scholarly journals Hemispheric Differences in the Voluntary Control of Spatial Attention: Direct Evidence for a Right-Hemispheric Dominance within Frontal Cortex

2013 ◽  
Vol 25 (8) ◽  
pp. 1332-1342 ◽  
Author(s):  
Felix Duecker ◽  
Elia Formisano ◽  
Alexander T. Sack
Keyword(s):  
Frontal Cortex ◽  
Spatial Attention ◽  
Direct Evidence ◽  
Functional Asymmetry ◽  
Hemispheric Dominance ◽  
Hemispheric Differences ◽  
Attentional Processes ◽  
Frontoparietal Network ◽  
Competing Models ◽  
The Right

Lesion studies in neglect patients have inspired two competing models of spatial attention control, namely, Heilman's “hemispatial” theory and Kinsbourne's “opponent processor” model. Both assume a functional asymmetry between the two hemispheres but propose very different mechanisms. Neuroimaging studies have identified a bilateral dorsal frontoparietal network underlying voluntary shifts of spatial attention. However, lateralization of attentional processes within this network has not been consistently reported. In the current study, we aimed to provide direct evidence concerning the functional asymmetry of the right and left FEF during voluntary shifts of spatial attention. To this end, we applied fMRI-guided neuronavigation to disrupt individual FEF activation foci with a longer-lasting inhibitory patterned TMS protocol followed by a spatial cueing task. Our results indicate that right FEF stimulation impaired the ability of shifting spatial attention toward both hemifields, whereas the effects of left FEF stimulation were limited to the contralateral hemifield. These results provide strong direct evidence for right-hemispheric dominance in spatial attention within frontal cortex supporting Heilman's “hemispatial” theory. This complements previous TMS studies that generally conform to Kinsbourne's “opponent processor” model after disruption of parietal cortex, and we therefore propose that both theories are not mutually exclusive.

scholarly journals Atypical Hemispheric Dominance for Attention: Functional MRI Topography

2005 ◽  
Vol 25 (9) ◽  
pp. 1197-1208 ◽  
Author(s):  
Agnes Flöel ◽  
Andreas Jansen ◽  
Michael Deppe ◽  
Martin Kanowski ◽  
Carsten Konrad ◽  
...  
Keyword(s):  
Spatial Attention ◽  
Right Hemisphere ◽  
Regional Distribution ◽  
Visuospatial Attention ◽  
Hemispheric Dominance ◽  
Neural Activation ◽  
Brain Organization ◽  
Attention Task ◽  
Control Subjects ◽  
The Right

The right hemisphere is predominantly involved in tasks associated with spatial attention. However, left hemispheric dominance for spatial attention can be found in healthy individuals, and both spatial attention and language can be lateralized to the same hemisphere. Little is known about the underlying regional distribution of neural activation in these ‘atypical’ individuals. Previously a large number of healthy subjects were screened for hemispheric dominance of visuospatial attention and language, using functional Doppler ultrasonography. From this group, subjects were chosen who were ‘atypical’ for hemispheric dominance of visuospatial attention and language, and their pattern of brain activation was studied with functional magnetic resonance imaging during a task probing spatial attention. Right-handed subjects with the ‘typical’ pattern of brain organization served as control subjects. It was found that subjects with an inverted lateralization of language and spatial attention (language right, attention left) recruited left-hemispheric areas in the attention task, homotopic to those recruited by control subjects in the right hemisphere. Subjects with lateralization of both language and attention to the right hemisphere activated an attentional network in the right hemisphere that was comparable to control subjects. The present findings suggest that not the hemispheric side, but the intrahemispheric pattern of activation is the distinct feature for the neural processes underlying language and attention.

Brain Networks Related to Beta Oscillatory Activity during Episodic Memory Retrieval

2018 ◽  
Vol 30 (2) ◽  
pp. 174-187 ◽  
Author(s):  
Erika Nyhus
Keyword(s):  
Frontal Cortex ◽  
Oscillatory Activity ◽  
Episodic Retrieval ◽  
Beta Oscillations ◽  
New Words ◽  
Memory Suppression ◽  
Frontoparietal Network ◽  
Beta Power ◽  
Place Task ◽  
The Right

Evidence from fMRI has consistently located a widespread network of frontal, parietal, and temporal lobe regions during episodic retrieval. However, the temporal limitations of the fMRI methodology have made it difficult to assess the transient network dynamics by which these distributed regions coordinate activity. Recent evidence suggests that beta oscillations (17–20 Hz) are important for top–down control for memory suppression. However, the spatial limitations of the EEG methodology make it difficult to assess the relationship between these oscillatory signals and the distributed networks identified with fMRI. This study used simultaneous EEG/fMRI to identify networks related to beta oscillations during episodic retrieval. Participants studied adjectives and either imagined a scene (Place Task) or judged its pleasantness (Pleasant Task). During the recognition test, participants decided which task was performed with each word (“Old Place Task” or “Old Pleasant Task”) or “New.” EEG results revealed that posterior beta power was greater for new than old words. fMRI results revealed activity in a frontal, parietal network that was greater for old than new words, consistent with prior studies. Although overall beta power increases correlated with decreased activity within a predominantly parietal network, within the right dorsolateral and ventrolateral pFC, beta power correlated with BOLD activity more under conditions requiring more cognitive control and EEG/fMRI effects in the right frontal cortex correlated with BOLD activity in a frontoparietal network. Therefore, using simultaneous EEG and fMRI, the present results suggest that beta oscillations are related to postretrieval control operations in the right frontal cortex and act within a broader postretrieval control network.

scholarly journals Cerebral Hemispheric Dominance and Lateralization. Examination methods and procedures

2021 ◽  
Vol VII (2) ◽  
pp. 67-84
Author(s):  
Vasile Radu PREDA
Keyword(s):  
Right Hemisphere ◽  
Functional Asymmetry ◽  
Cerebral Hemispheres ◽  
Hemispheric Dominance ◽  
Cortical Level ◽  
Combined Use ◽  
Examination Methods ◽  
The Right ◽  
Behavioural Function ◽  
Neuropsychological Investigations

On the basis of electrophysiological and neuropsychological investigations the existence of cerebral hemispheric dominance has been established. Thus, a certain psycho-behavioural function may not be equally governed by either the left or the right hemisphere, a tendency towards lateralization coming into play (Sperri, 1974; Arseni, Golu, Dănăilă, 1983; Funnell, Carballis, Gazzanga, 2000). The functional asymmetry of the analysers is encountered both at the peripheral level, through the sensory-motor lateralization of paired receptors, and at the cortical level, through the asymmetrical functioning of the cerebral hemispheres. Consequently, tests for hemispheric dominance, as well as tests for lateralization must, respectively, be employed. When examining cerebral hemispheric dominance and lateralization, the characteristics of the organs under investigation are taken into account, and so is the age of the subjects. The examination of functional asymmetry in the case of analyzers with paired receptors has relied on an impressive number of trials, procedures, tests and questionnaires on lateralization, all suitable for the subjects’ age and for the psycho-physiological characteristics of the respective couple of paired organs. The combined use of lateralization tests specifically adapted for all paired organs (hand, eye, is essential in order to establish the degree of lateralization homogeneity. The examinations and the calculation of the laterality index are to be done periodically, the results being recorded in a chart that reflects the evolution of lateralization as a result of engaging the child in various activities meant for a specific type of lateralization.

Extinguishing Extinction: Hemispheric Differences in the Modulation of TMS-induced Visual Extinction by Directing Covert Spatial Attention

2012 ◽  
Vol 24 (4) ◽  
pp. 809-818 ◽  
Author(s):  
Nina Bien ◽  
Rainer Goebel ◽  
Alexander T. Sack
Keyword(s):  
Spatial Attention ◽  
Cognitive Neuroscience ◽  
Early Stage ◽  
Hemispheric Lateralization ◽  
Hemispheric Differences ◽  
Behavioral Deficits ◽  
Stage Of Development ◽  
Great Relevance ◽  
Left And Right ◽  
The Right

The topic of spatial attention is of great relevance for researchers in various fields, including neuropsychology, cognitive neuroscience, and cognitive psychology, as well as for clinical practice. Deficits of spatial attentional arising from parietal brain damage remain largely confined to the left visual field. The mechanisms underlying this hemispheric asymmetry are still elusive. We mimicked the neuropsychological syndrome of contralesional extinction by temporarily inducing a spatial attentional bias in healthy volunteers with TMS. We investigated whether directing covert spatial attention could enhance or, more importantly, counteract the resulting behavioral deficits. Although both the left and right parietal TMS induced contralateral extinction, only left hemifield extinction following right parietal TMS was severely aggravated by a competing stimulus in the ipsilesional (right) hemifield. We put forward the hypothesis that an asymmetry with respect to the ability of detaching attention from a distractor is contributing to the right hemispheric lateralization with regard to extinction. On a broader level, we suggest that “virtual patients” might be used for evaluating neuropsychological treatment in an early stage of development, reducing the burden on actual patients.

Individual Differences and Hemispheric Asymmetry While Processing Emotional Words

2014 ◽  
Vol 35 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Lindsay M. Niccolai ◽  
Thomas Holtgraves
Keyword(s):  
Individual Differences ◽  
Hemispheric Asymmetry ◽  
Past Research ◽  
Decision Task ◽  
Depression And Anxiety ◽  
Hemispheric Differences ◽  
Affective Valence ◽  
Emotional Words ◽  
Emotion Words ◽  
The Right

This research examined differences in the perception of emotion words as a function of individual differences in subclinical levels of depression and anxiety. Participants completed measures of depression and anxiety and performed a lexical decision task for words varying in affective valence (but equated for arousal) that were presented briefly to the right or left visual field. Participants with a lower level of depression demonstrated hemispheric asymmetry with a bias toward words presented to the left hemisphere, but participants with a higher level of depression displayed no hemispheric differences. Participants with a lower level of depression also demonstrated a bias toward positive words, a pattern that did not occur for participants with a higher level of depression. A similar pattern occurred for anxiety. Overall, this study demonstrates how variability in levels of depression and anxiety can influence the perception of emotion words, with patterns that are consistent with past research.

scholarly journals Perceiving numerosity does not cause automatic shifts of spatial attention

2021 ◽  
Author(s):  
Michele Pellegrino ◽  
Mario Pinto ◽  
Fabio Marson ◽  
Stefano Lasaponara ◽  
Fabrizio Doricchi
Keyword(s):  
Spatial Attention ◽  
Colour Change ◽  
Simultaneous Presentation ◽  
Variable Delay ◽  
Large Magnitude ◽  
Small Magnitude ◽  
Spatial Component ◽  
Speed Up ◽  
The Right

AbstractIt is debated whether the representation of numbers is endowed with a directional-spatial component so that perceiving small-magnitude numbers triggers leftward shifts of attention and perceiving large-magnitude numbers rightward shifts. Contrary to initial findings, recent investigations have demonstrated that centrally presented small-magnitude and large-magnitude Arabic numbers do not cause leftward and rightward shifts of attention, respectively. Here we verified whether perceiving small or large non-symbolic numerosities (i.e., clouds of dots) drives attention to the left or the right side of space, respectively. In experiment 1, participants were presented with central small (1, 2) vs large-numerosity (8, 9) clouds of dots followed by an imperative target in the left or right side of space. In experiment 2, a central cloud of dots (i.e., five dots) was followed by the simultaneous presentation of two identical dot-clouds, one on the left and one on the right side of space. Lateral clouds were both lower (1, 2) or higher in numerosity (8, 9) than the central cloud. After a variable delay, one of the two lateral clouds turned red and participants had to signal the colour change through a unimanual response. We found that (a) in Experiment 1, the small vs large numerosity of the central cloud of dots did not speed up the detection of left vs right targets, respectively, (b) in Experiment 2, the detection of colour change was not faster in the left side of space when lateral clouds were smaller in numerosity than the central reference and in the right side when clouds were larger in numerosity. These findings show that perceiving non-symbolic numerosity does not cause automatic shifts of spatial attention and suggests no inherent association between the representation of numerosity and that of directional space.

scholarly journals When brain damage “improves” perception: neglect patients can localize motion-shifted probes better than controls

2015 ◽  
Vol 114 (6) ◽  
pp. 3351-3358 ◽  
Author(s):  
Stefania de Vito ◽  
Marine Lunven ◽  
Clémence Bourlon ◽  
Christophe Duret ◽  
Patrick Cavanagh ◽  
...  
Keyword(s):  
Right Hemisphere ◽  
Visual Fields ◽  
Critical Factor ◽  
Significant Shift ◽  
Stimulus Motion ◽  
Attentional Processes ◽  
Position Shift ◽  
The Right ◽  
High Level ◽  
Better Than

When we look at bars flashed against a moving background, we see them displaced in the direction of the upcoming motion (flash-grab illusion). It is still debated whether these motion-induced position shifts are low-level, reflexive consequences of stimulus motion or high-level compensation engaged only when the stimulus is tracked with attention. To investigate whether attention is a causal factor for this striking illusory position shift, we evaluated the flash-grab illusion in six patients with damaged attentional networks in the right hemisphere and signs of left visual neglect and six age-matched controls. With stimuli in the top, right, and bottom visual fields, neglect patients experienced the same amount of illusion as controls. However, patients showed no significant shift when the test was presented in their left hemifield, despite having equally precise judgments. Thus, paradoxically, neglect patients perceived the position of the flash more veridically in their neglected hemifield. These results suggest that impaired attentional processes can reduce the interaction between a moving background and a superimposed stationary flash, and indicate that attention is a critical factor in generating the illusory motion-induced shifts of location.

Abstract 15570: Direct Evidence of Endo-Epicardial Dissociation of the Atrial Wall in Patients With Longstanding Persistent Atrial Fibrillation

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Natasja de Groot ◽  
Lisette vd Does ◽  
Ameeta Yaksh ◽  
Paul Knops ◽  
Pieter Woestijne ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Direct Evidence ◽  
Persistent Atrial Fibrillation ◽  
Right Atrial ◽  
Electrode Arrays ◽  
Atrial Wall ◽  
Ablative Therapies ◽  
Epicardial Layer ◽  
Right Atrial Appendage ◽  
The Right

Introduction: Transition of paroxysmal to longstanding persistent atrial fibrillation (LsPAF) is associated with progressive longitudinal dissociation in conduction and a higher incidence of focal fibrillation waves. The aim of this study was to provide direct evidence that the substrate of LsPAF consists of an electrical double-layer of dissociated waves, and that focal fibrillation waves are caused by endo-epicardial breakthrough. Hypothesis: LsPAF in humans is caused by electrical dissociation of the endo- and epicardial layer. Methods: Intra-operative mapping of the endo- and epicardial right atrial wall was performed in 9 patients with induced (N=4), paroxysmal (N=1), persistent (N=2) or longstanding-persistent AF (N=2). A clamp of two rectangular electrode-arrays (128 electrodes; inter-electrode distance 2mm) was introduced through an incision in the right atrial appendage. Series of 10 seconds of AF were analyzed and the incidence of endo-epicardial dissociation (≥15ms) was determined for all 128 endo-epicardial recording sites. Results: In patients with LsPAF the averaged degree of endo-epicardial dissociation was highest (24.9% vs. 5.9%). Using strict criteria for breakthrough (presence of an opposite wave within 4mm and <15ms before the origin of the focal wave), the far majority (77%) of all focal fibrillation waves could be attributed to endo-epicardial excitation. Conclusions: During LsPAF considerable differences in activation of the right endo- and epicardial wall exist. Endo-epicardial fibrillation waves that are out of phase, may conduct transmurally and create breakthrough waves in the opposite layer. This may explain the high persistence of AF and the low succes rate of ablative therapies in patients with LsPAF.

scholarly journals Decreased event-related theta power and phase-synchrony in young binge drinkers during target detection: An anatomically-constrained MEG approach

2018 ◽  
Vol 33 (3) ◽  
pp. 335-346 ◽  
Author(s):  
A Correas ◽  
E López-Caneda ◽  
L Beaton ◽  
S Rodríguez Holguín ◽  
LM García-Moreno ◽  
...  
Keyword(s):  
Alcohol Consumption ◽  
Frontal Cortex ◽  
Binge Drinking ◽  
Target Detection ◽  
Attentional Control ◽  
Theta Power ◽  
Inferior Frontal Cortex ◽  
Binge Drinkers ◽  
The Right ◽  
Integrative Processing

Background: The prevalence of binge drinking has risen in recent years. It is associated with a range of neurocognitive deficits among adolescents and young emerging adults who are especially vulnerable to alcohol use. Attention is an essential dimension of executive functioning and attentional disturbances may be associated with hazardous drinking. The aim of the study was to examine the oscillatory neural dynamics of attentional control during visual target detection in emerging young adults as a function of binge drinking. Method: In total, 51 first-year university students (18 ± 0.6 years) were assigned to light drinking ( n = 26), and binge drinking ( n = 25) groups based on their alcohol consumption patterns. A high-density magnetoencephalography signal was combined with structural magnetic resonance imaging in an anatomically constrained magnetoencephalography model to estimate event-related source power in a theta (4–7 Hz) frequency band. Phase-locked co-oscillations were further estimated between the principally activated regions during task performance. Results: Overall, the greatest event-related theta power was elicited by targets in the right inferior frontal cortex and it correlated with performance accuracy and selective attention scores. Binge drinkers exhibited lower theta power and dysregulated oscillatory synchrony to targets in the right inferior frontal cortex, which correlated with higher levels of alcohol consumption. Conclusions: These results confirm that a highly interactive network in the right inferior frontal cortex subserves attentional control, revealing the importance of theta oscillations and neural synchrony for attentional capture and contextual maintenance. Attenuation of theta power and synchronous interactions in binge drinkers may indicate early stages of suboptimal integrative processing in young, highly functioning binge drinkers.

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