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Visual consciousness: dissociating the neural correlates of perceptual transitions from sustained perception with fMRI
Umeå University, Faculty of Social Sciences, Department of Psychology.
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
Umeå University, Faculty of Social Sciences, Department of Psychology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
2004 (English)In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 13, no 1, 61-72 p.Article in journal (Refereed) Published
Abstract [en]

To investigate the possible dichotomy between the neurophysiological bases of perceptual transitions versus sustaining a particular percept over time, an fMRI study was conducted with subjects viewing fragmented pictures. Unlike most other perceptually unstable stimuli, fragmented pictures give rise to only one perceptual transition and a continuous period of sustained perception. Earlier research is inconclusive on the subject of which anatomical regions should be attributed to what temporal aspect of perception, and the aim of the present study was to shed more light on the subject. In this study occipitotemporal and fronto-parietal regions were found to be activated for both aspects. However, regions in the medial-temporal lobe were activated specifically for transitions, whereas medial and dorsolateral prefrontal regions were activated specifically for sustained perception. These results provide further support for the theory that the initial creation of perceptual awareness and upholding perceptual awareness over time are separate processes involving different brain regions.

Place, publisher, year, edition, pages
San Diego, Calif.: Academic Press , 2004. Vol. 13, no 1, 61-72 p.
National Category
Neurosciences
Identifiers
URN: urn:nbn:se:umu:diva-14902DOI: 10.1016/S1053-8100(03)00050-3PubMedID: 14990241OAI: oai:DiVA.org:umu-14902DiVA: diva2:154574
Available from: 2007-02-23 Created: 2007-02-23 Last updated: 2014-07-18Bibliographically approved
In thesis
1. The conscious brain: Empirical investigations of the neural correlates of perceptual awareness
Open this publication in new window or tab >>The conscious brain: Empirical investigations of the neural correlates of perceptual awareness
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Although consciousness has been studied since ancient time, how the brain implements consciousness is still considered a great mystery by most. This thesis investigates the neural correlates of consciousness by measuring brain activity with functional magnetic resonance imaging (fMRI) while specific contents of consciousness are defined and maintained in various experimental settings. Study 1 showed that the brain works differently when creating a new conscious percept compared to when maintaining the same percept over time. Specifically, sensory and fronto-parietal regions were activated for both conditions but with different activation patterns within these regions. This distinction between creating and maintaining a conscious percept was further supported by Study 2, which in addition showed that there are both differences and similarities in how the brain works when defining a visual compared to an auditory percept. In particular, frontal cortex was commonly activated while posterior cortical activity was modality specific. Study 3 showed that task difficulty influenced the degree of frontal and parietal cortex involvement, such that fronto-parietal activity decreased as a function of ease of identification. This is interpreted as evidence of the non-necessity of these regions for conscious perception in situations where the stimuli are distinct and apparent. Based on these results a model is proposed where sensory regions interact with controlling regions to enable conscious perception. The amount and type of required interaction depend on stimuli and task characteristics, to the extent that higher-order cortical involvement may not be required at all for easily recognizable stimuli.

Place, publisher, year, edition, pages
Umeå: Psykologi, 2007. 68 p.
Series
Umeå studies in cognitive science, ISSN 1654-2568 ; 4
Keyword
consciousness, visual perception, object identification, functional neuroimaging, top-down processing, prefrontal cortex, auditory perception
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-1430 (URN)978-91-7264-457-1 (ISBN)
Public defence
2007-12-07, MA 121, MIT-huset, Umeå Universitet, Umeå, 10:15
Opponent
Supervisors
Available from: 2007-11-13 Created: 2007-11-13 Last updated: 2011-01-27Bibliographically approved

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Eriksson, JohanLarsson, AnneRiklund Åhlström, KatrineNyberg, Lars

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Consciousness and Cognition
Neurosciences

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