| 1. |
- Brandt, Christine Lycke, et al.
(author)
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Cognitive effort and schizophrenia modulate large-scale functional brain connectivity
- 2015
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In: Schizophrenia Bulletin. - 0586-7614 .- 1745-1701. ; 41:6, s. 1360-1369
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Journal article (peer-reviewed)abstract
- Schizophrenia (SZ) is characterized by cognitive dysfunction and disorganized thought, in addition to hallucinations and delusions, and is regarded a disorder of brain connectivity. Recent efforts have been made to characterize the underlying brain network organization and interactions. However, to which degree connectivity alterations in SZ vary across different levels of cognitive effort is unknown. Utilizing independent component analysis (ICA) and methods for delineating functional connectivity measures from functional magnetic resonance imaging (fMRI) data, we investigated the effects of cognitive effort, SZ and their interactions on between-network functional connectivity during 2 levels of cognitive load in a large and well-characterized sample of SZ patients (n = 99) and healthy individuals (n = 143). Cognitive load influenced a majority of the functional connections, including but not limited to fronto-parietal and default-mode networks, reflecting both decreases and increases in between-network synchronization. Reduced connectivity in SZ was identified in 2 large-scale functional connections across load conditions, with a particular involvement of an insular network. The results document an important role of interactions between insular, default-mode, and visual networks in SZ pathophysiology. The interplay between brain networks was robustly modulated by cognitive effort, but the reduced functional connectivity in SZ, primarily related to an insular network, was independent of cognitive load, indicating a relatively general brain network-level dysfunction.
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| 2. |
- Lycke Brandt, Christine, et al.
(author)
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Working memory networks and activation patterns in schizophrenia and bipolar disorder : comparison with healthy controls
- 2014
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In: British Journal of Psychiatry. - 0007-1250 .- 1472-1465. ; 204:4, s. 290-298
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Journal article (peer-reviewed)abstract
- BACKGROUND: Schizophrenia and bipolar disorder are severe mental disorders with overlapping genetic and clinical characteristics, including cognitive impairments. An important question is whether these disorders also have overlapping neuronal deficits.AIMS: To determine whether large-scale brain networks associated with working memory, as measured with functional magnetic resonance imaging (fMRI), are the same in both schizophrenia and bipolar disorder, and how they differ from those in healthy individuals.METHOD: Patients with schizophrenia (n = 100) and bipolar disorder (n = 100) and a healthy control group (n = 100) performed a 2-back working memory task while fMRI data were acquired. The imaging data were analysed using independent component analysis to extract large-scale networks of task-related activations.RESULTS: Similar working memory networks were activated in all groups. However, in three out of nine networks related to the experimental task there was a graded response difference in fMRI signal amplitudes, where patients with schizophrenia showed greater activation than those with bipolar disorder, who in turn showed more activation than healthy controls. Secondary analysis of the patient groups showed that these activation patterns were associated with history of psychosis and current elevated mood in bipolar disorder.CONCLUSIONS: The same brain networks were related to working memory in schizophrenia, bipolar disorder and controls. However, some key networks showed a graded hyperactivation in the two patient groups, in line with a continuum of neuronal abnormalities across psychotic disorders.
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| 3. |
- Brandt, Christine Lycke, et al.
(author)
-
Cognitive effort and schizophrenia modulate large-scale functional brain connectivity
- 2015
-
In: Schizophrenia Bulletin. - : Oxford University Press. - 0586-7614 .- 1745-1701. ; 41:6, s. 1360-1369
-
Journal article (peer-reviewed)abstract
- Schizophrenia (SZ) is characterized by cognitive dysfunction and disorganized thought, in addition to hallucinations and delusions, and is regarded a disorder of brain connectivity. Recent efforts have been made to characterize the underlying brain network organization and interactions. However, to which degree connectivity alterations in SZ vary across different levels of cognitive effort is unknown. Utilizing independent component analysis (ICA) and methods for delineating functional connectivity measures from functional magnetic resonance imaging (fMRI) data, we investigated the effects of cognitive effort, SZ and their interactions on between-network functional connectivity during 2 levels of cognitive load in a large and well-characterized sample of SZ patients (n = 99) and healthy individuals (n = 143). Cognitive load influenced a majority of the functional connections, including but not limited to fronto-parietal and default-mode networks, reflecting both decreases and increases in between-network synchronization. Reduced connectivity in SZ was identified in 2 large-scale functional connections across load conditions, with a particular involvement of an insular network. The results document an important role of interactions between insular, default-mode, and visual networks in SZ pathophysiology. The interplay between brain networks was robustly modulated by cognitive effort, but the reduced functional connectivity in SZ, primarily related to an insular network, was independent of cognitive load, indicating a relatively general brain network-level dysfunction.
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| 4. |
- Carlsson, Göran, 1951, et al.
(author)
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Verbal and non-verbal function of children with right- versus left-hemiplegic cerebral palsy of pre- and perinatal origin.
- 1994
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In: Developmental medicine and child neurology. - 0012-1622. ; 36:6, s. 503-12
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Journal article (peer-reviewed)abstract
- Eighteen children with right- and 13 with left-sided congenital hemiplegia were compared with 19 normal age-matched controls for verbal and non-verbal function. CT scans were obtained from 27 of the 31 hemiplegic children. The two hemiplegic groups were impaired in non-verbal function compared with controls. The right-hemiplegic group was more impaired in verbal function than the left-hemiplegic group and controls; however, impairments were restricted to the girls in the right-hemiplegic group. The results are discussed in terms of cerebral plasticity and functional reorganisation of cognitive functions after an early unilateral injury. It is argued that girls with left-hemisphere lesions may be more limited in cerebral plasticity than boys.
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| 5. |
- Haugen, Olav H., et al.
(author)
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Cerebral Functional Magnetic Resonance Imaging and Multifocal Visual Evoked Potentials in a Patient with Unexplained Impairment of Visual Function : A Case Report
- 2018
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In: Case Reports in Ophthalmology. - : S. Karger AG. - 1663-2699. ; 9:2, s. 269-278
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Journal article (peer-reviewed)abstract
- We present a case of a young female with a slowly progressing visual impairment who was examined with multifocal visual evoked potentials and functional magnetic resonance imaging (fMRI) for underlying neuronal abnormality. The fMRI examination consisted of presenting black-and-white checkerboard stimuli, and her activation patterns were compared to the patterns from 4 normal-sighted subjects. The results showed clear differences in neuronal activation between the patient and the controls in the occipital and parietal lobes. Although we have shown neuronal correlates in a case of unexplained visual loss, it is still an open question as to whether this has an organic or functional cause, which should be the subject for future research.
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| 6. |
- Hugdahl, Kenneth
(author)
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Auditory Processing and Cognition
- 2014
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In: Understanding Developmental Disorders of Auditory Processing, Language And Literacy Across Languages. - CHARLOTTE : INFORMATION AGE PUBLISHING-IAP. - 9781623966645 - 9781623966652 ; , s. 41-65
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Conference paper (peer-reviewed)
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| 7. |
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| 8. |
- Kompus, Kristiina, et al.
(author)
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Deficits in inhibitory executive functions in Klinefelter (47, XXY) syndrome
- 2011
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In: Psychiatry Research. - : Elsevier BV. - 0165-1781 .- 1872-7123. ; 189:1, s. 135-140
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Journal article (peer-reviewed)abstract
- Klinefelter syndrome (47, XXY) is a sex chromosome aneuploidy associated with mild deficits in cognitive and language functions. Dysfunctions have also been reported in performance of tasks which examine executive functions. However, it is unclear whether the impaired performance is caused or accentuated by problems with semantic processing and information processing speed. In the present study we used an experimental task which is relatively insensitive to these confounding factors. We examined inhibitory executive functions in a group of XXY males compared with male (XY) and female (XX) controls, using a dichotic listening speech sound task with instructions to focus attention on either the right or the left ear stimulus. With this task, inhibitory executive functions can be assessed separately from language, processing speed, and attention orientation abilities. We found that XXY males showed a selective deficit in inhibitory executive functions compared to both control groups, whereas attentional orientation was not impaired. The present findings suggest that executive dysfunctions associated to Klinefelter syndrome can be selectively identified, and are particularly accentuated in the inhibitory sub-component. Such improved understanding of the nature of executive dysfunctions in XXY males may aid the development of specific neuropsychological rehabilitation strategies.
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| 9. |
- Kompus, Kristiina, 1983-, et al.
(author)
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Distinct control networks for cognition and emotion in the prefrontal cortex
- 2009
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In: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 467:2, s. 76-80
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Journal article (peer-reviewed)abstract
- The activation of dorsolateral prefrontal cortex (dlPFC) has been suggested to reflect the engagement of a control mechanism for top-down biasing of context processing in resource-demanding memory tasks. Here we tested the hypothesis that the dlPFC subserves a similar function also in attention and emotion tasks. 18 healthy young adults were tested in a functional magnetic resonance imaging (fMRI) study where the demands for context processing were manipulated in three different cognitive domains: auditory attention, episodic retrieval, and emotion regulation. We found that the right dlPFC was jointly sensitive to increased cognitive demands in the attention and memory tasks. By contrast, increased demands in the emotion task (reappraisal) were associated with increased activity in ventromedial PFC along with decreased amygdala activity. Our findings of divergent prefrontal control networks for cognitive and emotional control extend previous separations of cognition and emotion in the anterior cingulate cortex.
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| 10. |
- Kompus, Kristiina, 1983-, et al.
(author)
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Early analysis of retrieval cues guides selection of retrieval processing
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Other publication (other academic/artistic)abstract
- Human long-term memory holds semantic and episodic memories. Retrieval from these two memory systems occurs independently. As required information may be held in either of these systems, the question arises how and when is the choice of retrieval processing (episodic/semantic) determined. Here we report results from an ERP study on healthy young adults during a forced-choice associative recognition task, designed to test the hypothesis that early processing of retrieval cues influences subsequent retrieval processing. The test items had previously been encoded repeatedly (6x) or only once (1x) during pre-experimental training period, thereby influencing the reliance on semantic or episodic retrieval processes. Differences between the two conditions were observed for the familiarity-sensitive FN400 component as well as for a late (>1000 ms) component indexing post-retrieval processing. Most critically, we found that a difference between successfully retrieved 6x and 1x items emerged already during the 100-140 ms time window. These results indicate that choice of retrieval processes (episodic/semantic) depends on early matching between retrieval cues and memory traces.
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