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Maintenance of non-consciously presented information engages the prefrontal cortex
Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
2014 (Engelska)Ingår i: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 8, s. 938-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Conscious processing is generally seen as required for flexible and willful actions, as well as for tasks that require durable information maintenance. Here we present research that questions the assumption that only consciously perceived information is durable (>500 ms). Using the attentional blink (AB) phenomenon, we rendered otherwise relatively clearly perceived letters non conscious. In a first experiment we systematically manipulated the delay between stimulus presentation and response, for the purpose of estimating the durability of non-conscious perceptual representations. For items reported not seen, we found that behavioral performance was better than chance across intervals up to 15 s. In a second experiment we used fMRI to investigate the neural correlates underlying the maintenance of non conscious perceptual representations. Critically, the relatively long delay period demonstrated in experiment 1 enabled isolation of the signal change specifically related to the maintenance period, separate from stimulus presentation and response. We found sustained BOLD signal change in the right mid-lateral prefrontal cortex, orbitofrontal cortex, and crus II of the cerebellum during maintenance of non consciously perceived information. These findings are consistent with the controversial claim that working-memory mechanisms are involved in the short-term maintenance of non-conscious perceptual representations.

Ort, förlag, år, upplaga, sidor
Frontiers Research Foundation , 2014. Vol. 8, s. 938-
Nyckelord [en]
non-conscious, durability, attention, conscious experience, perception, working memory
Nationell ämneskategori
Neurovetenskaper Psykologi
Identifikatorer
URN: urn:nbn:se:umu:diva-97212DOI: 10.3389/fnhum.2014.00938ISI: 000345132200001OAI: oai:DiVA.org:umu-97212DiVA, id: diva2:773536
Tillgänglig från: 2014-12-19 Skapad: 2014-12-12 Senast uppdaterad: 2018-06-07Bibliografiskt granskad
Ingår i avhandling
1. The neural substrates of non-conscious working memory
Öppna denna publikation i ny flik eller fönster >>The neural substrates of non-conscious working memory
2016 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Neurala substrat till icke-medvetet arbetsminne
Abstract [en]

Background: Despite our distinct impression to the contrary, we are only conscious of a fraction of all the neural activity underlying our thoughts and behavior. Most neural processes occur non-consciously, and in parallel with our conscious experience. However, it is still unclear what the limits of non-conscious processes are in terms of higher cognitive functions. Many recent studies have shown that increasingly more advanced functions can operate non-consciously, but non-conscious information is still thought to be fleeting and undetectable within 500 milliseconds. Here we used various techniques to render information non-conscious, together with functional magnetic resonance imaging (fMRI), to investigate if non-consciously presented information can be retained for several seconds, what the neural substrates of such retention are, and if it is consistent with working memory maintenance.

Results: In Study I we used an attentional blink paradigm to render stimuli (single letters) non-conscious, and a variable delay period (5 – 15 s) prior to memory test. It was found that non-conscious memory performance was above chance after all delay durations, and showed no signs of decline over time. Univariate fMRI analysis showed that the durable retention was associated with sustained BOLD signal change in the prefrontal cortex and cerebellum during the delay period. In Study II we used continuous flash suppression (CFS) to render stimuli (faces and tools) non-conscious, and a variable delay period (5 or 15 s) prior to memory test. The durable retention of up to 15 s was replicated, and it was found that stimuli identity and spatial position was retained until prospective use. In Study III we used CFS to render tools non-conscious, and a variable delay period (5 – 15 s) prior to memory test. It was found that memory performance was not better than chance. However, by using multi-voxel pattern analysis it was nonetheless possible to detect the presence vs. absence of non-conscious stimuli in the frontal cortex,and their spatial position (left vs. right) in the occipital cortex during the delay.

Conclusions: Overall these findings suggest that non-consciously presented information (identity and/or position) can be retained for several seconds,and is associated with BOLD signal in frontal and posterior regions. These findings are consistent with working memory maintenance of non-consciously presented information, and thereby constrain models of working memory and theories of consciousness.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå University, 2016. s. 99
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1835
Nyckelord
non-conscious, working memory, neural substrates, visual perception, consciousness, functional magnetic resonance imaging (fMRI)
Nationell ämneskategori
Neurovetenskaper Psykologi
Identifikatorer
urn:nbn:se:umu:diva-124808 (URN)978-91-7601-543-8 (ISBN)
Disputation
2016-09-16, Hörsal E, Humanisthuset, Umeå University, 901 87 Umeå, Sweden, Umeå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2016-08-26 Skapad: 2016-08-25 Senast uppdaterad: 2018-06-07Bibliografiskt granskad

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