressed with a visual mask, we found unconscious processing of motion. This suggests that unconscious processing of motion depends on V1 in neurologically healthy humans. We conclude that the neural mechanisms that enable motion processing in blindsight are modulated by neuroplastic changes in connectivity between subcortical areas and the visual cortex after the V1 lesion. Neurologically healthy observers cannot process motion unconsciously without functioning of V1.
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| 8. |
- Intaite, Monika, et al.
(författare)
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Perceptual reversals of Necker stimuli during intermittent presentation with limited attentional resources
- 2013
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Ingår i: Psychophysiology. - : Wiley-Blackwell. - 0048-5772 .- 1469-8986. ; 50:1, s. 82-96
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Tidskriftsartikel (refereegranskat)abstract
- During prolonged viewing of ambiguous stimuli, such as Necker cubes, sudden perceptual reversals occur from one perceptual interpretation to another. The role of attention in such reversals is not clear. We tested whether perceptual reversals depend on attentional resources by manipulating perceptual load and recording event-related potentials (ERPs) during intermittent presentation of Necker stimuli. The results did not reveal any influence for perceptual load on the frequency of reversals. The ERPs showed that perceptual load influenced electrophysiological activity over parieto-central areas in the P1 time window (110–140 ms), but load did not modify the early enhancements of positivity (30–140 ms), which correlated with perceptual reversals at occipito-temporal sites. We conclude that disambiguation of ambiguous figures is based on early mechanisms that can work efficiently with only a minimal amount of attentional resources.
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| 9. |
- Koivisto, Mika, et al.
(författare)
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Different Electrophysiological Correlates of Visual Awareness for Detection and Identification
- 2017
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Ingår i: Journal of cognitive neuroscience. - : MIT Press. - 0898-929X .- 1530-8898. ; 29:9, s. 1621-1631
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Tidskriftsartikel (refereegranskat)abstract
- Detecting the presence of an object is a different process than identifying the object as a particular object. This difference has not been taken into account in designing experiments on the neural correlates of consciousness. We compared the electrophysiological correlates of conscious detection and identification directly by measuring ERPs while participants performed either a task only requiring the conscious detection of the stimulus or a higher-level task requiring its conscious identification. Behavioral results showed that, even if the stimulus was consciously detected, it was not necessarily identified. A posterior electrophysiological signature 200-300 msec after stimulus onset was sensitive for conscious detection but not for conscious identification, which correlated with a later widespread activity. Thus, we found behavioral and neural evidence for elementary visual experiences, which are not yet enriched with higher-level knowledge. The search for the mechanisms of consciousness should focus on the early elementary phenomenal experiences to avoid the confounding effects of higher-level processes.
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| 10. |
- Koivisto, Mika, et al.
(författare)
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Recurrent processing enhances visual awareness but is not necessary for fast categorization of natural scenes
- 2014
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Ingår i: Journal of cognitive neuroscience. - : MIT Press. - 0898-929X .- 1530-8898. ; 26:2, s. 223-231
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Tidskriftsartikel (refereegranskat)abstract
- Humans are rapid in categorizing natural scenes. Electrophysiological recordings reveal that scenes containing animals can be categorized within 150 msec, which has been interpreted to indicate that feedforward flow of information from V1 to higher visual areas is sufficient for visual categorization. However, recent studies suggest that recurrent interactions between higher and lower levels in the visual hierarchy may also be involved in categorization. To clarify the role of recurrent processing in scene categorization, we recorded EEG and manipulated recurrent processing with object substitution masking while the participants performed a go/no-go animal/nonanimal categorization task. The quality of visual awareness was measured with a perceptual awareness scale after each trial. Masking reduced the clarity of perceptual awareness, slowed down categorization speed for scenes that were not clearly perceived, and reduced the electrophysiological difference elicited by animal and nonanimal scenes after 150 msec. The results imply that recurrent processes enhance the resolution of conscious representations and thus support categorization of stimuli that are difficult to categorize on the basis of the coarse feedforward representations alone.
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