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- Ahmed, B, et al.
(författare)
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Cortical dynamics subserving visual apparent motion
- 2008
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Ingår i: Cerebral cortex (New York, N.Y. : 1991). - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 18:12, s. 2796-2810
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Boyle, Julie A., et al.
(författare)
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The Human Brain Distinguishes between Single Odorants and Binary Mixtures
- 2009
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 19:1, s. 66-71
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Tidskriftsartikel (refereegranskat)abstract
- Single odors are processed differently from odor mixtures in the cortex of rodents. We investigated whether single and binary odor mixtures activate different regions also in the human brain. We analyzed data from positron emission tomography scans using pyridine, citral, and 5 mixtures of pyridine and citral in proportions varying from 10/90 to 90/10, with 50/50 being the most impure. Comparing mixtures with single odorants gave activation in the left cingulate and right parietal and superior frontal cortices and bilateral activation in the anterior and lateral orbitofrontal cortices. We also found that brain activity in the lateral orbitofrontal cortex (OFC) increased with odorant impurity, whereas the anterior OFC was activated for binary odor mixtures and deactivated for single components. We conclude that binary odor mixtures and their individual components are processed differently by the human brain. The lateral portion of the OFC responds to mixture impurity in a graded fashion, whereas the anterior portion acts like an on-off detector of odor mixtures.
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| 10. |
- Eriksson, Johan, et al.
(författare)
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Similar frontal and distinct posterior cortical regions mediate visual and auditory perceptual awareness
- 2007
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 17:4, s. 760-765
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Tidskriftsartikel (refereegranskat)abstract
- Activity in ventral visual cortex is a consistent neural correlate of visual consciousness. However, activity in this area seems insufficient to produce awareness without additional involvement of frontoparietal regions. To test the generality of the frontoparietal response, neural correlates of auditory awareness were investigated in a paradigm that previously has revealed frontoparietal activity during conscious visual perception. A within-experiment comparison showed that frontal regions were related to both visual and auditory awareness, whereas parietal activity was correlated with visual awareness and superior temporal activity with auditory awareness. These results indicate that frontal regions interact with specific posterior regions to produce awareness in different sensory modalities.
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| 13. |
- Habib, Reza, et al.
(författare)
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Neural Correlates of Availability and Accessibility in Memory
- 2008
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 8:7, s. 1720-1726
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Failure to remember can be due to not having information available in memory or to an inability to access information that is available. We used functional magnetic resonance imaging to examine brain responses during encoding and successive cued recall and associative recognition tests of paired associates. Items were classified into 3 categories based on performance on the 2 retrieval tests: 1) successfully remembered (both recalled and recognized), 2) inaccessible (not recalled but later recognized), and 3) forgotten (neither recalled nor recognized). During cued recall, availability in memory was signaled in a network of regions including bilateral medial temporal lobe, left middle temporal cortex, and the parietal cortex. Memory access resulted in heightened activity in these regions as well as in left inferior frontal cortex. Encoding-related activity in hippocampus and inferior temporal cortex predicted subsequent availability and left inferior frontal activity predicted subsequent access. These results suggest that failure to access information that is available in memory may reflect weaker memory representations.
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| 15. |
- Johansson, Mikael, et al.
(författare)
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When remembering causes forgetting: Electrophysiological correlates of retrieval-induced forgetting
- 2007
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 17:6, s. 1335-1341
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Tidskriftsartikel (refereegranskat)abstract
- People tend to forget information that is related to memories they are actively trying to retrieve. On the basis of results from behavioral studies, such retrieval-induced forgetting is held to result from inhibitory control processes that are recruited to attenuate interference caused by competing memory traces. Employing electrophysiological measures of brain activity, the present study examined the neural correlates of these inhibitory processes as they operate. The results demonstrate that sustained prefrontal event-related potentials were 1) related to whether or not selective memory retrieval was required during reprocessing of previously studied words and 2) predictive of individual differences in the amount of forgetting observed in an ensuing recall test. The present findings give support to an inhibitory control account of retrieval-induced forgetting and are in accord with the view that prefrontal regions play an important role in the selection and maintenance of relevant memory representations at the expense of those currently irrelevant.
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| 17. |
- Kokaia, Zaal, et al.
(författare)
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Regulation of stroke-induced neurogenesis in adult brain--recent scientific progress.
- 2006
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 16, s. 162-167
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Tidskriftsartikel (refereegranskat)abstract
- Stroke induced by middle cerebral artery occlusion in adult rodents induces the formation of new neurons in the damaged striatum, a region that normally does not show neurogenesis. Here we describe recent findings on the regulation of neurogenesis after stroke, in particular regarding the duration of the neurogenic response and the influence of age, as well as the molecular mechanisms influencing migration and survival of the new neurons. We also discuss some crucial issues that need to be addressed in the further exploration of this potential self-repair mechanism after damage to the adult brain.
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| 20. |
- Makuuchi, M
(författare)
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Is Broca's area crucial for imitation?
- 2005
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Ingår i: Cerebral cortex (New York, N.Y. : 1991). - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 15:5, s. 563-570
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Tidskriftsartikel (refereegranskat)
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| 22. |
- Olesen, Pernille, et al.
(författare)
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Brain activity related to working memory and distraction in children and adults
- 2007
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 17:5, s. 1047-1054
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Tidskriftsartikel (refereegranskat)abstract
- In order to retain information in working memory (WM) during a delay, distracting stimuli must be ignored. This important ability improves during childhood, but the neural basis for this development is not known. We measured brain activity with functional magnetic resonance imaging in adults and 13-year-old children. Data were analyzed with an event-related design to isolate activity during cue, delay, distraction, and response selection. Adults were more accurate and less distractible than children. Activity in the middle frontal gyrus and intraparietal cortex was stronger in adults than in children during the delay, when information was maintained in WM. Distraction during the delay evoked activation in parietal and occipital cortices in both adults and children. However, distraction activated frontal cortex only in children. The larger frontal activation in response to distracters presented during the delay may explain why children are more susceptible to interfering stimuli.
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| 24. |
- Persson, Jonas, 1971-, et al.
(författare)
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Structure-function correlates of cognitive decline in aging
- 2006
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 16:7, s. 907-915
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Tidskriftsartikel (refereegranskat)abstract
- To explore neural correlates of cognitive decline in aging, we used longitudinal behavioral data to identify two groups of older adults (n = 40) that differed with regard to whether their performance on tests of episodic memory remained stable or declined over a decade. Analysis of structural and diffusion tensor imaging (DTI) revealed a heterogeneous set of differences associated with cognitive decline. Manual tracing of hippocampal volume showed significant reduction in those older adults with a declining memory performance as did DTI-measured fractional anisotropy in the anterior corpus callosum. Functional magnetic resonance imaging during incidental episodic encoding revealed increased activation in left prefrontal cortex for both groups and additional right prefrontal activation for the elderly subjects with the greatest decline in memory performance. Moreover, mean DTI measures in the anterior corpus callosum correlated negatively with activation in right prefrontal cortex. These results demonstrate that cognitive decline is associated with differences in the structure as well as function of the aging brain, and suggest that increased activation is either caused by structural disruption or is a compensatory response to such disruption.
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