| 1. |
- Elfgren, Christina, et al.
(författare)
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fMRI activity in the medial temporal lobe during famous face processing
- 2006
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Ingår i: NeuroImage. - : Elsevier BV. - 1095-9572 .- 1053-8119. ; 30:2, s. 609-616
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Tidskriftsartikel (refereegranskat)abstract
- The current event-related fMRI study examined the relative involvement of different parts of the medial temporal lobe (MTL), particularly the contribution of hippocampus and perirhinal cortex, in either intentional or incidental recognition of famous faces in contrast to unfamiliar faces. Our intention was to further explore the controversial contribution of MTL in the processing of semantic memory tasks. Subjects viewed a sequence of famous and unfamiliar faces. Two tasks were used encouraging attention to either fame or gender. In the fame task, the subjects were requested to identify the person when seeing his/her face and also to try to generate the name of this person. In the gender task, the subjects were asked to conduct a judgement of a person's gender when seeing his/her face. The visual processing was hence directed to gender and thereby expected to diminish attention to semantic information leading only to a “passive” registration of famous and non-familiar faces. Recognition of famous faces, in both contrasts, produced significant activations in the MTL. First, during the intentional recognition (the person identification task) increased activity was observed in the anterolateral part of left hippocampus, in proximity to amygdala. Second, during the incidental recognition of famous faces (the gender classification task), there was increased activity in the left posterior MTL with focus in the perirhinal cortex. Our results suggest that the hippocampus may be centrally involved in the intentional retrieval of semantic memories while the perirhinal cortex is associated with the incidental recognition of semantic information.
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| 2. |
- Mannfolk, Peter, et al.
(författare)
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Can resting-state functional MRI serve as a complement to task-based mapping of sensorimotor function? A test-retest reliability study in healthy volunteers.
- 2011
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 34, s. 511-517
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate if resting-state functional MRI (fMRI) reliably can serve as a complement to task-based fMRI for presurgical mapping of the sensorimotor cortex. MATERIALS AND METHODS: Functional data were obtained in 10 healthy volunteers using a 3 Tesla MRI system. Each subject performed five bilateral finger tapping experiments interleaved with five resting-state experiments. Following preprocessing, data from eight volunteers were further analyzed with the general linear model (finger tapping data) and independent component analysis (rest data). Test-retest reliability estimates (hit rate and false alarm rate) for resting-state fMRI activation of the sensorimotor network were compared with the reliability estimates for task-evoked activation of the sensorimotor cortex. The reliability estimates constituted a receiver operating characteristics curve from which the area under the curve (AUC) was calculated. Statistical testing was performed to compare the two groups with respect to reliability. RESULTS: The AUC was generally higher for the task experiments, although median AUC was not significantly different on a group level. Also, the two groups showed comparable levels of within-group variance. CONCLUSION: Test-retest reliability was comparable between resting-state measurements and task-based fMRI, suggesting that presurgical mapping of functional networks can be a supplement to task-based fMRI in cases where patient status excludes task-based fMRI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc.
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| 3. |
- Follin, Cecilia, et al.
(författare)
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Associations between Metabolic Risk Factors and the Hypothalamic Volume in Childhood Leukemia Survivors Treated with Cranial Radiotherapy.
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Metabolic complications are prevalent in individuals treated with cranial radiotherapy (CRT) for childhood acute lymphoblastic leukemia (ALL). The hypothalamus is a master regulator of endocrine and metabolic control. The aim of this study was to investigate whether the hypothalamic volume would be associated to metabolic parameters in ALL survivors. Thirty-eight (21 women) survivors participated in this study 34 years after diagnosis and with a median age of 38 (27-46) years. All were treated with a median CRT dose of 24 Gy and 11 years (3-13) of complete hormone supplementation. Comparisons were made to 31 matched controls. We performed analyses of fat mass, fat free mass, plasma (p)-glucose, p-insulin, Homa-Index (a measure of insulin resistance), serum (s)-leptin, s-ghrelin and of the hypothalamic volume in scans obtained by magnetic resonance imaging (MRI) at 3 Tesla. Serum leptin/kg fat mass (r = -0.4, P = 0.04) and fat mass (r = -0.4, P = 0.01) were negatively correlated with the HT volume among ALL survivors, but not among controls. We also detected significantly higher BMI, waist, fat mass, p-insulin, Homa-Index, leptin/kg fat mass and s-ghrelin and significantly lower fat free mass specifically among female ALL survivors (all P<0.01). Interestingly, s-ghrelin levels increased with time since diagnosis and with low age at diagnosis for childhood ALL. Our results showed that leptin/kg fat mass and fat mass were associated with a reduced HT volume 34 years after ALL diagnosis and that women treated with CRT after ALL are at high risk of metabolic abnormalities. Taken together our data suggest that the hypothalamus is involved in the metabolic consequences after CRT in ALL survivors.
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| 4. |
- Follin, Cecilia, et al.
(författare)
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Impaired brain metabolism and neurocognitive function in childhood leukemia survivors despite complete hormone supplementation in adulthood
- 2016
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Ingår i: Psychoneuroendocrinology. - : Elsevier BV. - 0306-4530 .- 1873-3360. ; 73, s. 157-165
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Tidskriftsartikel (refereegranskat)abstract
- Cranial radiotherapy is a known risk factor for neurocognitive impairment in survivors of childhood acute lymphoblastic leukemia (ALL). Understanding the nature of cognitive dysfunction during adulthood in ALL survivors is important as it has an impact on major life situations. Thirty-eight (21 women) ALL survivors were investigated 34 years after diagnosis. Median-age was 38 (27–46) years. All were treated with a CRT dose of 24 Gy and 11 years (3–13) of complete hormone supplementation. Comparisons were made to 29 matched controls. Assessments of magnetic resonance spectroscopy (white and grey matter metabolic alterations), brain volume and neuropsychological tests were performed. ALL survivors demonstrate a generally lower performance in neuropsychological tests. ALL survivors scored lower than controls in vocabulary (p < 0.001), memory (p < 0.001), learning capacity (p < 0.001), spatial ability (p < 0.001), executive functions and attention (p < 0.001) 34 years after ALL treatment. Compared to controls ALL survivors had reduced white matter (WM) (492 vs 536 cm3, p < 0.001) and grey matter (GM) volumes (525 vs 555 cm3, p = 0.001). ALL survivors had lower levels of WM N-acetyl aspartate/creatin (NAA/Cr) (1.48 vs 1.63, p = 0.004), WM NAA + NAAG (N-acetylaspartylglutamate)/Cr (1.61 vs 1.85, p < 0.001) and lower levels of GM NAA/Cr (1.18 vs 1.30, p = 0.001) and GM NAA + NAAG/Cr (1.28 vs 1.34, p = 0.01) compared to controls. ALL survivors had higher levels in WM MI (Myoinositol)/NAA (0.65 vs 0.56, p = 0.01) concentrations compared to controls. There was a significantly negative correlation of years since ALL diagnosis to WM NAA + NAAG/Cr (r = −0.4, p = 0.04) in ALL survivors. The present study shows impaired brain metabolism detected by MRS, reduced brain volumes and neurocognitive impairment in childhood ALL survivors treated with cranial radiotherapy and chemotherapy, despite complete hormone substitution. We also report an impairment of metabolites correlated to time since treatment and a progressive impairment in sustained attention, suggesting an accelerated aging in the irradiated brain. Following these survivors many decades, or throughout life, after treatment with cranial radiotherapy and chemotherapy is highly warranted for a broader understanding of long-term outcome in this patient group.
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| 5. |
- Mannfolk, Peter, et al.
(författare)
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Assessment of spatial BOLD sensitivity variations in fMRI using gradient-echo field maps.
- 2010
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 28:7, s. 947-956
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Tidskriftsartikel (refereegranskat)abstract
- Clinical blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is becoming increasingly valuable in, e.g., presurgical planning, but the commonly used gradient-echo echo-planar imaging (GE-EPI) technique is sometimes hampered by macroscopic field inhomogeneities. This can affect the degree of signal change that will occur in the GE-EPI images as a response to neural activation and the subsequent blood oxygenation changes, i.e., the BOLD sensitivity (BS). In this study, quantitative BS maps were calculated directly from gradient-echo field maps obtainable on most clinical scanners. In order to validate the accuracy of the calculated BS-maps, known shim gradients were applied and field maps and GE-EPI images of a phantom were acquired. Measured GE-EPI image intensity was then compared with the calculated (predicted) image intensity (pII) which was obtained from the field maps using theoretical expressions for image-intensity loss. The validated expressions for pII were used to calculate the corresponding predicted BOLD sensitivity (pBS) maps in healthy volunteers. Since the field map is assumed to be valid throughout an entire fMRI experiment, the influence of subject motion on the pBS maps was also assessed. To demonstrate the usefulness of such maps, pBS was investigated for clinically important functional areas including hippocampus, Broca's area and primary motor cortex. A systematic left/right pBS difference was observed in Broca's area and in the hippocampus, most likely due to magnetic field inhomogeneity of the particular MRI-system used in this study. For all subjects, the hippocampus showed pBS values above unity with a clear anterior-posterior gradient and with an abrupt drop to zero pBS in the anterior parts of hippocampus. It is concluded that GE field maps can be used to accurately predict BOLD sensitivity and that this parameter is useful to assess spatial variations which will influence fMRI experiments.
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| 6. |
- Mannfolk, Peter, et al.
(författare)
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Dimensionality reduction of fMRI time series data using locally linear embedding.
- 2010
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Ingår i: Magma. - : Springer Science and Business Media LLC. - 1352-8661. ; 23:5-6, s. 327-338
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Data-driven methods for fMRI analysis are useful, for example, when an a priori model of signal variations is unavailable. However, activation sources are typically assumed to be linearly mixed, although non-linear properties of fMRI data, including resting-state data, have been observed. In this work, the non-linear locally linear embedding (LLE) algorithm is introduced for dimensionality reduction of fMRI time series data. MATERIALS AND METHODS: LLE performance was optimised and tested using simulated and volunteer data for task-evoked responses. LLE was compared with principal component analysis (PCA) as a preprocessing step to independent component analysis (ICA). Using an example data set with known non-linear properties, LLE-ICA was compared with PCA-ICA and non-linear PCA-ICA. A resting-state data set was analysed to compare LLE-ICA and PCA-ICA with respect to identifying resting-state networks. RESULTS: LLE consistently found task-related components as well as known resting-state networks, and the algorithm compared well to PCA. The non-linear example data set demonstrated that LLE, unlike PCA, can separate non-linearly modulated sources in a low-dimensional subspace. Given the same target dimensionality, LLE also performed better than non-linear PCA. CONCLUSION: LLE is promising for fMRI data analysis and has potential advantages compared with PCA in terms of its ability to find non-linear relationships.
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| 7. |
- Mannfolk, Peter
(författare)
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Methodological Aspects of Clinical fMRI - Reliability Assessment and Development of Data Analysis Strategies
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Functional magnetic resonance imaging (fMRI) is a non-invasive technique used for the investigation of brain function, which has found numerous applications within basic neuroscience. The introduction of fMRI as a clinical tool for presurgical mapping of pertinent cortical regions in patients with tumour or epilepsy has facilitated neurosurgical planning, and most likely reduced the risk of severe postoperative deficits. However, there is a fundamental difference between the application of fMRI in experimental research and in the clinical setting. While inference is often drawn from data on group level in neuroscientific applications of fMRI, the clinical use of the method demands that reliable results be obtained in individual patients. The aims of the methodological studies presented in this thesis were to increase the reliability and extend the usefulness of clinical fMRI. In one study, gradient-echo field maps were utilized to assess the sensitivity of echo-planar imaging to the blood oxygenation level dependent (BOLD) contrast. Theoretical expressions for the calculation of the BOLD sensitivity were verified and improved. The BOLD sensitivity was investigated in a group of healthy volunteers using a clinical magnetic resonance imaging (MRI) system, and it was concluded that the field map method accurately predicts BOLD sensitivity. In another study, a flexible model was introduced in order to increase the confidence of clinical fMRI examinations of patients unable to fully comply with a typical clinical fMRI experiment. The method was applied to experimental and simulated data, and then used to retrospectively analyse patient data. The conclusion drawn from this study was that the proposed flexible model improves the detection of activation in partially non-compliant subjects. In the third study included in this thesis, the model-free algorithm locally linear embedding was applied to fMRI data analysis. The proposed data-driven algorithm was optimized and investigated with respect to reliability and possible benefits in a clinical setting. The algorithm was found to compare well to the traditionally used method of principal component analysis, and showed benefits when applied to simulated fMRI data exhibiting non-linear characteristics. Finally, the test-retest reliability of resting-state fMRI was compared with the reliability of traditional task-based fMRI. Resting-state fMRI compared well with task-based fMRI experiments, thus possibly extending the use of fMRI to patient groups that have hitherto not been able to benefit from fMRI examinations.
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| 8. |
- Maripuu, Amanda, et al.
(författare)
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Reconstruction of sciatic nerve after traumatic injury in humans - factors influencing outcome as related to neurobiological knowledge from animal research
- 2012
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Ingår i: Journal of Brachial Plexus and Peripheral Nerve Injury. - : Georg Thieme Verlag KG. - 1749-7221. ; 7:1, s. 40-52
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Forskningsöversikt (refereegranskat)abstract
- Background: The aim was to evaluate what can be learned from rat models when treating patients suffering from a sciatic nerve injury.Methods: Two patients with traumatic sciatic nerve injury are presented with examination of motor and sensory function with a five-year follow-up. Reconstruction of the nerve injury was performed on the second and third day, respectively, after injury using sural nerve grafts taken from the injured leg. The patients were examined during follow-up by electromyography (EMG), MRI and functionalMRI (fMRI) to evaluate nerve reinnervation, cell death in dorsal root ganglia (DRG) and cortical activation; factors that were related to clinical history in the patients.Results: One patient regained good motor function of the lower leg and foot, confirmed by EMG showing good activation in the leg muscles and some reinnervation in the foot muscles, as well as some sensory function of the sole of the foot. The other patient regained no motor (confirmed by EMG) or sensory function in the leg or foot. Factors most influential on outcome in two cases were type of injury, nerve gap length and particularly type of reconstruction. A difference in follow-up and rehabilitation likely also influence outcome. MRI did not show any differences in DRG size of injured side compared to the uninjured side. fMRI showed normal activation in the primary somatosensory cortex as a response to cutaneous stimulation of the normal foot. However, none of the two patients showed any activation in the primary somatosensory cortex following cutaneous stimulation of the injured foot.Conclusions: In decision making of nerve repair and reconstruction data from animal experiments can be translated to clinical practice and to predict outcome in patients, although such data should be interpreted with caution and linked to clinical experience. Rat models may be useful to identify and study factors that influence outcome after peripheral nerve repair and reconstruction; procedures that should be done correctly and with a competent team. However, some factors, such as cognitive capacity and coping, known to influence outcome following nerve repair, are difficult to study in animal models. Future research has to find and develop new paths and techniques to study changes in the central nervous system after nerve injury and develop strategies to utilize brain plasticity during the rehabilitation.
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| 9. |
- Nystedt, Jessika, et al.
(författare)
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Altered white matter microstructure in lupus patients : A diffusion tensor imaging study
- 2018
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Ingår i: Arthritis Research and Therapy. - : Springer Science and Business Media LLC. - 1478-6354 .- 1478-6362. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The purpose of this study was to investigate whether white matter microstructure is altered in patients suffering from systemic lupus erythematosus (SLE), and if so, whether such alterations differed between patients with and without neuropsychiatric symptoms. Methods: Structural MRI and diffusion tensor imaging (DTI) were performed in 64 female SLE patients (mean age 36.9 years, range 18.2-52.2 years) and 21 healthy controls (mean age 36.7 years, range 23.3-51.2 years) in conjunction with clinical examination, laboratory tests, cognitive evaluation, and self-assessment questionnaires. The patients were subgrouped according to the American College of Rheumatology Neuropsychiatric Systemic Lupus Erythematosus case definitions into non-neuropsychiatric SLE (nonNPSLE) and neuropsychiatric SLE (NPSLE). Results: Comparisons between the SLE group and healthy controls showed that the mean fractional anisotropy (FA) was significantly reduced in the right rostral cingulum (p=0.038), the mid-sagittal corpus callosum (CC) (p=0.050), and the forceps minor of the CC (p=0.015). The mean diffusivity (MD) was significantly increased in the left hippocampal cingulum (p=0.017). No significant differences in MD or FA values were identified between NPSLE and nonNPSLE patients. Disease duration among all SLE patients correlated significantly with reduced FA in the CC (p<0.05). No correlations were found between DTI parameters and white matter hyperintensities, SLE Disease Activity Index-2000, Systemic Lupus International Collaborating Clinical/ACR Organ Damage Index, or Montgomery Asberg Depression Rate Score Self-report. Conclusions: We found alterations of white matter microstructure in SLE patients that were related to disease duration and fatigue. Our results indicate that cerebral involvement in SLE is not isolated to the NPSLE subgroup.
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| 10. |
- Nystedt, Jessika, et al.
(författare)
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Functional connectivity changes in core resting state networks are associated with cognitive performance in systemic lupus erythematosus
- 2019
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Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 527:11, s. 1837-1856
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Tidskriftsartikel (refereegranskat)abstract
- To investigate core resting state networks in SLE patients with and without neuropsychiatric symptoms by examining functional connectivity changes correlating with results of cognitive testing. Structural MRI and resting state-fMRI (rs-fMRI) were performed in 61 female SLE patients (mean age: 36.8 years, range 18.2–52.0 years) and 20 healthy controls (HC) (mean age 36.2 years, range 23.3–52.2 years) in conjunction with clinical examination and cognitive testing. Alterations in core resting state networks, not found in our healthy controls sample, correlated with cognitive performance gauged by neuropsychological tests in non-neuropsychiatric SLE (nNP) as well as in neuropsychiatric SLE patients (NP). The observed pattern of increased functional connectivity in core resting state networks correlated with reduced cognitive performance on all cognitive domains tested and with a heavy focus on DM, CE, and DM–CE in the NP subgroup. Furthermore, we found that the observed alterations in memory and psychomotor speed correlated with disease duration. In SLE patients both with and without clinically overt neuropsychiatric manifestations, we found changes in the functional connectivity of core resting state networks essential to cognitive functions. These findings may represent a rewiring of functional architecture in response to neuronal damage and could indicate suboptimal compensatory mechanisms at play.
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| 11. |
- Nystedt, Jessika, et al.
(författare)
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Functional Connectivity Changes in Systemic Lupus Erythematosus : A Resting-State Study
- 2018
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Ingår i: Brain Connectivity. - : Mary Ann Liebert Inc. - 2158-0014 .- 2158-0022. ; 8:4, s. 220-234
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Tidskriftsartikel (refereegranskat)abstract
- To investigate resting-state functional connectivity of lupus patients and associated subgroups according to the ACR NPSLE case definitions (ACR ad hoc). In addition, we investigated whether or not the observed alterations correlated with disease duration, the systemic lupus erythematosus (SLE)-Disease Activity Index-2000 (SLEDAI-2k), and Systemic Lupus International Collaborating Clinical/ACR organ damage index (SDI)-scores. Anatomical 3T magnetic resonance imaging (MRI) and resting-state functional MRI were performed in 61 female lupus patients (mean age = 37.0 years, range = 18.2-52.0 years) and 20 gender- and age-matched controls (mean age = 36.2 years, range = 23.3-52.2 years) in conjunction with clinical examination and laboratory testing. Whole-brain voxelwise functional connectivity analysis with permutation testing was performed to extract network components that differed in lupus patients relative to healthy controls (HCs). Lupus patients exhibited both inter- and intranetwork hypo- and hyperconnectivity involving several crucial networks. We found reduced connectivity within the default mode network (DMN), the central executive network (CEN), and in-between the DMN and CEN in lupus patients. Increased connectivity was primarily observed within and between the sensory motor network in lupus patients when compared to HCs. Comparing lupus patients with and without neuropsychiatric symptoms, hypoconnectivity was more pronounced in the group with neuropsychiatric complaints. The functional connectivity of SLE patients was both positively and negatively correlated to duration of disease. We conclude that SLE patients in general and neuropsychiatric SLE patients in particular experience altered brain connectivity. These patterns may be due both to direct neuronal damage and compensatory mechanisms through neuronal rewiring and recruitment and may partly explain neuropsychiatric symptoms in SLE patients.
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| 12. |
- Olsrud, Johan, et al.
(författare)
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A two-compartment gel phantom for optimization and quality assurance in clinical BOLD fMRI
- 2008
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 26:2, s. 279-286
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Tidskriftsartikel (refereegranskat)abstract
- Clinical applications of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) depend heavily on robust paradigms, imaging methods and analysis procedures. In this work, as a means to optimize and perform quality assurance of the entire imaging and analysis chain, a phantom that provides a well known and reproducible signal change similar to a block type fMRI experiment is presented. It consists of two gel compartments with slightly different T(2) that dynamically enter and leave the imaged volume. The homogeneous gel in combination with a cylindrical geometry results in a well-defined T(2) difference causing a signal difference between the two compartments in T(2)-weighted MR images. From time series data obtained with the phantom, maps of percent signal change (PSC) and t-values are calculated. As an example of image parameter optimisation, the phantom is demonstrated to be useful for accurate determination of the influence of echo time (TE) on BOLD fMRI results, taking the t-value as a measure of sensitivity. In addition, the phantom is proposed as a tool for quality assurance (QA) since reproducible time series and t-maps are obtained in a series of independent repeat experiments. The phantom is relatively simple to build and can therefore be used by any clinical fMRI center.
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| 13. |
- Roll, Mikael, et al.
(författare)
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Forehearing words : Pre-activation of word endings at word onset
- 2017
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940. ; 658, s. 57-61
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Tidskriftsartikel (refereegranskat)abstract
- Occurring at rates up to 6-7 syllables per second, speech perception and understanding involves rapid identification of speech sounds and pre-activation of morphemes and words. Using event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), we investigated the time-course and neural sources of pre-activation of word endings as participants heard the beginning of unfolding words. ERPs showed a pre-activation negativity (PrAN) for word beginnings (first two segmental phonemes) with few possible completions. PrAN increased gradually as the number of possible completions of word onsets decreased and the lexical frequency of the completions increased. The early brain potential effect for few possible word completions was associated with a blood-oxygen-level-dependent (BOLD) contrast increase in Broca’s area (pars opercularis of the left inferior frontal gyrus) and angular gyrus of the left parietal lobe. We suggest early involvement of the left prefrontal cortex in inhibiting irrelevant left parietal activation during lexical selection. The results further our understanding of the importance of Broca’s area in rapid online pre-activation of words.
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| 14. |
- Roll, Mikael, et al.
(författare)
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Word tones cueing morphosyntactic structure: Neuroanatomical substrates and activation time-course assessed by EEG and fMRI.
- 2015
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Ingår i: Brain and Language. - : Elsevier BV. - 1090-2155 .- 0093-934X. ; 150, s. 14-21
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies distinguish between right hemisphere-dominant processing of prosodic/tonal information and left-hemispheric modulation of grammatical information as well as lexical tones. Swedish word accents offer a prime testing ground to better understand this division. Although similar to lexical tones, word accents are determined by words' morphosyntactic structure, which enables listeners to use the tone at the beginning of a word to predict its grammatical ending. We recorded electrophysiological and hemodynamic brain responses to words where stem tones matched or mismatched inflectional suffixes. Tones produced brain potential effects after 136ms, correlating with subject variability in average BOLD in left primary auditory cortex, superior temporal gyrus, and inferior frontal gyrus. Invalidly cued suffixes activated the left inferior parietal lobe, arguably reflecting increased processing cost of their meaning. Thus, interaction of word accent tones with grammatical morphology yielded a rapid neural response correlating in subject variability with activations in predominantly left-hemispheric brain areas.
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| 15. |
- Rumetshofer, Theodor, et al.
(författare)
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Tract-based white matter hyperintensity patterns in patients with systemic lupus erythematosus using an unsupervised machine learning approach
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Currently, little is known about the spatial distribution of white matter hyperintensities (WMH) in the brain of patients with Systemic Lupus erythematosus (SLE). Previous lesion markers, such as number and volume, ignore the strategic location of WMH. The goal of this work was to develop a fully-automated method to identify predominant patterns of WMH across WM tracts based on cluster analysis. A total of 221 SLE patients with and without neuropsychiatric symptoms from two different sites were included in this study. WMH segmentations and lesion locations were acquired automatically. Cluster analysis was performed on the WMH distribution in 20 WM tracts. Our pipeline identified five distinct clusters with predominant involvement of the forceps major, forceps minor, as well as right and left anterior thalamic radiations and the right inferior fronto-occipital fasciculus. The patterns of the affected WM tracts were consistent over the SLE subtypes and sites. Our approach revealed distinct and robust tract-based WMH patterns within SLE patients. This method could provide a basis, to link the location of WMH with clinical symptoms. Furthermore, it could be used for other diseases characterized by presence of WMH to investigate both the clinical relevance of WMH and underlying pathomechanism in the brain.
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| 16. |
- Strandberg, Maria, et al.
(författare)
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A Functional MRI-Based Model for Individual Memory Assessment in Patients Eligible for Anterior Temporal Lobe Resection.
- 2017
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Ingår i: The open neuroimaging journal. - : Bentham Science Publishers Ltd.. - 1874-4400. ; 11, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- TITLE: A functional (f) MRI-based model for individual memory assessment in patients eligible for temporal lobe resection.AIM: To investigate if pre-operative fMRI memory paradigms, add predictive information with regard to post-surgical memory deficits.METHODS: Fourteen pharmacoresistant Temporal Lobe Epilepsy (TLE) patients accepted for Anterior Temporal Lobe Resection (ATLR) were included. A clinical risk assessment score (RAS 0-3) was constructed from structural MRI, neuropsychological testing and hemisphere dominance. fMRI lateralization indices (LIs) over frontal language and medial temporal regions were calculated. Predictive value from clinical risk scoring and added value from fMRI LIs were correlated to post-surgical memory change scores (significant decline -1 SD). Verbal memory outcome was classified either as expected (RAS 2-3 and post-operative decline; RAS 0-1 and intact post-operative verbal memory) or as unexpected (RAS 2-3 and intact post-operative verbal memory post-surgery; RAS 0-1 and post-operative decline).RESULTS: RAS for verbal memory decline exhibited a specificity of 67% and a sensitivity of 75%. Significant correlations were found between frontal language LIs and post-operative verbal memory (r = -0.802; p = 0.017) for left (L) TLE and between medial temporal lobe LIs and visuospatial memory (r = 0.829; p = 0.021), as well as verbal memory (r = 0.714; p = 0.055) for right (R) TLE. Ten patients had expected outcome and four patients had an unexpected outcome. In two MRI-negative RTLE patients that suffered significant verbal memory decline post-operatively, fMRI identified bilateral language and right lateralized medial temporal verbal encoding. In two LTLE patients with MRI pathology and verbal memory dysfunction, neither RAS nor fMRI identified the risk for aggravated verbal memory decline following ATLR.CONCLUSION: fMRI visualization of temporal-frontal network activation may add value to the pre-surgical work-up in epilepsy patients eligible for ATLR. Frontal language patterns are important for prediction in both L and RTLE. Strong left lateralized language in LTLE, as well as bilateral language combined with right lateralized encoding in RTLE, seems to indicate an increased risk for post-operative verbal memory decline.
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| 17. |
- Strandberg, Maria, et al.
(författare)
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fMRI memory assessment in healthy subjects : a new approach to view lateralization data at an individual level
- 2011
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Ingår i: Brain Imaging and Behavior. - : Springer Science and Business Media LLC. - 1931-7557 .- 1931-7565. ; 5:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- We present a comprehensive and clinically applicable fMRI test-including both a verbal and a visuospatial task-for assessment of hemispheric specific memory in the medial temporal lobe (MTL). fMRI data was collected from 15 healthy right-handed volunteers. Whole-brain activation was analyzed as well as activation in two regions of interest: the MTL and the anterior speech area. Laterality indices (LI) and LI-curves were calculated using the LI toolbox of Wilke and Lidzba, 2007. The fMRI paradigms successfully visualized memory-related activity in the MTL, the verbal memory measure also provided information of language lateralization. Eleven subjects showed left lateralized verbal encoding in the MTL, visuospatial memory activation was divided equally between left and right, and 14/15 subjects had left lateralized language. Lateralization data at the group level were consistent with previous studies, but a variety of activation effects were found at the individual level indicating differences in strategy during verbal and visuospatial processing. Further studies using the presented method are needed to determine its clinical usefulness.
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| 18. |
- Strandberg, Maria, et al.
(författare)
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Verbal encoding fMRI paradigm adds complementary information to cerebral language lateralization
- 2015
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Ingår i: Annals of neuroscience and psychology. - 2058-7805.
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Tidskriftsartikel (refereegranskat)abstract
- Title: Verbal encoding fMRI paradigm adds complementary information to cerebrallanguage lateralization.Purpose: To explore two conceptually different fMRI paradigms’ ability to lateralizelanguage.Methods: A verbal encoding paradigm and a word generation task were performed bysix patients (four right-handed) with therapy-resistant temporal lobe epilepsy (TLE),and by ten healthy individuals (five right-handed). FMRI laterality indices (LI) andlaterality curves for the anterior cerebral language regions were calculated. Typicallateralization was defined as left-hemisphere dominance, and a typical as bilateral orright-hemisphere dominance.Results: Both paradigms showed predominantly left-sided activation in the anteriorlanguage regions, with typical contralateral cerebellar activity. Thirteen out of sixteensubjects showed concordant language lateralization results for both paradigms.Two subjects, both left-handed, showed discordant language lateralization results.Laterality curves added information for individual subjects with uncharacteristicresults. The verbal encoding task showed overall more widespread activationcompared to the word generation task.Conclusion: Our results indicate valid language lateralization obtained by the fMRIverbal encoding paradigm for right-handed subjects. This offers the opportunity tosimultaneously study two cognitive functions, language and verbal encoding, usingone task. TLE is a network disease which predisposes afflicted patients to cortical reorganizationand inserting uncertainties regarding hemisphere dominance. Atypicallanguage representation in connection with left-handedness should be interpretedwith caution irrespective of which paradigm is chosen.Keywords: TLE, fMRI, handedness, lateralization index, language lateralization
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| 20. |
- Svärd, Daniel, et al.
(författare)
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Cognitive interference processing in adult survivors of childhood acute lymphoblastic leukemia using functional magnetic resonance imaging
- 2022
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Ingår i: Acta Oncologica. - 1651-226X. ; 61:3, s. 333-340
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Tidskriftsartikel (refereegranskat)abstract
- Background: Childhood acute lymphoblastic leukemia (ALL) is associated with cognitive impairment in adulthood. Cognitive interference processing and its correlated functional magnetic resonance imaging (fMRI) activity in the brain have not yet been studied in this patient group.Material: Twenty-six adult childhood ALL survivors (median [interquartile range {IQR}] age, 40.0 [37.0-42.3] years) were investigated at median age (IQR), 35.0 (32.0-37.0) years after treatment with intrathecal and intravenous chemotherapy as well as cranial radiotherapy (24 Gy) and compared with 26 matched controls (median [IQR] age, 37.5 [33.0-41.5] years).Methods: Cognitive interference processing was investigated in terms of behavioral performance (response times [ms] and accuracy performance [%]) and fMRI activity in the cingulo-fronto-parietal (CFP) attention network as well as other parts of the brain using the multisource interference task (MSIT).Results: ALL survivors had longer response times and reduced accuracy performance during cognitive interference processing (median [IQR] interference effect, 371.9 [314.7-453.3] ms and 6.7 [4.2-14.7]%, respectively) comparedwith controls (303.7 [275.0-376.7] ms and 2.3 [1.6-4.3]%, respectively), but did not exhibit altered fMRI activity in the CFP attention network or elsewhere in the brain.Conclusion: Adult childhood ALL survivors demonstrated impaired behavioral performance but no altered fMRI activity when performing cognitive interference processing when compared with controls. The results can be used to better characterize this patient group and to optimize follow-up care and support for these individuals.
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| 21. |
- Svärd, Daniel, et al.
(författare)
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Cognitive interference processing in adults with childhood craniopharyngioma using functional magnetic resonance imaging
- 2021
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Ingår i: Endocrine. - : Springer Science and Business Media LLC. - 1355-008X .- 1559-0100. ; 74:3, s. 714-722
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To assess cognitive interference processing in adults with childhood craniopharyngioma (CP), with and without hypothalamic injury, respectively, in terms of behavioral performance and functional magnetic resonance imaging (fMRI) activity, using the multi-source interference task (MSIT).METHODS: Twenty-eight CP patients (median age 34.5 [29.0-39.5] years) were investigated at median 20.5 (16.3-28.8) years after treatment with surgical resection and in some cases additional radiotherapy (n = 10) and compared to 29 matched controls (median age 37.0 [32.5-42.0] years). The subjects performed the MSIT during fMRI acquisition and behavioral performance in terms of response times (ms) and accuracy performance (%) were recorded.RESULTS: The MSIT activated the cingulo-fronto-parietal (CFP) attention network in both CP patients and controls. No differences were found in behavioral performance nor fMRI activity between CP patients (interference effect 333.9 [287.3-367.1] ms and 3.1 [1.6-5.6]%, respectively) and controls (309.1 [276.4-361.0] ms and 2.6 [1.6-4.9]%). No differences were found in behavioral performance nor fMRI activity between the two subgroups with (332.0 [283.6-353.4] ms and 4.2 [2.3-5.7]%, respectively) and without hypothalamic injury (355.7 [293.7-388.7] ms and 2.1 [1.0-5.2]%, respectively), respectively, and controls.CONCLUSION: Adults with childhood CP performed cognitive interference processing equally well as controls and demonstrated no compensatory fMRI activity in the CFP attention network compared to controls. This was also true for the two subgroups with and without hypothalamic injury. The results can be useful to better characterize this condition, and to optimize treatment and support for these individuals.
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| 23. |
- Söderström, Pelle, et al.
(författare)
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Anticipating morphological and syntactic structures : investigating the pre-activation negativity
- 2017
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Konferensbidrag (refereegranskat)abstract
- It is known that listeners can predict upcoming words based on constraining contexts (e.g. DeLong et al., 2005). In a recent study, we proposed a left frontal brain potential, the pre-activation negativity, PrAN (Söderström et al., 2016), thought to reflect pre-activation of expected word continuations. Time-locked to word-initial fragments, PrAN’s amplitude was found to increase in a 136-280 ms time window as the number of possible continuations decreased, suggesting that PrAN increased with increased predictive certainty about a word’s ending. In the present study, we tested whether a similar effect could be found for pre-activation of expected syntactic structures. In Swedish, intonation is used to signal whether an unfolding embedded clause is a main or subordinate clause. Specifically, a clause-initial word with a low boundary tone cues only subordinate clause structure. Conversely, a corresponding high tone signals that any kind of embedded main clause structure may follow, i.e. it cues a more open set of structures. Test participants listened to complex sentences and judged the word order of the verb (V) and negation (NEG) after the boundary tone as quickly as possible (NEG–V word order occurs in subordinate clauses and V–NEG in main clauses). ERPs were time-locked to the tone-bearing syllable. A repeated-measures ANOVA showed a negativity in left anterior electrodes at 136-280 ms for low initial boundary tones, which cue only subordinate clauses. We propose that this effect is a PrAN, but that it here reflects pre-activation of syntactic structures rather than possible word endings.
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| 24. |
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| 25. |
- Söderström, Pelle, et al.
(författare)
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Rapid syntactic pre-activation in Broca’s area : Concurrent electrophysiological and haemodynamic recordings
- 2018
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 1697, s. 76-82
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Tidskriftsartikel (refereegranskat)abstract
- Listeners are constantly trying to predict what the speaker will say next. We concurrently measured the electrophysiological and haemodynamic correlates of syntactic pre-activation, investigating when and where the brain processes speech melody cues to upcoming word order structure. Pre-activation of syntactic structure was reflected in a left-lateralised pre-activation negativity (PrAN), which was subserved by Broca’s area in the left inferior frontal gyrus, as well as the contiguous left anterior insula.
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| 28. |
- Vult von Steyern, Fredrik, et al.
(författare)
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Giant-cell tumour of the knee - The condition of the cartilage after treatment by curettage and cementing
- 2007
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 2044-5377. ; 89B:3, s. 361-365
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Tidskriftsartikel (refereegranskat)abstract
- We reviewed nine patients at a mean period of 11 years ( 6 to 16) after curettage and cementing of a giant-cell tumour around the knee to determine if there were any long-term adverse effects on the cartilage. Plain radiography, MRI, delayed gadolinium-enhanced MRI of the cartilage and measurement of the serum level of cartilage oligomeric matrix protein were carried out. The functional outcome was evaluated using the Lysholm knee score. Each patient was physically active and had returned to their previous occupation. Most participated in recreational sports or exercise. The mean Lysholm knee score was 92 ( 83 to 100). Only one patient was found to have cartilage damage adjacent to the cement. This patient had a history of intra-articular fracture and local recurrence, leading to degenerative changes. Interpretation of the data obtained from delayed gadolinium-enhanced MRI of the cartilage was difficult, with variation in the T1 values which did not correlate with the clinical or radiological findings. We did not find it helpful in the early diagnosis of degeneration of cartilage. We also found no obvious correlation between the serum cartilage oligomeric matrix protein level and the radiological and MR findings, function, time after surgery and the age of the patient. In summary, we found no evidence that the long-term presence of cement close to the knee joint was associated with the development of degenerative osteoarthritis.
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| 29. |
- Waites, Anthony B, et al.
(författare)
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Flexible statistical modelling detects clinical functional magnetic resonance imaging activation in partially compliant subjects.
- 2007
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 25:2, s. 188-196
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Tidskriftsartikel (refereegranskat)abstract
- Clinical functional magnetic resonance imaging (MRI) occasionally fails to detect significant activation, often due to variability in task performance. The present study seeks to test whether a more flexible statistical analysis can better detect activation, by accounting for variance associated with variable compliance to the task over time. Experimental results and simulated data both confirm that even at 80% compliance to the task, such a flexible model outperforms standard statistical analysis when assessed using the extent of activation (experimental data), goodness of fit (experimental data), and area under the operator characteristic curve (simulated data). Furthermore, retrospective examination of 14 clinical fMRI examinations reveals that in patients where the standard statistical approach yields activation, there is a measurable gain in model performance in adopting the flexible statistical model, with little or no penalty in lost sensitivity. This indicates that a flexible model should be considered, particularly for clinical patients who may have difficulty complying fully with the study task. (c) 2007 Elsevier Inc. All rights reserved.
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