SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "L773:1053 8119 OR L773:1095 9572 "

Sökning: L773:1053 8119 OR L773:1095 9572

  • Resultat 1-10 av 477
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Petersson, KM, et al. (författare)
  • Instruction-specific brain activations during episodic encoding: a generalized level of processing effect
  • 2003
  • Ingår i: NeuroImage. - 1095-9572 .- 1053-8119. ; 20:3, s. 1795-1810
  • Tidskriftsartikel (refereegranskat)abstract
    • In a within-subject design we investigated the levels-of-processing (LOP) effect using visual material in a behavioral and a corresponding PET study. In the behavioral study we characterize a generalized LOP effect, using pleasantness and graphical quality judgments in the encoding situation, with two types of visual material, figurative and nonfigurative line drawings. In the PET study we investigate the related pattern of brain activations along these two dimensions. The behavioral results indicate that instruction and material contribute independently to the level of recognition performance. Therefore the LOP effect appears to stem both from the relative relevance of the stimuli (encoding opportunity) and an altered processing of stimuli brought about by the explicit instruction (encoding mode). In the PET study, encoding of visual material under the pleasantness (deep) instruction yielded left lateralized frontoparietal and anterior temporal activations while surface-based perceptually oriented processing (shallow instruction) yielded right lateralized frontoparietal, posterior temporal, and occipitotemporal activations. The result that deep encoding was related to the left prefrontal cortex while shallow encoding was related to the right prefrontal cortex, holding the material constant, is not consistent with the HERA model. In addition, we suggest that the anterior medial superior frontal region is related to aspects of self-referential semantic processing and that the inferior parts of the anterior cingulate as well as the medial orbitofrontal cortex is related to affective processing, in this case pleasantness evaluation of the stimuli regardless of explicit semantic content. Finally, the left medial temporal lobe appears more actively engaged by elaborate meaning-based processing and the complex response pattern observed in different subregions of the MTL lends support to the suggestion that this region is functionally segregated.
  •  
2.
  • Friman, Ola, et al. (författare)
  • Adaptive analysis of fMRI data
  • 2003
  • Ingår i: NeuroImage. - 1053-8119 .- 1095-9572. ; 19:3, s. 837-845
  • Tidskriftsartikel (refereegranskat)abstract
    • This article introduces novel and fundamental improvements of fMRI data analysis. Central is a technique termed constrained canonical correlation analysis, which can be viewed as a natural extension and generalization of the popular general linear model method. The concept of spatial basis filters is presented and shown to be a very successful way of adaptively filtering the fMRI data. A general method for designing suitable hemodynamic response models is also proposed and incorporated into the constrained canonical correlation approach. Results that demonstrate how each of these parts significantly improves the detection of brain activity, with a computation time well within limits for practical use, are provided.
  •  
3.
  •  
4.
  •  
5.
  • Abramian, David, 1992-, et al. (författare)
  • Diffusion-Informed Spatial Smoothing of fMRI Data in White Matter Using Spectral Graph Filters
  • 2021
  • Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 237
  • Tidskriftsartikel (refereegranskat)abstract
    • Brain activation mapping using functional magnetic resonance imaging (fMRI) has been extensively studied in brain gray matter (GM), whereas in large disregarded for probing white matter (WM). This unbalanced treatment has been in part due to controversies in relation to the nature of the blood oxygenation level-dependent (BOLD) contrast in WM and its detachability. However, an accumulating body of studies has provided solid evidence of the functional significance of the BOLD signal in WM and has revealed that it exhibits anisotropic spatio-temporal correlations and structure-specific fluctuations concomitant with those of the cortical BOLD signal. In this work, we present an anisotropic spatial filtering scheme for smoothing fMRI data in WM that accounts for known spatial constraints on the BOLD signal in WM. In particular, the spatial correlation structure of the BOLD signal in WM is highly anisotropic and closely linked to local axonal structure in terms of shape and orientation, suggesting that isotropic Gaussian filters conventionally used for smoothing fMRI data are inadequate for denoising the BOLD signal in WM. The fundamental element in the proposed method is a graph-based description of WM that encodes the underlying anisotropy observed across WM, derived from diffusion-weighted MRI data. Based on this representation, and leveraging graph signal processing principles, we design subject-specific spatial filters that adapt to a subject’s unique WM structure at each position in the WM that they are applied at. We use the proposed filters to spatially smooth fMRI data in WM, as an alternative to the conventional practice of using isotropic Gaussian filters. We test the proposed filtering approach on two sets of simulated phantoms, showcasing its greater sensitivity and specificity for the detection of slender anisotropic activations, compared to that achieved with isotropic Gaussian filters. We also present WM activation mapping results on the Human Connectome Project’s 100-unrelated subject dataset, across seven functional tasks, showing that the proposed method enables the detection of streamline-like activations within axonal bundles.
  •  
6.
  • Ahs, Fredrik, et al. (författare)
  • High-frequency heart rate variability and cortico-striatal activity in men and women with social phobia
  • 2009
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 47:3, s. 815-820
  • Tidskriftsartikel (refereegranskat)abstract
    • Identifying brain systems that regulate or modulate autonomic nervous system functions may identify pathways through which psychosocial factors can influence health and disease. Reduced high-frequency heart rate variability (HF-HRV) characterizes anxiety disordered patients and is predictive of adverse myocardial events. Sex differences in the prevalence of anxiety disorders and cardiac diseases implicate the possibility of sex specific neural regulation of HF-HRV. We investigated the correlation between HF-HRV and regional cerebral blood flow (rCBF) in 28 subjects (15 women) with social phobia undergoing a stressful public speaking task. Regional CBF was measured with [(15)O] water positron emission tomography. Stress induced rCBF correlated positively with HF-HRV in the right supra genual anterior cingulate cortex Brodmann's area (BA) 32, the right head of the caudate nucleus and bilaterally in the medial prefrontal cortex (BA10), extending into the dorsolateral prefrontal cortex (BA46) in the left hemisphere. Men showed larger positive co-variation in the caudate than women. These findings underscore the importance of the emotional division of the anterior cingulate cortex, the prefrontal cortex and the striatum in cardiovagal activity. The study replicates and extends results from published functional neuroimaging studies on cardioregulatory or modulatory areas in healthy subjects to men and women with social phobia. Moreover, caudate functions, possibly related to dopaminergic neurotransmission, have sexually dimorphic effects on vagal modulation of the heart.
  •  
7.
  • Akram, Harith, et al. (författare)
  • Subthalamic deep brain stimulation sweet spots and hyperdirect cortical connectivity in Parkinson's disease
  • 2017
  • Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 158, s. 332-345
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: Firstly, to identify subthalamic region stimulation clusters that predict maximum improvement in rigidity, bradykinesia and tremor, or emergence of side-effects; and secondly, to map-out the cortical fingerprint, mediated by the hyperdirect pathways which predict maximum efficacy.Methods: High angular resolution diffusion imaging in twenty patients with advanced Parkinson's disease was acquired prior to bilateral subthalamic nucleus deep brain stimulation. All contacts were screened one-year from surgery for efficacy and side-effects at different amplitudes. Voxel-based statistical analysis of volumes of tissue activated models was used to identify significant treatment clusters. Probabilistic tractography was employed to identify cortical connectivity patterns associated with treatment efficacy.Results: All patients responded well to treatment (46% mean improvement off medication UPDRS-III [p < 0.0001]) without significant adverse events. Cluster corresponding to maximum improvement in tremor was in the posterior, superior and lateral portion of the nucleus. Clusters corresponding to improvement in bradykinesia and rigidity were nearer the superior border in a further medial and posterior location. The rigidity cluster extended beyond the superior border to the area of the zona incerta and Forel-H-2 field. When the clusters where averaged, the coordinates of the area with maximum overall efficacy was X = -10(-9.5), Y = -3(-1) and Z = -7(-3) in MNI(AC-PC) space. Cortical connectivity to primary motor area was predictive of higher improvement in tremor; whilst that to supplementary motor area was predictive of improvement in bradykinesia and rigidity; and connectivity to prefrontal cortex was predictive of improvement in rigidity.Interpretation: These findings support the presence of overlapping stimulation sites within the subthalamic nucleus and its superior border, with different cortical connectivity patterns, associated with maximum improvement in tremor, rigidity and bradykinesia.
  •  
8.
  •  
9.
  •  
10.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 477
Typ av publikation
tidskriftsartikel (394)
konferensbidrag (78)
forskningsöversikt (5)
Typ av innehåll
refereegranskat (391)
övrigt vetenskapligt/konstnärligt (86)
Författare/redaktör
Halldin, C (79)
Farde, L (50)
Gulyas, B (44)
Varrone, A (26)
Petersson, KM (23)
Ingvar, M (17)
visa fler...
Bäckman, Lars (17)
Fransson, P. (15)
Szczepankiewicz, Fil ... (15)
Nilsson, Markus (15)
Pike, VW (14)
Nyberg, Lars (13)
Farde, Lars (12)
Savic, I (11)
Karlsson, P (11)
Cselenyi, Z (11)
Oostenveld, R (11)
Salami, Alireza (11)
van Westen, Danielle (10)
Cervenka, Simon (10)
Seneca, N (10)
Takano, A (10)
Olsson, H. (9)
Halldin, Christer (9)
Westin, Carl-Fredrik (9)
Kalpouzos, Grégoria (9)
Andersson, J (8)
Finnema, SJ (8)
Mårtensson, Johan (8)
Radua, J (7)
Helms, Gunther (7)
Schou, M (7)
Rieckmann, Anna (7)
Ullen, F (7)
Syvänen, Stina (7)
Brehmer, Yvonne (7)
Agartz, I (6)
Wahlund, Lars-Olof (6)
Wahlund, LO (6)
Ito, H. (6)
Weiskopf, Nikolaus (6)
Andersson, Micael (6)
Knutsson, Hans (6)
Özarslan, Evren (6)
Hall, H (6)
Varnas, K (6)
Ashburner, John (6)
Lundqvist, D (6)
Finnema, S (6)
Toth, M (6)
visa färre...
Lärosäte
Karolinska Institutet (329)
Lunds universitet (62)
Uppsala universitet (51)
Stockholms universitet (51)
Umeå universitet (43)
Linköpings universitet (37)
visa fler...
Göteborgs universitet (25)
Kungliga Tekniska Högskolan (6)
Örebro universitet (6)
Högskolan Kristianstad (4)
Högskolan i Skövde (4)
Chalmers tekniska högskola (4)
Mittuniversitetet (2)
Gymnastik- och idrottshögskolan (2)
Mälardalens universitet (1)
Handelshögskolan i Stockholm (1)
RISE (1)
visa färre...
Språk
Engelska (477)
Forskningsämne (UKÄ/SCB)
Medicin och hälsovetenskap (173)
Samhällsvetenskap (43)
Teknik (28)
Naturvetenskap (27)
Humaniora (1)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy