scholarly journals Callosal anisotropy predicts attentional network changes after parietal inhibitory stimulation

2020 ◽  
Author(s):  
Selene Schintu ◽  
Catherine A. Cunningham ◽  
Michael Freedberg ◽  
Paul Taylor ◽  
Stephen J. Gotts ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Superior Temporal Gyrus ◽  
Resting State Functional Connectivity ◽  
Local Inhibition ◽  
Frontoparietal Network ◽  
Attentional Network ◽  
Posterior Parietal ◽  
Neuropsychological Evidence ◽  
The Right

AbstractHemispatial neglect is thought to result from disruption of interhemispheric equilibrium. Right hemisphere lesions deactivate the right frontoparietal network and hyperactivate the left via release from interhemispheric inhibition. Support for this theory comes from neuropsychological evidence as well as transcranial magnetic stimulation (TMS) studies in healthy subjects, in whom right posterior parietal cortex (PPC) inhibition causes neglect-like, rightward, visuospatial bias. Concurrent TMS and fMRI after right PPC TMS show task-dependent changes but may fail to identify effects of stimulation in areas not directly activated by the specific task, complicating interpretations. We used resting-state functional connectivity (RSFC) after inhibitory TMS over the right PPC to examine changes in the networks underlying visuospatial attention.In a crossover experiment in healthy individuals, we delivered continuous theta burst TMS to the right PPC and vertex as control condition. We hypothesized that PPC inhibitory stimulation would cause a rightward visuospatial bias, decrease PPC connectivity with frontal areas, and increase PPC connectivity with the attentional network in the left hemisphere. We also expected that individual differences in fractional anisotropy (FA) in white matter connections between the PPCs would account for variability in TMS-induced RSFC changes.As expected, TMS over the right PPC caused a rightward shift in line bisection judgment and increased RSFC between the right PPC and the left superior temporal gyrus. This effect was inversely related to FA in the posterior corpus callosum. Local inhibition of the right PPC reshapes connectivity in the attentional network and depends on interhemispheric connections.

scholarly journals Prism Adaptation Modulates Connectivity of the Intraparietal Sulcus with Multiple Brain Networks

2020 ◽  
Vol 30 (9) ◽  
pp. 4747-4758 ◽  
Author(s):  
Selene Schintu ◽  
Michael Freedberg ◽  
Stephen J Gotts ◽  
Catherine A Cunningham ◽  
Zaynah M Alam ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Prism Adaptation ◽  
Healthy Individuals ◽  
Imaging Studies ◽  
Resting State Functional Connectivity ◽  
Frontoparietal Network ◽  
Before And After ◽  
Posterior Parietal ◽  
The Right

Abstract Prism adaptation (PA) alters spatial cognition according to the direction of visual displacement by temporarily modifying sensorimotor mapping. Right-shifting prisms (right PA) improve neglect of left visual field in patients, possibly by decreasing activity in the left hemisphere and increasing it in the right. Left PA shifts attention rightward in healthy individuals by an opposite mechanism. However, functional imaging studies of PA are inconsistent, perhaps because of differing activation tasks. We measured resting-state functional connectivity (RSFC) in healthy individuals before and after PA. When contrasted, right versus left PA decreased RSFC in the spatial navigation network defined by the right posterior parietal cortex (PPC), hippocampus, and cerebellum. Within-PA-direction comparisons showed that right PA increased RSFC in subregions of the PPCs and between the PPCs and the right middle frontal gyrus and left PA decreased RSFC between these regions. Both right and left PA decreased RSFC between the PPCs and bilateral temporal areas. In summary, right PA increases connectivity in the right frontoparietal network and left PA produces essentially opposite effects. Furthermore, right, compared with left, PA modulates RSFC in the right hemisphere navigation network.

scholarly journals Right lateralized posterior parietal theta-gamma coupling during sustained attention in mice

2020 ◽  
Author(s):  
Ryan Yang ◽  
Corrinne Dunbar ◽  
Alina Sonesra ◽  
Suhyeorn Park ◽  
Timothy Pham ◽  
...  
Keyword(s):  
Sustained Attention ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Reaction Time Task ◽  
Oscillatory Dynamics ◽  
Frontoparietal Network ◽  
Gamma Power ◽  
Posterior Parietal ◽  
Phase Amplitude ◽  
The Right

AbstractSustained attention is supported by circuits in the frontoparietal attention network. In human and primate studies, the right posterior parietal cortex (PPC) shows dominance for sustained attention, and phase-amplitude coupling (PAC) throughout the frontoparietal network correlates with performance on attention tasks. Here we evaluate oscillatory dynamics of bilateral PPC in mice during the 5-Choice Serial Reaction Time Task (5-CSRTT). Right PPC theta-gamma PAC (TG-PAC) and gamma power were independently elevated to a greater degree than the left PPC during the period prior to a correct response and were significantly correlated with accuracy in both simple and difficult tasks. Greater task difficulty was also associated with greater hemispheric asymmetry in TG-PAC, favoring the right PPC. These findings highlight the engagement of PPC with sustained attention in mice, reflected by increases in TG-PAC and gamma power, with maximal expression in the right hemisphere.

scholarly journals Paired-Pulse Parietal-Motor Stimulation Differentially Modulates Corticospinal Excitability across Hemispheres When Combined with Prism Adaptation

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Selene Schintu ◽  
Elisa Martín-Arévalo ◽  
Michael Vesia ◽  
Yves Rossetti ◽  
Romeo Salemme ◽  
...  
Keyword(s):  
Left Hemisphere ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Motor Evoked Potentials ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Prism Adaptation ◽  
Healthy Individuals ◽  
Paired Pulse ◽  
Posterior Parietal ◽  
The Right

Rightward prism adaptation ameliorates neglect symptoms while leftward prism adaptation (LPA) induces neglect-like biases in healthy individuals. Similarly, inhibitory repetitive transcranial magnetic stimulation (rTMS) on the right posterior parietal cortex (PPC) induces neglect-like behavior, whereas on the left PPC it ameliorates neglect symptoms and normalizes hyperexcitability of left hemisphere parietal-motor (PPC-M1) connectivity. Based on this analogy we hypothesized that LPA increases PPC-M1 excitability in the left hemisphere and decreases it in the right one. In an attempt to shed some light on the mechanisms underlying LPA’s effects on cognition, we investigated this hypothesis in healthy individuals measuring PPC-M1 excitability with dual-site paired-pulse TMS (ppTMS). We found a left hemisphere increase and a right hemisphere decrease in the amplitude of motor evoked potentials elicited by paired as well as single pulses on M1. While this could indicate that LPA biases interhemispheric connectivity, it contradicts previous evidence that M1-only MEPs are unchanged after LPA. A control experiment showed that input-output curves were not affected by LPAper se. We conclude that LPA combined with ppTMS on PPC-M1 differentially alters the excitability of the left and right M1.

scholarly journals Right-hemispheric dominance for visual remapping in humans

2011 ◽  
Vol 366 (1564) ◽  
pp. 572-585 ◽  
Author(s):  
L. Pisella ◽  
N. Alahyane ◽  
A. Blangero ◽  
F. Thery ◽  
S. Blanc ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Target Location ◽  
Original Data ◽  
Hemispheric Dominance ◽  
Cortical Lesion ◽  
Constructional Apraxia ◽  
Posterior Parietal ◽  
The Right ◽  
Transfer Of Information

We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms (intuitively related to remapping impairments) are observed in both neglect and constructional apraxia. More specifically, we review findings from the intervening saccade paradigm in humans—and present additional original data—which suggest a specific role of the asymmetrical network at the temporo-parietal junction (TPJ) in the right hemisphere in visual remapping: following damage to the right dorsal posterior parietal cortex (PPC) as well as part of the corpus callosum connecting the PPC to the frontal lobes, patient OK in a double-step saccadic task exhibited an impairment when the second saccade had to be directed rightward . This singular and lateralized deficit cannot result solely from the patient's cortical lesion and, therefore, we propose that it is due to his callosal lesion that may specifically interrupt the interhemispheric transfer of information necessary to execute accurate rightward saccades towards a remapped target location. This suggests a specialized right-hemispheric network for visuo-spatial remapping that subsequently transfers target location information to downstream planning regions, which are symmetrically organized.

scholarly journals Asymmetries in numerical density of pyramidal neurons in the fifth layer of the human posterior parietal cortex

2012 ◽  
Vol 69 (8) ◽  
pp. 681-685
Author(s):  
Natasa Djukic-Macut ◽  
Slobodan Malobabic ◽  
Natalija Stefanovic ◽  
Predrag Mandic ◽  
Tatjana Filipovic ◽  
...  
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Pyramidal Neurons ◽  
Right Hemisphere ◽  
Numerical Density ◽  
Group I ◽  
Posterior Parietal ◽  
Left And Right ◽  
Layer V ◽  
The Right

Background/Aim. Both superior parietal lobule (SPL) of dorsolateral hemispheric surface and precuneus (PEC) of medial surface are the parts of posterior parietal cortex. The aim of this study was to determine the numerical density (NV) of pyramidal neurons in the layer V of SPL and PEC and their potential differences. Methods. From 20 (40 hemispheres) formaline fixed human brains (both sexes; 27- 65 years) tissue blocks from SPL and PEC from the left and right hemisphere were used. According to their size the brains were divided into two groups, the group I with the larger left (15 brains) and the group II with the larger right hemisphere (5 brains). Serial Nissl sections (5 ?m) of the left and right SPL and PEC were used for stereological estimation of NV of the layer V pyramidal neurons. Results. NV of pyramidal neurons in the layer V in the left SPL of brains with larger left hemispheres was significantly higher than in the left SPL of brains with larger right hemisphere. Comparing sides in brains with larger left hemisphere, the left SPL had higher NV than the right one, and then the left PEC, and the right SPL had significantly higher NV than the right PEC. Comparing sides in brains with the larger right hemisphere, the left SPL had significantly higher NV than left PEC, but the right SPL had significantly higher NV than left SPL and the right PEC. Conclusion. Generally, there is an inverse relationship of NV between the medial and lateral areas of the human posterior parietal cortex. The obtained values were different between the brains with larger left and right hemispheres, as well as between the SPL and PEC. In all the comparisons the left SPL had the highest values of NV of pyramidal neurons in the layer V (4771.80 mm-3), except in brains with the larger right hemisphere.

scholarly journals Prism adaptation modulates connectivity of the intraparietal sulcus with multiple brain networks

2019 ◽  
Author(s):  
Selene Schintu ◽  
Michael Freedberg ◽  
Stephen J. Gotts ◽  
Catherine A. Cunningham ◽  
Zaynah M. Alam ◽  
...  
Keyword(s):  
Right Hemisphere ◽  
Prism Adaptation ◽  
Healthy Individuals ◽  
Resting State Functional Connectivity ◽  
Frontoparietal Network ◽  
Interhemispheric Competition ◽  
Before And After ◽  
And Shifts ◽  
The Right ◽  
Parietal Cortices

ABSTRACTPrism adaptation (PA) alters spatial cognition according to the direction of visual displacement by temporarily modifying sensorimotor mapping. Right-shifting prisms (right PA) improve neglect of left space in patients, possibly by decreasing activity in the left hemisphere and increasing it in the right. Left PA shifts attention to the right in healthy individuals by an opposite mechanism. However, functional imaging studies of PA are inconsistent, perhaps because of differing activation tasks. We measured resting-state functional connectivity (RSFC) in healthy individuals before and after PA. Right, vs. left, PA decreased RSFC in the navigation network defined by the right posterior parietal cortices (PPCs), hippocampus, and cerebellum. Right PA, relative to baseline, increased RSFC between regions within both PPCs and between the PPCs and the right middle frontal gyrus, whereas left PA decreased RSFC between these regions. These results show that right PA modulates connectivity within the right-hemisphere navigation network and shifts attention leftward by increasing connectivity in the right frontoparietal network and left PA produces essentially opposite effects, consistent with the interhemispheric competition model. These finding explain the action of PA on intact cognition and will help optimize interventions in neglect patients.

scholarly journals Saccades, attentional orienting and disengagement: the effects of anodal tDCS over right posterior parietal cortex (PPC) and frontal eye field (FEF)

2021 ◽  
Author(s):  
Lorenzo Diana ◽  
Patrick Pilastro ◽  
Edoardo N. Aiello ◽  
Aleksandra K. Eberhard-Moscicka ◽  
René M. Müri ◽  
...  
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Reaction Times ◽  
Gap Effect ◽  
Frontal Eye Field ◽  
Attentional Orienting ◽  
Eye Field ◽  
Posterior Parietal ◽  
The Right

ABSTRACTIn the present work, we applied anodal transcranial direct current stimulation (tDCS) over the posterior parietal cortex (PPC) and frontal eye field (FEF) of the right hemisphere in healthy subjects to modulate attentional orienting and disengagement in a gap-overlap task. Both stimulations led to bilateral improvements in saccadic reaction times (SRTs), with larger effects for gap trials. However, analyses showed that the gap effect was not affected by tDCS. Importantly, we observed significant effects of baseline performance that may mediate side- and task-specific effects of brain stimulation.

scholarly journals Influence of Static Magnetic Field Stimulation on the Accuracy of Tachystoscopically Presented Line Bisection

2020 ◽  
Vol 10 (12) ◽  
pp. 1006
Author(s):  
Hikari Kirimoto ◽  
Tatsunori Watanabe ◽  
Nami Kubo ◽  
Shota Date ◽  
Toru Sunagawa ◽  
...  
Keyword(s):  
Spatial Cognition ◽  
Posterior Parietal Cortex ◽  
Cortical Excitability ◽  
Superior Temporal Gyrus ◽  
Spatial Task ◽  
Leftward Bias ◽  
Sham Stimulation ◽  
Healthy Humans ◽  
Posterior Parietal ◽  
The Right

Transcranial static magnetic stimulation (tSMS) has been known to reduce human cortical excitability. Here, we investigated whether tSMS would modulate visuo-spatial cognition in healthy humans. Subjects performed a visuo-spatial task requiring judgements about the symmetry of pre-bisected lines. Visual stimuli consisted of symmetrically or asymmetrically transected lines, tachystoscopically presented for 150 ms on a computer monitor. Task performance was examined before, immediately after, and 10 min after tSMS/sham stimulation of 20 min over the posterior parietal cortex (PPC: P4 from the international 10–20 system) or superior temporal gyrus (STG: C6). Nine out of 16 subjects misjudged pre-bisected lines by consistently underestimating the length of the right-side segment (judging lines to be exactly pre-bisected when the transector was located to the left of the midpoint, or judging the left-side segment to be longer when the transector was located at the midpoint). In these subjects showing a leftward bias, tSMS over the right STG reduced the magnitude of the leftward bias. This did not occur with tSMS over the right PPC or sham stimulation. In the remaining right-biased subjects, no intervention effect was observed with any stimulation. Our findings indicate that application of tSMS over the right STG modulates visuo-spatial cognition in healthy adults.

scholarly journals Spatial attention and neglect: parietal, frontal and cingulate contributions to the mental representation and attentional targeting of salient extrapersonal events

1999 ◽  
Vol 354 (1387) ◽  
pp. 1325-1346 ◽  
Author(s):  
M.-Marsel Mesulam
Keyword(s):  
Spatial Attention ◽  
Mental Representation ◽  
Large Scale ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Attentional Focus ◽  
Posterior Parietal ◽  
Motivational Salience ◽  
The Right ◽  
Peripheral Sensory

The syndrome of contralesional neglect reflects a lateralized disruption of spatial attention. In the human, the left hemisphere shifts attention predominantly in the contralateral hemispace and in a contraversive direction whereas the right hemisphere distributes attention more evenly, in both hemispaces and both directions. As a consequence of this asymmetry, severe contralesional neglect occurs almost exclusively after right hemisphere lesions. Patients with left neglect experience a loss of salience in the mental representation and conscious perception of the left side and display a reluctance to direct orientating and exploratory behaviours to the left. Neglect is distributed according to egocentric, allocentric, world-centred, and object-centred frames of reference. Neglected events can continue to exert an implicit influence on behaviour, indicating that the attentional filtering occurs at the level of an internalized representation rather than at the level of peripheral sensory input. The unilateral neglect syndrome is caused by a dysfunction of a large-scale neurocognitive network, the cortical epicentres of which are located in posterior parietal cortex, the frontal eye fields, and the cingulate gyrus. This network coordinates all aspects of spatial attention, regardless of the modality of input or output. It helps to compile a mental representation of extrapersonal events in terms of their motivational salience, and to generate ‘kinetic strategies’ so that the attentional focus can shift from one target to another.

Modulation of Cortical Activity During Different Imitative Behaviors

2003 ◽  
Vol 89 (1) ◽  
pp. 460-471 ◽  
Author(s):  
Lisa Koski ◽  
Marco Iacoboni ◽  
Marie-Charlotte Dubeau ◽  
Roger P. Woods ◽  
John C. Mazziotta
Keyword(s):  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Mirror Neuron ◽  
Left Hand ◽  
Right Hand ◽  
Tightly Coupled ◽  
Posterior Parietal ◽  
The Right ◽  
And Control

Imitation is a basic form of motor learning during development. We have a preference to imitate the actions of others as if looking in a mirror (specular imitation: i.e., when the actor moves the left hand, the imitator moves the right hand) rather than with the anatomically congruent hand (anatomic imitation: i.e., actor and imitator both moving the right hand). We hypothesized that this preference reflects changes in activity in previously described frontoparietal cortical areas involved in directly matching observed and executed actions (mirror neuron areas). We used functional magnetic resonance imaging to study brain activity in normal volunteers imitating left and right hand movements with their right hand. Bilateral inferior frontal and right posterior parietal cortex were more active during specular imitation compared with anatomic imitation and control motor tasks. Furthermore this same pattern of activity was also observed in the rostral part of the supplementary motor area (SMA-proper) of the right hemisphere. These findings suggest that the degree of involvement of frontoparietal mirror areas in imitation depends on the nature of the imitative behavior, ruling out a linguistic mediation of these areas in imitation. Moreover, activity in the SMA appears to be tightly coupled to frontoparietal mirror areas when subjects copy the actions of others.

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