Functional Anatomy of Intensity Aspects of Attention

2003 ◽  
Vol 14 (3) ◽  
pp. 181-190 ◽  
Author(s):  
Walter Sturm
Keyword(s):  
Right Hemisphere ◽  
Functional Anatomy ◽  
Fmri Data ◽  
Functional Networks ◽  
Top Down ◽  
Stimulus Modality ◽  
Spatial Orienting ◽  
Phasic Alertness ◽  
Co Activation ◽  
Attention System

Abstract: Behavioral and PET/fMRI-data are presented to delineate the functional networks subserving alertness, sustained attention, and vigilance as different aspects of attention intensity. The data suggest that a mostly right-hemisphere frontal, parietal, thalamic, and brainstem network plays an important role in the regulation of attention intensity, irrespective of stimulus modality. Under conditions of phasic alertness there is less right frontal activation reflecting a diminished need for top-down regulation with phasic extrinsic stimulation. Furthermore, a high overlap between the functional networks for alerting and spatial orienting of attention is demonstrated. These findings support the hypothesis of a co-activation of the posterior attention system involved in spatial orienting by the anterior alerting network. Possible implications of these findings for the therapy of neglect are proposed.

A fronto-insular-parietal network for the sense of body ownership

2021 ◽  
Author(s):  
Valentina Moro ◽  
Valentina Pacella ◽  
Michele Scandola ◽  
Sahba Besharati ◽  
Elena Rossato ◽  
...  
Keyword(s):  
Multisensory Integration ◽  
Right Hemisphere ◽  
Small Sample ◽  
Functional Networks ◽  
Body Ownership ◽  
The Novel ◽  
Cortical Lesions ◽  
Top Down ◽  
Lesion Analysis ◽  
Supporting Functional

Abstract Neuropsychological disturbances in the sense of limb ownership (DSO) provide a unique opportunity to study the neurocognitive basis of the sense of body ownership. Previous small sample studies focused on discrete cortical lesions and modular accounts, which cannot explain the modulations of DSO by multisensory, affective and cognitive manipulations. We tested the novel hypothesis that DSO would be associated not only with discrete cortical lesions, but also with disconnections of frontoparietal and fronto-insular white-matter tracts, supporting functional networks for multisensory integration and salience monitoring. To overcome the aforementioned methodological limitations, we drew on an advanced, probabilistic lesion-analysis and Bayesian statistics approach and tested this hypothesis in 49 right-hemisphere patients. Our results reveal that, as predicted, DSO is associated with lesions and disconnections of a fronto-insular-parietal network, suggesting that the sense of body ownership involves the convergence between bottom-up processes of multisensory integration and top-down control and monitoring of sensory salience.

Functional anatomy of the human auditory attention system

NeuroImage ◽  
1996 ◽  
Vol 3 (3) ◽  
pp. S200 ◽  
Author(s):  
N. Tzourio ◽  
F. El Massioui ◽  
B. Renault ◽  
B. Mazoyer
Keyword(s):  
Functional Anatomy ◽  
Auditory Attention ◽  
Attention System

scholarly journals Estimating dynamic brain functional networks using multi-subject fMRI data

NeuroImage ◽  
2018 ◽  
Vol 183 ◽  
pp. 635-649 ◽  
Author(s):  
Suprateek Kundu ◽  
Jin Ming ◽  
Jordan Pierce ◽  
Jennifer McDowell ◽  
Ying Guo
Keyword(s):  
Fmri Data ◽  
Functional Networks ◽  
Brain Functional Networks

Redeployed functions versus spreading activation: A potential confound

2010 ◽  
Vol 33 (4) ◽  
pp. 280-281 ◽  
Author(s):  
Colin Klein
Keyword(s):  
Information Processing ◽  
Meta Analysis ◽  
Fmri Data ◽  
Functional Networks ◽  
Spreading Activation ◽  
Adaptation Studies ◽  
Per Se ◽  
Fmri Adaptation ◽  
Potential Confound

AbstractAnderson's meta-analysis of fMRI data is subject to a potential confound. Areas identified as active may make no functional contribution to the task being studied, or may indicate regions involved in the coordination of functional networks rather than information processing per se. I suggest a way in which fMRI adaptation studies might provide a useful test between these alternatives.

scholarly journals Select and Cluster: A Method for Finding Functional Networks of Clustered Voxels in fMRI

2016 ◽  
Vol 2016 ◽  
pp. 1-19 ◽  
Author(s):  
Danilo DonGiovanni ◽  
Lucia Maria Vaina
Keyword(s):  
Functional Connectivity ◽  
A Priori ◽  
Data Driven ◽  
Fmri Data ◽  
Support Vector ◽  
Functional Networks ◽  
Compact Groups ◽  
Mutual Correlation ◽  
Pairwise Correlation ◽  
Vector Clustering

Extracting functional connectivity patterns among cortical regions in fMRI datasets is a challenge stimulating the development of effective data-driven or model based techniques. Here, we present a novel data-driven method for the extraction of significantly connected functional ROIs directly from the preprocessed fMRI data without relying on a priori knowledge of the expected activations. This method finds spatially compact groups of voxels which show a homogeneous pattern of significant connectivity with other regions in the brain. The method, called Select and Cluster (S&C), consists of two steps: first, a dimensionality reduction step based on a blind multiresolution pairwise correlation by which the subset of all cortical voxels with significant mutual correlation is selected and the second step in which the selected voxels are grouped into spatially compact and functionally homogeneous ROIs by means of a Support Vector Clustering (SVC) algorithm. The S&C method is described in detail. Its performance assessed on simulated and experimental fMRI data is compared to other methods commonly used in functional connectivity analyses, such as Independent Component Analysis (ICA) or clustering. S&C method simplifies the extraction of functional networks in fMRI by identifying automatically spatially compact groups of voxels (ROIs) involved in whole brain scale activation networks.

Dishabituation of Laser-evoked EEG Responses: Dissecting the Effect of Certain and Uncertain Changes in Stimulus Modality

2011 ◽  
Vol 23 (10) ◽  
pp. 2822-2837 ◽  
Author(s):  
Elia Valentini ◽  
Diana M. E. Torta ◽  
André Mouraux ◽  
Gian Domenico Iannetti
Keyword(s):  
Explicit Knowledge ◽  
Sensory Modality ◽  
The Other ◽  
Subjective Perception ◽  
Top Down ◽  
Stimulus Modality ◽  
Bottom Up ◽  
Relative Contribution ◽  
Brain Responses ◽  
Response Habituation

The repetition of nociceptive stimuli of identical modality, intensity, and location at short and constant interstimulus intervals (ISIs) determines a strong habituation of the corresponding EEG responses, without affecting the subjective perception of pain. To understand what determines this response habituation, we (i) examined the effect of introducing a change in the modality of the repeated stimulus, and (ii) dissected the relative contribution of bottom–up, stimulus-driven changes in modality and top–down, cognitive expectations of such a change, on both laser-evoked and auditory-evoked EEG responses. Multichannel EEG was recorded while participants received trains of three stimuli (S1–S2–S3, a triplet) delivered to the hand dorsum at 1-sec ISI. S3 belonged either to the same modality as S1 and S2 or to the other modality. In addition, participants were either explicitly informed or not informed of the modality of S3. We found that introducing a change in stimulus modality produced a significant dishabituation of the laser-evoked N1, N2, and P2 waves; the auditory N1 and P2 waves; and the laser- and auditory-induced event-related synchronization and desynchronization. In contrast, the lack of explicit knowledge of a possible change in the sensory modality of the stimulus (i.e., uncertainty) only increased the ascending portion of the laser-evoked and auditory-evoked P2 wave. Altogether, these results indicate that bottom–up novelty resulting from the change of stimulus modality, and not top–down cognitive expectations, plays a major role in determining the habituation of these brain responses.

scholarly journals Effects of rTMS Conditioning over the Fronto-parietal Network on Motor versus Visual Attention

2007 ◽  
Vol 19 (3) ◽  
pp. 513-524 ◽  
Author(s):  
Elisabeth Rounis ◽  
Kielan Yarrow ◽  
John C. Rothwell
Keyword(s):  
Visual Attention ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Preparation ◽  
Attention Task ◽  
Spatial Orienting ◽  
Left Dlpfc ◽  
The Right

Many studies have shown that visuospatial orienting attention depends on a network of frontal and parietal areas in the right hemisphere. Rushworth et al. [Rushworth, M. F., Krams, M., & Passingham, R. E. The attentional role of the left parietal cortex: The distinct lateralization and localization of motor attention in the human brain. Journal of Cognitive Neuroscience, 13, 698–710, 2001] have recently provided evidence for a left-lateralized network of parietal areas involved in motor attention. Using two variants of a cued reaction time (RT) task, we set out to investigate whether high-frequency repetitive transcranial magnetic stimulation (rTMS; 5 Hz) delivered “off-line” in a virtual lesion paradigm over the right or left dorsolateral prefrontal cortex (DLPFC) or the posterior parietal cortex (PPC) would affect performance in a motor versus a visual attention task. Although rTMS over the DLPFC on either side did not affect RT performance on a spatial orienting task, it did lead to an increase in the RTs of invalidly cued trials in a motor attention task when delivered to the left DLPFC. The opposite effect was found when rTMS was delivered to the PPC: In this case, conditioning the right PPC led to increased RTs in invalidly cued trials located in the left hemispace, in the spatial orienting task. rTMS over the PPC on either side did not affect performance in the motor attention task. This double dissociation was evident in the first 10 min after rTMS conditioning. These results enhance our understanding of the networks associated with attention. They provide evidence of a role for the left DLPFC in the mechanisms of motor preparation, and confirm Mesulam's original proposal for a right PPC dominance in spatial attention [Mesulam, M. M. A cortical network for directed attention and unilateral neglect. Annals of Neurology, 10, 309–325, 1981].

scholarly journals On the role of the ventral attention system in spatial orienting

2014 ◽  
Vol 8 ◽  
Author(s):  
Ana B. Chica ◽  
Alexia Bourgeois ◽  
Paolo Bartolomeo
Keyword(s):  
Spatial Orienting ◽  
Attention System

scholarly journals Nonlinear Functional Network Connectivity In Resting fMRI Data

2021 ◽  
Author(s):  
Sara Motlaghian ◽  
Aysenil Belger ◽  
Juan Bustillo ◽  
Judith Ford ◽  
Kelvin Lim ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Group Analysis ◽  
Nonlinear Effects ◽  
Brain Regions ◽  
Fmri Data ◽  
Functional Networks ◽  
Healthy Controls ◽  
Normalized Mutual Information ◽  
Linear Approach ◽  
Linear And Nonlinear

In this work, we focus on explicitly nonlinear relationships in functional networks. We introduce a technique using normalized mutual information (MI), that calculates the nonlinear correlation between different brain regions. We demonstrate our proposed approach using simulated data, then apply it to a dataset previously studied in (Damaraju et al., 2014). This resting-state fMRI data included 151 schizophrenia patients and 163 age- and gender-matched healthy controls. We first decomposed these data using group independent component analysis (ICA) and yielded 47 functionally relevant intrinsic connectivity networks. Our analysis showed a modularized 2 nonlinear relationship among brain functional networks that was particularly noticeable in the sensory and visual cortex. Interestingly, the modularity appears both meaningful and distinct from that revealed by the linear approach. Group analysis identified significant differences in nonlinear dependencies between schizophrenia patients and healthy controls particularly in visual cortex, with controls showing more nonlinearity in most cases. Certain domains, including cognitive control, and default mode, appeared much less nonlinear, whereas links between the visual and other domains showed evidence of substantial nonlinear and modular properties. Overall, these results suggest that quantifying nonlinear dependencies of functional connectivity may provide a complementary and potentially important tool for studying brain function by exposing relevant variation that is typically ignored. Further, we propose a method that captures both linear and nonlinear effects in a 'boosted' approach. This method increases the sensitivity to group differences in comparison to the standard linear approach, at the cost of being unable to separate linear and nonlinear effects.

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