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 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 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 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.

Motor Subcircuits Mediating the Control of Movement Velocity: A PET Study

1998 ◽  
Vol 80 (4) ◽  
pp. 2162-2176 ◽  
Author(s):  
Robert S. Turner ◽  
Scott T. Grafton ◽  
John R. Votaw ◽  
Mahlon R. Delong ◽  
John M. Hoffman
Keyword(s):  
Motor Control ◽  
Basal Ganglia ◽  
Right Hemisphere ◽  
Movement Velocity ◽  
Rate Effects ◽  
Regression Slopes ◽  
The Right ◽  
Parietal Cortices ◽  
Linear Contrasts ◽  
Rate Of Movement

Turner, Robert S., Scott T. Grafton, John R. Votaw, Mahlon R. DeLong, and John M. Hoffman. Motor subcircuits mediating the control of movement velocity: a PET study. J. Neurophysiol. 80: 2162–2176, 1998. The influence of changes in the mean velocity of movement on regional cerebral blood flow (rCBF) was studied using positron emission tomography (PET) in nine healthy right-handed adults while they performed a smooth pursuit visuomanual tracking task. Images of relative rCBF were obtained while subjects moved a hand-held joystick to track the movement of a target at three different rates of a sinusoidal displacement (0.1, 0.4, and 0.7 Hz). Significant changes in rCBF between task conditions were detected using analysis of variance and weighted linear contrasts. The kinematics of arm and eye movements indicated that subjects performed tasks in a similar manner, particularly during the faster two tracking conditions. Significant increases in rCBF during arm movement (relative to an eye tracking only control condition) were detected in a widespread network of areas known for their involvement in motor control. The activated areas included primary sensorimotor (M1S1), dorsal and mesial premotor, and dorsal parietal cortices in the left hemisphere and to a lesser extent the sensorimotor and superior parietal cortices in the right hemisphere. Subcortically, activations were found in the left putamen, globus pallidus (GP), and thalamus, in the right basal ganglia, and in the right anterior cerebellum. Within the cerebral volume activated with movement, three areas had changes in rCBF that correlated positively with the rate of movement: left M1S1, left GP, and right anterior cerebellum. No movement-related sites had rCBF that correlated negatively with the rate of movement. Regressions of mean percent change (MPC) in rCBF onto mean hand velocity yielded two nonoverlapping subpopulations of movement-related loci, the three sites with significant rate effects and regression slopes steeper than 0.17 MPC⋅cm−1⋅s−1 and all other sites with nonsignificant rate effects and regression slopes below 0.1 MPC⋅cm−1⋅s−1. Moreover, the effects of movement per se and of movement velocity varied in magnitude independently. These results confirm previous reports that movement-related activations of M1S1 and cerebellum are sensitive to movement frequency or some covarying parameter of movement. The activation of GP with increasing movement velocity, not described in previous functional-imaging studies, supports the hypothesis that the basal ganglia motor circuit may be involved preferentially in controlling or monitoring the scale and/or dynamics of arm movements. The remaining areas that were activated equally for all movement rates may be involved in controlling higher level aspects of motor control that are independent of movement dynamics.

scholarly journals Parental Education, Ethnicity, and Functional Connectivity between Nucleus Accumbens and Frontoparietal Network

2021 ◽  
Author(s):  
Shervin Assari
Keyword(s):  
Nucleus Accumbens ◽  
Functional Connectivity ◽  
Resting State ◽  
Parental Education ◽  
Black People ◽  
Right Hemisphere ◽  
Latino Youth ◽  
Resting State Functional Connectivity ◽  
Cross Sectional ◽  
Frontoparietal Network

While studies have indicated an association between socioeconomic status (SES) and neuroimaging measures, weaker SES effects are shown for Blacks than Whites. This is, in part, due to processes such as stratification, racism, minoritization, and othering of Black people in the United States. However, less is known about Latino youth. This study had two aims: First, to test the association between parental education and the right and left nucleus accumbens (NAcc) resting-state functional connectivity with the frontoparietal network (FPN) in children; and second, to investigate ethnic heterogeneity in this association. This cross-sectional study used data from the Adolescent Brain Cognitive Development (ABCD) study. We analyzed the resting-state functional connectivity data (rsFC) of 10,840 US preadolescents who were between 9 and 10 years old. The main outcomes were the NAcc resting-state functional connectivity with FPN separately calculated for right and left hemispheres. Parental education was our independent variable. Family structure, sex, and age were covariates. Furthermore, ethnicity (Latino vs. non-Latino) was regarded as the moderator. We used mixed-effects regression for data analysis with and without interaction terms between parental education and ethnicity. Most participants (n = 8690; 80.2%) were non-Latino and 2150 (19.8%) were Latino. Parental education was associated with higher right and left NAcc resting-state functional connectivity with FPN. Ethnicity showed statistically significant interactions with parental education, suggesting that the positive associations between parental education and right and left NAcc resting-state functional connectivity with FPN were different in non-Latino and Latino children. For right hemisphere, we found significantly stronger and for left hemisphere, we found significantly weaker association for Latino compared with non-Latino preadolescents. Preadolescents’ NAcc resting-state functional connectivity with FPN depends on the intersections of ethnicity, parental education, and laterality.

scholarly journals Virtual reality-based sensorimotor adaptation shapes subsequent spontaneous and naturalistic stimulus-driven brain activity

2021 ◽  
Author(s):  
Meytal Wilf ◽  
Celine Dupuis ◽  
Davide Nardo ◽  
Diana Huber ◽  
Sibilla Sander ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Large Scale ◽  
Right Hemisphere ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Visual Response ◽  
Spatial Shift ◽  
Before And After ◽  
Behavioural Tests ◽  
The Right

Our everyday life summons numerous novel sensorimotor experiences, to which our brain needs to adapt in order to function properly. However, tracking plasticity of naturalistic behaviour and associated brain modulations is challenging. Here we tackled this question implementing a prism adaptation training in virtual reality (VRPA) in combination with functional neuroimaging. Three groups of healthy participants (N=45) underwent VRPA (with a spatial shift either to the left/right side, or with no shift), and performed fMRI sessions before and after training. To capture modulations in free-flowing, task-free brain activity, the fMRI sessions included resting state and free viewing of naturalistic videos. We found significant decreases in spontaneous functional connectivity between large-scale cortical networks, namely attentional and default mode/fronto-parietal networks, only for adaptation groups. Additionally, VRPA was found to bias visual representations of naturalistic videos, as following rightward adaptation, we found upregulation of visual response in an area in the parieto-occipital sulcus (POS) in the right hemisphere. Notably, the extent of POS upregulation correlated with the size of the VRPA induced after-effect measured in behavioural tests. This study demonstrates that a brief VRPA exposure is able to change large-scale cortical connectivity and correspondingly bias the representation of naturalistic sensory inputs.

scholarly journals Age dependency and lateralization in the three branches of the human superior longitudinal fasciculus

2021 ◽  
Author(s):  
Kaoru Amemiya ◽  
Eiichi Naito ◽  
Hiromasa Takemura
Keyword(s):  
Right Hemisphere ◽  
Age Groups ◽  
White Matter Tract ◽  
Age Dependency ◽  
Diffusion Weighted Mri ◽  
Superior Longitudinal Fasciculus ◽  
Wide Range ◽  
Adolescents And Adults ◽  
The Right ◽  
Parietal Cortices

AbstractThe superior longitudinal fascicle/fasciculus (SLF) is a major white matter tract connecting the frontal and parietal cortices in humans. Although the SLF has often been analyzed as a single entity, several studies have reported that the SLF is segregated into three distinct branches (SLF I, II, and III). They have also reported the right lateralization of the SLF III volume and discussed its relationship with lateralized cortical functions in the fronto-parietal network. However, to date, the homogeneity or heterogeneity of the age dependency and lateralization properties of SLF branches have not been fully clarified. Through this study, we aimed to clarify the age dependency and lateralization of SLF I-III by analyzing diffusion-weighted MRI (dMRI) and quantitative R1 (qR1) map datasets collected from a wide range of age groups, mostly comprising right-handed children, adolescents, adults, and seniors (6 to 81 years old). The age dependency in dMRI measurement (fractional anisotropy, FA) was heterogeneous among the three SLF branches, suggesting that these branches are regulated by distinct developmental and aging processes. Lateralization analysis on SLF branches revealed that the right SLF III was larger than the left SLF III in adults, replicating previous reports. FA measurement also suggested that, in addition to SLF III, SLF II was lateralized to the right hemisphere in adolescents and adults. We further found a left lateralization of SLF I in qR1 data, a microstructural measurement sensitive to myelin levels, in adults. These findings suggest that the SLF sub-bundles are distinct entities in terms of age dependency and lateralization.

scholarly journals Immersive virtual prism adaptation therapy with depth sensing camera: A feasibility study with functional near infrared spectroscopy in healthy adults

2021 ◽  
Author(s):  
Sungmin Cho ◽  
Won-Seok Kim ◽  
Jihong Park ◽  
Seung Hyun Lee ◽  
Jongseung Lee ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Right Hemisphere ◽  
Prism Adaptation ◽  
Spatial Neglect ◽  
Depth Sensing ◽  
Functional Near Infrared Spectroscopy ◽  
Unilateral Spatial Neglect ◽  
The Right

Unilateral spatial neglect (USN) is common after stroke and associated with poor functional recovery. Prism adaptation (PA) is one of the most supported modality able to ameliorate USN but underapplied due to several issues. Using immersive virtual reality and depth-sensing camera, we developed the virtual prism adaptation therapy (VPAT) to overcome the limitations in conventional PA. In this study, we investigated whether VPAT can induce behavioral adaptations and which cortical area is most significantly activated. Fourteen healthy subjects participated in this study. The experiment consisted of four sequential phases (pre-VAPT, VPAT-10°, VPAT-20°, and post-VPAT) with functional near-infrared spectroscopy recordings. Each phase consisted of alternating target pointing and resting (or clicking) blocks. To find out the most significantly activated area during pointing in different phases (VPAT-10°, VPAT-20°, and Post-VPAT) in contrast to pointing during the pre-VPAT phase, we analyzed changes in oxyhemoglobin concentration during pointing. The pointing errors of the virtual hand deviated to the right-side during early pointing blocks in the VPAT-10°and VPAT-20°phases. There was a left-side deviation of the real hand to the target in the post-VPAT phase. The most significantly activated channels were all located in the right hemisphere, and possible corresponding cortical areas included the dorsolateral prefrontal cortex and frontal eye field. In conclusion, VPAT may induce behavioral adaptation with modulation of the dorsal attentional network. Future clinical trials using multiple sessions of a high degree of rightward deviation VPAT over a more extended period are required in stroke patients with unilateral spatial neglect.

scholarly journals Prism adaptation speeds reach initiation in the direction of the prism after-effect.

2021 ◽  
Author(s):  
Christopher Lee Striemer ◽  
Carley Borza
Keyword(s):  
Sensory Input ◽  
Right Hemisphere ◽  
Prism Adaptation ◽  
Spatial Neglect ◽  
Egocentric Reference Frame ◽  
After Effect ◽  
The Right ◽  
Reach Planning ◽  
Direction Opposite ◽  
Healthy Participants

Damage to the temporal-parietal cortex in the right hemisphere often leads to spatial neglect – a disorder in which patients are unable to attend to sensory input from their contralesional (left) side. Neglect has been associated with both attentional and premotor deficits. That is, in addition to having difficulty with attending to the left side, patients are often slower to initiate leftward vs. rightward movements (i.e., directional hypokinesia). Previous research has indicated that a brief period of adaptation to rightward shifting prisms can reduce symptoms of neglect by adjusting the patient’s movements leftward, towards the neglected field. Although prism adaptation has been shown to reduce spatial attention deficits in patients with neglect, very little work has examined the effects of prisms on premotor symptoms. In the current study, we examined this in healthy individuals using leftward shifting prisms to induce a rightward shift in the egocentric reference frame, similar to neglect patients prior to prism adaptation. Specifically, we examined the speed with which healthy participants initiated leftward and rightward reaches (without visual feedback) prior to and following adaptation to either 17° leftward (n=16) or 17° rightward (n=15) shifting prisms. Our results indicated that, following adaptation, participants were significantly faster to initiate reaches towards targets located in the direction opposite the prism shift. That is, participants were faster to initiate reaches to right targets following leftward prism adaptation, and were faster to initiate reaches to left targets following rightward prism adaptation. Overall these results are consistent with the idea that prism adaptation can influence the speed with which a reach can be planned toward a target in the direction opposite the prism shift, possibly through altering activity in neural circuits involved in reach planning.

scholarly journals Modulation of Working Memory and Resting-State fMRI by tDCS of the Right Frontoparietal Network

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Monika Pupíková ◽  
Patrik Šimko ◽  
Martin Gajdoš ◽  
Irena Rektorová
Keyword(s):  
Working Memory ◽  
Resting State ◽  
Large Scale ◽  
Memory Task ◽  
Resting State Fmri ◽  
Resting State Functional Connectivity ◽  
Double Blind ◽  
Frontoparietal Network ◽  
Cognitive Speed ◽  
The Right

Many cognitive functions, including working memory, are processed within large-scale brain networks. We targeted the right frontoparietal network (FPN) with one session of transcranial direct current stimulation (tDCS) in an attempt to modulate the cognitive speed of a visual working memory task (WMT) in 27 young healthy subjects using a double-blind crossover design. We further explored the neural underpinnings of induced changes by performing resting-state fMRI prior to and immediately after each stimulation session with the main focus on the interaction between a task-positive FPN and a task-negative default mode network (DMN). Twenty minutes of 2 mA anodal tDCS was superior to sham stimulation in terms of cognitive speed manipulation of a subtask with processing of objects and tools in unconventional views (i.e., the higher cognitive load subtask of the offline WMT). This result was linked to the magnitude of resting-state functional connectivity decreases between the stimulated FPN seed and DMN seeds. We provide the first evidence for the action reappraisal mechanism of object and tool processing. Modulation of cognitive speed of the task by tDCS was reflected by FPN-DMN cross-talk changes.

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