| 1. |
- Eklund, Rasmus, et al.
(författare)
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Auditory awareness negativity is an electrophysiological correlate of awareness in an auditory threshold task
- 2019
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Ingår i: Consciousness and Cognition. - : Elsevier BV. - 1053-8100 .- 1090-2376. ; 71, s. 70-78
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Tidskriftsartikel (refereegranskat)abstract
- One theory of visual awareness proposes that electrophysiological activity related to awareness occurs in primary visual areas approximately 200 ms after stimulus onset (visual awareness negativity: VAN) and in fronto-parietal areas about 300 ms after stimulus onset (late positivity: LP). Although similar processes might be involved in auditory awareness, only sparse evidence exists for this idea. In the present study, we recorded electrophysiological activity while subjects listened to tones that were presented at their own awareness threshold. The difference in electrophysiological activity elicited by tones that subjects reported being aware of versus unaware of showed an early negativity about 200 ms and a late positivity about 300 ms after stimulus onset. These results closely match those found in vision and provide convincing evidence for an early negativity (auditory awareness negativity: AAN), as well as an LP. These findings suggest that theories of visual awareness are also applicable to auditory awareness.
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| 2. |
- Eklund, Rasmus, et al.
(författare)
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Effects of a Manual Response Requirement on Early and Late Correlates of Auditory Awareness
- 2019
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- In hearing, two neural correlates of awareness are the auditory awareness negativity (AAN) and the late positivity (LP). These correlates of auditory awareness are typically observed with tasks in which subjects are required to report their awareness with manual responses. Thus, the correlates may be confounded by this manual response requirement. We manipulated the response requirement in a tone detection task (N = 52). Tones were presented at each subject’s individual awareness threshold while high-density electroencephalography (EEG) activity was recorded. In one response condition, subjects pushed a button if they were aware of the tone and withheld responding if they were unaware of the tone. In the other condition, subjects pushed a button if they were unaware of the tone and withheld responding if they were aware of the tone. To capture AAN and LP, difference waves were computed between aware and unaware trials, separately for trials in which responses were required and trials in which responses were not required. Results suggest that AAN and LP are unaffected by the response requirement. These findings imply that in hearing, early and late correlates of awareness are not confounded by a manual response requirement. Furthermore, the results suggest that AAN originates from bilateral auditory cortices, supporting the view that AAN is a neural correlate of localized recurrent processing in early sensory areas.
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| 3. |
- Eklund, Rasmus, 1989-
(författare)
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Electrophysiological correlates of consciousness
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- How does the brain enable us to experience seeing or hearing a stimulus? If a stimulus is repeatedly presented at the awareness threshold, subjects will report that they are aware of the stimulus on half of the presentations. Electroencephalography (EEG) can be used to non-invasively record neural activity as event-related potentials (ERPs). The contrastive analysis of neural activity to trials rated as aware minus neural activity to trials rated as unaware reveals the neural correlates of consciousness (NCC). Research on the NCC in vision has resulted in two ERPs: an early negative difference wave (visual awareness negativity, VAN) and a subsequent late positivity (LP). Visual awareness may be reflected by one or both of these ERPs. However, the contrastive analysis (aware minus unaware) may not isolate the NCC because it arguably compares aware processing with a combination of unaware processing and no processing. In support, previous research that tried to isolate a comparison between aware processing and unaware processing found that LP was the only NCC. However, subsequent replications suggested VAN and LP as NCC. Because of these mixed results, we followed up on these studies in Study I with a preregistered design that manipulated stimulus size. Results showed VAN and LP as NCC. The findings provide evidence for VAN as an early NCC.Another main goal of this thesis was to investigate auditory awareness. In Study II, an auditory threshold task was used, and the contrastive analysis revealed an early negative difference wave (auditory awareness negativity, AAN) and LP. These ERPs are comparable to VAN and LP in vision. Because post-perceptual processes related to responding may confound the NCC in contrastive analysis, no-response tasks can be used to isolate awareness-related activity. In vision, a previous study in which the manual response requirement was manipulated showed effects on LP but not on VAN. In Study III, we used a similar task with auditory stimuli at the awareness threshold. Results suggested that AAN and LP are unaffected by the response manipulation. However, the present no-response task may not be optimal for removing post-perceptual processing because subjects need to reflect on their experience even if they do not need to respond manually. Additional analyses that attempted source localization of the AAN suggested that it is generated in auditory cortex.From a theoretical perspective, one view of these results is that VAN and AAN reflect local recurrent processing and that this is the neural signature of awareness, whereas LP reflects global recurrent processing that enables reporting. Other views suggest that VAN and AAN merely reflect preconscious processes, whereas LP and global recurrent processing reflect consciousness. The studies described in this thesis do not support one theory over the other but provide robust evidence for early neural correlates of visual and auditory awareness.
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| 4. |
- Eklund, Rasmus, et al.
(författare)
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Is auditory awareness negativity confounded by performance?
- 2020
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Ingår i: Consciousness and Cognition. - : Elsevier BV. - 1053-8100 .- 1090-2376. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- Research suggests that the electrophysiological correlates of consciousness are similar in hearing as in vision: the auditory awareness negativity (AAN) and the late positivity (LP). However, from a recently proposed signal-detection perspective, these correlates may be confounded by performance, as the strength of the internal responses differs between aware and unaware trials. Here, we tried to apply this signal-detection approach to correct for performance in an auditory discrimination and detection task (N = 28). A large proportion of subjects had to be excluded because even a small response bias distorted the correction. For the remaining subjects, the correction mainly increased noise in the measurement. Furthermore, the signal-detection approach is theoretically problematic because it may isolate post-perceptual processes and eliminate awareness-related activity. Therefore, we conclude that AAN and LP are not confounded by performance and that the contrastive analysis identifies both as correlates of awareness.
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| 5. |
- Eklund, Rasmus, et al.
(författare)
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The early but not the late neural correlate of auditory awareness reflects lateralized experiences
- 2021
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Ingår i: Neuropsychologia. - : Elsevier BV. - 0028-3932 .- 1873-3514. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- Theories disagree as to whether it is the early or the late neural correlate of awareness that plays a critical role in phenomenal awareness. According to recurrent processing theory, early activity in primary sensory areas corresponds closely to phenomenal awareness. In support, research with electroencephalography found that in the visual and somatosensory modality, an early neural correlate of awareness is contralateral to the perceived side of stimulation. Thus, early activity is sensitive to the perceived side of visual and somatosensory stimulation. Critically, it is unresolved whether this is true also for hearing. In the present study (N = 26 students), Bayesian analyses showed that the early neural correlate of awareness (auditory awareness negativity, AAN) was stronger for contralateral than ipsilateral electrodes whereas the late correlate of auditory awareness (late positivity, LP) was not lateralized. These findings demonstrate that the early but not the late neural correlate of auditory awareness reflects lateralized experiences. Thus, these findings imply that AAN is a more suitable NCC than LP because it correlates more closely with lateralized experiences.
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| 6. |
- Eklund, Rasmus, et al.
(författare)
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Visual awareness negativity is an early neural correlate of awareness : A preregistered study with two Gabor sizes
- 2018
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Ingår i: Cognitive, Affective, & Behavioral Neuroscience. - : Springer Science and Business Media LLC. - 1530-7026 .- 1531-135X. ; 18:1, s. 176-188
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Tidskriftsartikel (refereegranskat)abstract
- Electrophysiological recordings are commonly used to study the neural correlates of consciousness in humans. Previous research is inconsistent as to whether awareness can be indexed with visual awareness negativity (VAN) at about 200 ms or if it occurs later. The present study was preregistered with two main aims: First, to provide independent evidence for or against the presence of VAN, and second, to study whether stimulus size may account for the inconsistent findings. Subjects were shown low-contrast Gaussian filtered gratings (Gabor patches) in the four visual quadrants. Gabor size (large and small) was varied in different sessions and calibrated to each subject’s threshold of visual awareness. Event-related potentials were derived from trials in which subjects localized the Gabors correctly to capture the difference between trials in which they reported awareness versus no awareness. Bayesian analyses revealed very strong evidence for the presence of VAN for both Gabor sizes. However, there was no evidence for or against an effect of stimulus size. The present findings provide evidence for VAN as an early neural correlate of awareness.
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| 7. |
- Eklund, Veronica, et al.
(författare)
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Fiskenäringen : Uppdatering av bränsleförbrukning samt emissionsfaktorer
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fiskeflottans bränsleförbrukning undersöks endast intermittent av Energimyndigheten och senast för 2017. För åren mellan undersökningarna har Energimyndigheten använt antal arbetade timmar i fiskesektorn (inklusive arbetade timmar i land) för att skriva fram bränsleförbrukningen, medan SMED har använt fiskeflottans installerade effekt som framskrivningsmetod för att beräkna utsläpp från fiskeflottan till inventeringen. Dessa två metoder, som ger olika resultat, har i denna studie jämförts med varandra samt andra alternativ till att skriva fram bränsleförbrukningen. Branschorganisationen Swedish Pelagic Federation (SPF) anser att antal dagar till sjöss troligen är den mest pålitliga framskrivningsmetoden och den korrelerar även väl med SMED:s framskrivningsmetod.Under projektets gång framkom det att HaV årligen samlar in uppgifter om fiskeflottans bränsleförbrukning. Det bästa skulle vara om SMED kunde använda dessa data direkt och på så sätt undvika framskrivning helt. Dessa data anses dock inte vara av användbar kvalitet i dagsläget, men förhoppningsvis kommer detta vara fallet till submission 2023. SMED och Naturvårdsverket bör istället komma överens om vilken framskrivning som bör användas i årets submission.Vid projektets början antogs att det huvudsakliga bränslet för fiskeflottan var en skattebefriad MK1-diesel. Under samtal med leverantörer av bränslen till fiskeflottan framkom att fiskefartyg framförallt använder Eldningsolja 1 (EO1), som även benämns gasolja eller Marine Gas Oil (MGO). Detta är samma bränsle som används för uppvärmning av villor, men när det används för framdrivning av fartyg kallas det för diesel och när det används för uppvärmning av villor kallas det för E10/E32. I samtalen med bränsleleverantörerna kom det även fram att bränslet som levereras till fiskefartyg aldrig innehåller en inblandning av biobränsle. SMED rekommenderar därför att fiskets bränsle ändras från diesel till EO1 i inventeringen och att man inte tar med en inblandning av biobränsle för fiskesektorn.Inom ramen för detta projekt har även emissionsfaktorerna för NOX, CO2 och SO2 uppdaterats, vilka var de enda som var möjliga att uppdatera med det dataunderlag som fanns tillgängligt. I framtiden bör man samköra uppdatering av de emissionsfaktorer som används av SMED inom mobila sektorn när samma bränslen används och motivera varför de skiljer sig åt i de fall där så är fallet. När man uppdaterar emissionsfaktorer för EO1/MGO bör SO2, CO2 och metaller för bränsle inom fiskeflottan och sjöfarten (inrikes EO1/MGO) uppdateras samtidigt, eftersom dessa sektorer använder samma typ av bränsle. För metaller har ett arbete påbörjats med att identifiera brister i de emissionsfaktorer som används idag.
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| 8. |
- Ried, Janina S., et al.
(författare)
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A principal component meta-analysis on multiple anthropometric traits identifies novel loci for body shape
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Large consortia have revealed hundreds of genetic loci associated with anthropometric traits, one trait at a time. We examined whether genetic variants affect body shape as a composite phenotype that is represented by a combination of anthropometric traits. We developed an approach that calculates averaged PCs (AvPCs) representing body shape derived from six anthropometric traits (body mass index, height, weight, waist and hip circumference, waist-to-hip ratio). The first four AvPCs explain >99% of the variability, are heritable, and associate with cardiometabolic outcomes. We performed genome-wide association analyses for each body shape composite phenotype across 65 studies and meta-analysed summary statistics. We identify six novel loci: LEMD2 and CD47 for AvPC1, RPS6KA5/C14orf159 and GANAB for AvPC3, and ARL15 and ANP32 for AvPC4. Our findings highlight the value of using multiple traits to define complex phenotypes for discovery, which are not captured by single-trait analyses, and may shed light onto new pathways.
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| 9. |
- Szychowska, Malina, et al.
(författare)
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Effects of sound pressure level and visual perceptual load on the auditory mismatch negativity
- 2017
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 640, s. 37-41
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Tidskriftsartikel (refereegranskat)abstract
- Auditory change detection has been studied extensively with mismatch negativity (MMN), an event-related potential. Because it is unresolved if the duration MMN depends on sound pressure level (SPL), we studied effects of different SPLs (56, 66, and 76 dB) on the duration MMN. Further, previous research suggests that the MMN is reduced by a concurrent visual task. Because a recent behavioral study found that high visual perceptual load strongly reduced detection sensitivity to irrelevant sounds, we studied if the duration MMN is reduced by load, and if this reduction is stronger at low SPLs. Although a duration MMN was observed for all SPLs, the MMN was apparently not moderated strongly by SPL, perceptual load, or their interaction, because all 95% CIs overlapped zero. In a contrast analysis of the MMN (across loads) between the 56-dB and 76-dB groups, evidence (BF = 0.31) favored the null hypothesis that duration MMN is unaffected by a 20-dB increase in SPL. Similarly, evidence (BF = 0.19) favored the null hypothesis that effects of perceptual load on the duration MMN do not change with a 20-dB increase in SPL. However, evidence (BF = 3.12) favored the alternative hypothesis that the effect of perceptual load in the present study resembled the overall effect in a recent meta-analysis. When the present findings were combined with the meta-analysis, the effect of load (low minus high) was −0.43 μV, 95% CI [−0.64, −0.22] suggesting that the duration MMN decreases with load. These findings provide support for a sensitive monitoring system of the auditory environment.
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| 10. |
- Wiens, Stefan, et al.
(författare)
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Cascade and no-repetition rules are comparable controls for the auditory frequency mismatch negativity in oddball tasks
- 2019
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Ingår i: Psychophysiology. - : Wiley. - 0048-5772 .- 1469-8986. ; 56:1
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Tidskriftsartikel (refereegranskat)abstract
- The mismatch negativity (MMN) has been widely studied with oddball tasks to index processing of unexpected auditory change. The MMN is computed as the difference of deviant minus standard and is used to capture the pattern violation by the deviant. However, this oddball MMN is confounded because the deviant differs physically from the standard and is presented less often. To improve measurement, the same tone as the deviant is presented in a separate condition. This control tone is equiprobable with other tones and is used to compute a corrected MMN (deviant minus control). Typically, the tones are in random order except that consecutive tones are not identical (no-repetition rule). In contrast, a recent study on frequency MMN presented tones in a regular up-and-down sequence (cascade rule). If the cascade rule is detected more easily than the no-repetition rule, there should be a lower risk of a confounding MMN within the cascade condition. However, in previous research, the cascade and no-repetition conditions differed not only in the regularity of the tone sequence but also in number of tones, frequency range, and proportion of tones. We controlled for these differences to isolate effects of regularity in the tone sequence. Results of our preregistered analyses provided moderate evidence (BF01>6) that the corrected MMN did not differ between cascade and no-repetition conditions. These findings imply that no-repetition and cascade rules are processed similarly and that the no-repetition condition provides an adequate control in frequency MMN.
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