scholarly journals The Left Intraparietal Sulcus Modulates the Selection of Low Salient Stimuli

2009 ◽  
Vol 21 (2) ◽  
pp. 303-315 ◽  
Author(s):  
Carmel Mevorach ◽  
Lilach Shalev ◽  
Harriet A. Allen ◽  
Glyn W. Humphreys
Keyword(s):  
Visual Information ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Stimulus Level ◽  
Intraparietal Sulcus ◽  
Functional Lateralization ◽  
Direct Contrast ◽  
Posterior Parietal ◽  
Parietal Cortices ◽  
First Time

Neuropsychological and functional imaging studies have suggested a general right hemisphere advantage for processing global visual information and a left hemisphere advantage for processing local information. In contrast, a recent transcranial magnetic stimulation study [Mevorach, C., Humphreys, G. W., & Shalev, L. Opposite biases in salience-based selection for the left and right posterior parietal cortex. Nature Neuroscience, 9, 740–742, 2006b] demonstrated that functional lateralization of selection in the parietal cortices on the basis of the relative salience of stimuli might provide an alternative explanation for previous results. In the present study, we applied a whole-brain analysis of the functional magnetic resonance signal when participants responded to either the local or the global levels of hierarchical figures. The task (respond to local or global) was crossed with the saliency of the target level (local salient, global salient) to provide, for the first time, a direct contrast between brain activation related to the stimulus level and that related to relative saliency. We found evidence for lateralization of salience-based selection but not for selection based on the level of processing. Activation along the left intraparietal sulcus (IPS) was found when a low saliency stimulus had to be selected irrespective of its level. A control task showed that this was not simply an effect of task difficulty. The data suggest a specific role for regions along the left IPS in salience-based selection, supporting the argument that previous reports of lateralized responses to local and global stimuli were contaminated by effects of saliency.

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 A Revised Computational Neuroanatomy for Motor Control

2020 ◽  
Vol 32 (10) ◽  
pp. 1823-1836 ◽  
Author(s):  
Shlomi Haar ◽  
Opher Donchin
Keyword(s):  
Motor Control ◽  
Posterior Parietal Cortex ◽  
Motor Behavior ◽  
Premotor Cortex ◽  
Computational Neuroanatomy ◽  
Posterior Parietal ◽  
Optimal Information ◽  
Parietal Cortices ◽  
Recent Claim ◽  
New Framework

We discuss a new framework for understanding the structure of motor control. Our approach integrates existing models of motor control with the reality of hierarchical cortical processing and the parallel segregated loops that characterize cortical–subcortical connections. We also incorporate the recent claim that cortex functions via predictive representation and optimal information utilization. Our framework assumes that each cortical area engaged in motor control generates a predictive model of a different aspect of motor behavior. In maintaining these predictive models, each area interacts with a different part of the cerebellum and BG. These subcortical areas are thus engaged in domain-appropriate system identification and optimization. This refocuses the question of division of function among different cortical areas. What are the different aspects of motor behavior that are predictively modeled? We suggest that one fundamental division is between modeling of task and body whereas another is the model of state and action. Thus, we propose that the posterior parietal cortex, somatosensory cortex, premotor cortex, and motor cortex represent task state, body state, task action, and body action, respectively. In the second part of this review, we demonstrate how this division of labor can better account for many recent findings of movement encoding, especially in the premotor and posterior parietal cortices.

Reaching-related Neurons in Superior Parietal Area 5: Influence of the Target Visibility

2016 ◽  
Vol 28 (11) ◽  
pp. 1828-1837 ◽  
Author(s):  
Emiliano Brunamonti ◽  
Aldo Genovesio ◽  
Pierpaolo Pani ◽  
Roberto Caminiti ◽  
Stefano Ferraina
Keyword(s):  
Visual Information ◽  
Posterior Parietal Cortex ◽  
Hand Movement ◽  
Visual Signals ◽  
Hand Position ◽  
Movement Initiation ◽  
Starting Position ◽  
Area 5 ◽  
Posterior Parietal ◽  
Target Visibility

Reaching movements require the integration of both somatic and visual information. These signals can have different relevance, depending on whether reaches are performed toward visual or memorized targets. We tested the hypothesis that under such conditions, therefore depending on target visibility, posterior parietal neurons integrate differently somatic and visual signals. Monkeys were trained to execute both types of reaches from different hand resting positions and in total darkness. Neural activity was recorded in Area 5 (PE) and analyzed by focusing on the preparatory epoch, that is, before movement initiation. Many neurons were influenced by the initial hand position, and most of them were further modulated by the target visibility. For the same starting position, we found a prevalence of neurons with activity that differed depending on whether hand movement was performed toward memorized or visual targets. This result suggests that posterior parietal cortex integrates available signals in a flexible way based on contextual demands.

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 Human posterior parietal cortex responds to visual stimuli as early as peristriate occipital cortex

2018 ◽  
Author(s):  
Tamar I. Regev ◽  
Jonathan Winawer ◽  
Edden M. Gerber ◽  
Robert T. Knight ◽  
Leon Y. Deouell
Keyword(s):  
Visual Processing ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Intractable Epilepsy ◽  
Event Related Potentials ◽  
Visual Responses ◽  
Baseline Activity ◽  
Visual Areas ◽  
Related Potentials ◽  
Posterior Parietal

AbstractMuch of what is known about the timing of visual processing in the brain is inferred from intracranial studies in monkeys, with human data limited to mainly non-invasive methods with lower spatial resolution. Here, we estimated visual onset latencies from electrocorticographic (ECoG) recordings in a patient who was implanted with 112 sub-dural electrodes, distributed across the posterior cortex of the right hemisphere, for pre-surgical evaluation of intractable epilepsy. Functional MRI prior to surgery was used to determine boundaries of visual areas. The patient was presented with images of objects from several categories. Event Related Potentials (ERPs) were calculated across all categories excluding targets, and statistically reliable onset latencies were determined using a bootstrapping procedure over the single trial baseline activity in individual electrodes. The distribution of onset latencies broadly reflected the known hierarchy of visual areas, with the earliest cortical responses in primary visual cortex, and higher areas showing later responses. A clear exception to this pattern was robust, statistically reliable and spatially localized, very early responses on the bank of the posterior intra-parietal sulcus (IPS). The response in the IPS started nearly simultaneously with responses detected in peristriate visual areas, around 60 milliseconds post-stimulus onset. Our results support the notion of early visual processing in the posterior parietal lobe, not respecting traditional hierarchies, and give direct evidence for the upper limit of onset times of visual responses across the human cortex.

scholarly journals S140. CHARACTERISTICS OF COGNITIVE CONTROL SPECIALIZATION IN HEALTHY AND PATIENT POPULATIONS

2020 ◽  
Vol 46 (Supplement_1) ◽  
pp. S89-S89
Author(s):  
Anita Kwashie ◽  
Yizhou Ma ◽  
Andrew Poppe ◽  
Deanna Barch ◽  
Cameron Carter ◽  
...  
Keyword(s):  
Reaction Time ◽  
Cognitive Control ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Group Differences ◽  
Proactive Control ◽  
Reactive Control ◽  
Goal Maintenance ◽  
Posterior Parietal

Abstract Background Cognitive control mechanisms enable an individual to regulate, coordinate, and sequence thoughts and actions to obtain desired outcomes. A theory of control specialization posits that proactive control is necessary for anticipatory planning and goal maintenance and recruits sustained lateral prefrontal activity, whereas reactive control, essential for adapting to transient changes, marshals a more extensive brain network (Braver, 2012). Increased task errors and reduced frontoparietal activity in proactive contexts is observed in severe psychopathology, including schizophrenia (Poppe et al., 2016), leading to the prediction that patients rely on reactive control more when performing such tasks. However, evidence of primate prefrontal ‘switch’ neurons, active during both proactive and reactive contexts, challenges the notion that cognitive control relies on discrete processing networks (Blackman et al., 2016). To examine this contradiction, we sought to characterize the distinctiveness between proactive and reactive control in healthy and patient populations using the Dot Pattern Expectancy Task (DPX). We also examined if a bias toward proactive or reactive control predicted behavioral metrics. Methods 44 individuals with schizophrenia (SZ) and 50 matched healthy controls (HC) completed 4 blocks of the DPX during a 3-Tesla fMRI scan (Poppe et al., 2016). Participants followed the ‘A-then-X’ rule, in which they pressed one button whenever an A cue followed an X probe, and pressed a different button for any other non-target stimulus sequence. We examined bilateral frontoparietal ROIs from the literature for evidence of cognitive control specialization as well as whole-brain analyses. Subsequent nonparametric tests and measures of neural response variation strengthened our interpretations. Participant d’-context (dependent on task accuracy) measured their tendency to engage in proactive control. Results Behavioral data revealed that HC participants showed a greater proclivity for proactive control than did their SZ counterparts. HC reaction time outpaced SZ reaction time in trials requiring successful marshalling of proactive control. Preliminary neuroimaging analyses suggest marginal between-group differences in control specialization. HC specialization appeared to be most apparent in diffuse frontal lateral regions, and bilateral posterior parietal cortex. Within the SZ group, specialization was most evident in bilateral posterior parietal cortex. Between-group control specialization differences were most apparent in right hemisphere frontal regions. Superior frontal gyrus and medial temporal lobe activity during proactive processes accounted for modest variance in d’-context. Discussion There were significant between-group differences in goal maintenance behavioral metrics such as reaction time and a tendency to engage in proactive control. Control specialization occurred more diffusely in controls compared to patient counterparts. However, activity in these regions had minimal ability to predict behavioral metrics. Overall, the relatively small size of control-specific areas compared to regions involved in dual processing offers support for the malleable nature of regions implicated in human cognitive control.

scholarly journals From visual affordances in monkey parietal cortex to hippocampo–parietal interactions underlying rat navigation

1997 ◽  
Vol 352 (1360) ◽  
pp. 1429-1436 ◽  
Author(s):  
Michael A. Arbib
Keyword(s):  
Parietal Cortex ◽  
Visual Information ◽  
Posterior Parietal Cortex ◽  
Visual Motion ◽  
Graph Model ◽  
Brain Regions ◽  
Formal Similarity ◽  
Posterior Parietal ◽  
Level Model ◽  
Saccade Task

This paper explores the hypothesis that various subregions (but by no means all) of the posterior parietal cortex are specialized to process visual information to extract a variety of affordances for behaviour. Two biologically based models of regions of the posterior parietal cortex of the monkey are introduced. The model of the lateral intraparietal area (LIP) emphasizes its roles in dynamic remapping of the representation of targets during a double saccade task, and in combining stored, updated input with current visual input. The model of the anterior intraparietal area (AIP) addresses parietal–premotor interactions involved in grasping, and analyses the interaction between the AIP and premotor area F5. The model represents the role of other intraparietal areas working in concert with the inferotemporal cortex as well as with corollary discharge from F5 to provide and augment the affordance information in the AIP, and suggests how various constraints may resolve the action opportunities provided by multiple affordances. Finally, a systems–level model of hippocampo–parietal interactions underlying rat navigation is developed, motivated by the monkey data used in developing the above two models as well as by data on neurons in the posterior parietal cortex of the monkey that are sensitive to visual motion. The formal similarity between dynamic remapping (primate saccades) and path integration (rat navigation) is noted, and certain available data on rat posterior parietal cortex in terms of affordances for locomotion are explained. The utility of further modelling, linking the World Graph model of cognitive maps for motivated behaviour with hippocampal–parietal interactions involved in navigation, is also suggested. These models demonstrate that posterior parietal cortex is not only itself a network of interacting subsystems, but functions through cooperative computation with many other brain regions.

scholarly journals Dynamic Parieto-premotor Network for Mental Image Transformation Revealed by Simultaneous EEG and fMRI Measurement

2014 ◽  
Vol 26 (2) ◽  
pp. 232-246 ◽  
Author(s):  
Takafumi Sasaoka ◽  
Hiroaki Mizuhara ◽  
Toshio Inui
Keyword(s):  
Mental Rotation ◽  
Posterior Parietal Cortex ◽  
Premotor Cortex ◽  
Mental Image ◽  
Image Transformation ◽  
Temporal Properties ◽  
Posterior Parietal ◽  
Spatio Temporal ◽  
The Right ◽  
Parietal Cortices

Previous studies have suggested that the posterior parietal cortices and premotor areas are involved in mental image transformation. However, it remains unknown whether these regions really cooperate to realize mental image transformation. In this study, simultaneous EEG and fMRI were performed to clarify the spatio-temporal properties of neural networks engaged in mental image transformation. We adopted a modified version of the mental clock task used by Sack et al. [Sack, A. T., Camprodon, J. A., Pascual-Leone, A., & Goebel, R. The dynamics of interhemispheric compensatory processes in mental imagery. Science, 308, 702–704, 2005; Sack, A. T., Sperling, J. M., Prvulovic, D., Formisano, E., Goebel, R., Di Salle, F., et al. Tracking the mind's image in the brain II: Transcranial magnetic stimulation reveals parietal asymmetry in visuospatial imagery. Neuron, 35, 195–204, 2002]. In the modified mental clock task, participants mentally rotated clock hands from the position initially presented at a learned speed for various durations. Subsequently, they matched the position to the visually presented clock hands. During mental rotation of the clock hands, we observed significant beta EEG suppression with respect to the amount of mental rotation at the right parietal electrode. The beta EEG suppression accompanied activity in the bilateral parietal cortices and left premotor cortex, representing a dynamic cortical network for mental image transformation. These results suggest that motor signals from the premotor area were utilized for mental image transformation in the parietal areas and for updating the imagined clock hands represented in the right posterior parietal cortex.

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