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Daniel Ansari - One of the best experts on this subject based on the ideXlab platform.

  • Developmental specialization of the left Intraparietal Sulcus for symbolic ordinal processing.
    Cortex; a journal devoted to the study of the nervous system and behavior, 2018
    Co-Authors: Anna A. Matejko, Jane E. Hutchison, Daniel Ansari
    Abstract:

    Abstract Symbolic numbers have both cardinal (symbol-quantity) and ordinal (symbol–symbol) referents. Despite behavioural evidence suggesting distinct processing of cardinal and ordinal referents, little consensus has emerged from the neuroimaging literature on whether these processes have shared or distinct neural underpinnings. Moreover, it remains unclear how the neural correlates of cardinal and ordinal processing change with age. To address these unresolved questions, we investigated the neural correlates of cardinal (neural distance effect) and ordinal processing (neural reverse distance effect) in 50 children (ages 7–10) and 26 adults (ages 19–26). We found that adults recruited a largely left lateralized set of fronto-parietal regions for ordinal processing, whereas children showed activation in the right lateral orbital and inferior frontal gyri for both ordinal and cardinal processing. Additional analyses suggested that adults recruited the left Intraparietal Sulcus (IPS) more than children for ordinal processing, suggesting that the IPS may become increasingly tuned to ordinal symbolic properties over development. Together with previous literature documenting the importance of the left IPS for cardinal processing, our results suggest that cardinal and ordinal processing may share neural substrates in the left IPS and that this region may become specialized for both skills over development.

  • The left Intraparietal Sulcus adapts to symbolic number in both the visual and auditory modalities: Evidence from fMRI.
    NeuroImage, 2017
    Co-Authors: Stephan E. Vogel, Celia Goffin, Joshua Bohnenberger, Karl Koschutnig, Gernot Reishofer, Roland H. Grabner, Daniel Ansari
    Abstract:

    Abstract A growing body of evidence from functional Magnetic Resonance Imaging adaptation (fMRIa) has implicated the left Intraparietal Sulcus (IPS) as a crucial brain region representing the semantic of number symbols. However, it is currently unknown to what extent the left IPS brain activity can be generalized across modalities (e.g., Arabic digits and spoken number words) and how robust and reproducible numerical adaptation effects are. In two separate fMRIa experiments we habituated the brain response of 20 native English-speaking (Experiment 1) and 34 native German-speaking (Experiment 2) adults to Arabic digits or spoken number words. Consistent with previous findings, experiment 1 revealed numerical ratio dependent adaptation to Arabic numerals in the left IPS using both conventional and cortex-based alignment techniques. Experiment 2 revealed numerical ratio dependent signal recovery in the left IPS following adaptation to both Arabic numerals and spoken number words using both conventional and cortex-based alignment techniques. Together, these findings suggest that the left IPS is involved in symbolic number processing across modalities.

  • The role of the left Intraparietal Sulcus in the relationship between symbolic number processing and children's arithmetic competence.
    Developmental cognitive neuroscience, 2012
    Co-Authors: Stephanie Bugden, Gavin R. Price, D. Adam Mclean, Daniel Ansari
    Abstract:

    The neural foundations of arithmetic learning are not well understood. While behavioral studies have revealed relationships between symbolic number processing and individual differences in children's arithmetic performance, the neurocognitive mechanisms that bind symbolic number processing and arithmetic are unknown. The current fMRI study investigated the relationship between children's brain activation during symbolic number comparison (Arabic digits) and individual differences in arithmetic fluency. A significant correlation was found between the numerical ratio effect on reaction times and accuracy and children's arithmetic scores. Furthermore, children with a stronger neural ratio effect in the left Intraparietal Sulcus (IPS) during symbolic number processing exhibited higher arithmetic scores. Previous research has demonstrated that activation of the IPS during numerical magnitude processing increases over the course of development, and that the left IPS plays an important role in symbolic number processing. The present findings extend this knowledge to show that children with more mature response modulation of the IPS during symbolic number processing exhibit higher arithmetic competence. These results suggest that the left IPS is a key neural substrate for the relationship between the relative of precision of the representation of numerical magnitude and school-level arithmetic competence.

  • Developmental specialization in the right Intraparietal Sulcus for the abstract representation of numerical magnitude
    Journal of cognitive neuroscience, 2010
    Co-Authors: Ian D. Holloway, Daniel Ansari
    Abstract:

    Because number is an abstract quality of a set, the way in which a number is externally represented does not change its quantitative meaning. In this study, we examined the development of the brain regions that support format-independent representation of numerical magnitude. We asked children and adults to perform both symbolic (Hindu-Arabic numerals) and nonsymbolic (arrays of squares) numerical comparison tasks as well as two control tasks while their brains were scanned using fMRI. In a preliminary analysis, we calculated the conjunction between symbolic and nonsymbolic numerical comparison. We then examined in which brain regions this conjunction differed between children and adults. This analysis revealed a large network of visual and parietal regions that showed greater activation in adults relative to children. In our primary analysis, we examined age-related differences in the conjunction of symbolic and nonsymbolic comparison after subtracting the control tasks. This analysis revealed a much more limited set of regions including the right inferior parietal lobe near the Intraparietal Sulcus. In addition to showing increased activation to both symbolic and nonsymbolic magnitudes over and above activation related to response selection, this region showed age-related differences in the distance effect. Our findings demonstrate that the format-independent representation of numerical magnitude in the right inferior parietal lobe is the product of developmental processes of cortical specialization and highlight the importance of using appropriate control tasks when conducting developmental neuroimaging studies.

  • Age-related Changes in the Activation of the Intraparietal Sulcus during Nonsymbolic Magnitude Processing: An Event-related Functional Magnetic Resonance Imaging Study
    Journal of cognitive neuroscience, 2006
    Co-Authors: Daniel Ansari, Bibek Dhital
    Abstract:

    Numerical magnitude processing is an essential everyday skill. Functional brain imaging studies with human adults have repeatedly revealed that bilateral regions of the Intraparietal Sulcus are correlated with various numerical and mathematical skills. Surprisingly little, however, is known about the development of these brain representations. In the present study, we used functional neuroimaging to compare the neural correlates of nonsymbolic magnitude judgments between children and adults. Although behavioral performance was similar across groups, in comparison to the group of children the adult participants exhibited greater effects of numerical distance on the left Intraparietal Sulcus. Our findings are the first to reveal that even the most basic aspects of numerical cognition are subject to age-related changes in functional neuroanatomy. We propose that developmental impairments of number may be associated with atypical specialization of cortical regions underlying magnitude processing.

Peter Janssen - One of the best experts on this subject based on the ideXlab platform.

  • Caudal Intraparietal Sulcus and three-dimensional vision: A combined functional magnetic resonance imaging and single-cell study.
    NeuroImage, 2017
    Co-Authors: Amir-mohammad Alizadeh, Ilse Van Dromme, Bram-ernst Verhoef, Peter Janssen
    Abstract:

    The cortical network processing three-dimensional (3D) object structure defined by binocular disparity spans both the ventral and dorsal visual streams. However, very little is known about the neural representation of 3D structure at intermediate levels of the visual hierarchy. Here, we investigated the neural selectivity for 3D surfaces in the macaque Posterior Intraparietal area (PIP) in the medial bank of the caudal Intraparietal Sulcus (IPS). We first identified a region sensitive to depth-structure information in the medial bank of the caudal IPS using functional Magnetic Resonance Imaging (fMRI), and then recorded single-cell activity within this fMRI activation in the same animals. Most PIP neurons were selective for the 3D orientation of planar surfaces (first-order disparity) at very short latencies, whereas a very small fraction of PIP neurons were selective for curved surfaces (second-order disparity). A linear support vector machine classifier could reliably identify the direction of the disparity gradient in planar and curved surfaces based on the responses of a population of disparity-selective PIP neurons. These results provide the first detailed account of the neuronal properties in area PIP, which occupies an intermediate position in the hierarchy of visual areas involved in processing depth structure from disparity.

  • The relation between functional magnetic resonance imaging activations and single-cell selectivity in the macaque Intraparietal Sulcus
    NeuroImage, 2015
    Co-Authors: Ilse Van Dromme, Wim Vanduffel, Peter Janssen
    Abstract:

    Previous functional magnetic resonance (fMRI) studies in humans and monkeys have demonstrated that the anterior Intraparietal Sulcus (IPS) is sensitive to the depth structure defined by binocular disparity. However, in the macaque monkey, a single large activation was measured in the anterior lateral bank of the IPS, whereas in human subjects two separate regions were sensitive to depth structure from disparity. We performed fMRI and single-cell experiments in the same animals, in a large number of recording sites in the lateral bank of the IPS. The fMRI interaction effect between the factors curvature (curved or flat) and disparity (stereo or control) correctly predicted the location of higher-order disparity selective neurons that encoded the depth structure of objects. However the large region in the IPS activated by depth structure consisted of two patches of higher-order disparity-selective neurons, one in the anterior IPS and one located more posteriorly, surrounded by regions lacking such selectivity. Thus the IPS region activated by curved surfaces consists of at least two patches of higher-order disparity selective neurons, which may reconcile previous fMRI studies in monkeys and humans.

  • effective connectivity of depth structure selective patches in the lateral bank of the macaque Intraparietal Sulcus
    PLOS Biology, 2015
    Co-Authors: Elsie Premereur, Ilse Van Dromme, Wim Vanduffel, Maria C Romero, Peter Janssen
    Abstract:

    Extrastriate cortical areas are frequently composed of subpopulations of neurons encoding specific features or stimuli, such as color, disparity, or faces, and patches of neurons encoding similar stimulus properties are typically embedded in interconnected networks, such as the attention or face-processing network. The goal of the current study was to examine the effective connectivity of subsectors of neurons in the same cortical area with highly similar neuronal response properties. We first recorded single- and multi-unit activity to identify two neuronal patches in the anterior part of the macaque Intraparietal Sulcus (IPS) showing the same depth structure selectivity and then employed electrical microstimulation during functional magnetic resonance imaging in these patches to determine the effective connectivity of these patches. The two IPS subsectors we identified—with the same neuronal response properties and in some cases separated by only 3 mm—were effectively connected to remarkably distinct cortical networks in both dorsal and ventral stream in three macaques. Conversely, the differences in effective connectivity could account for the known visual-to-motor gradient within the anterior IPS. These results clarify the role of the anterior IPS as a pivotal brain region where dorsal and ventral visual stream interact during object analysis. Thus, in addition to the anatomical connectivity of cortical areas and the properties of individual neurons in these areas, the effective connectivity provides novel key insights into the widespread functional networks that support behavior.

  • Effective Connectivity of Depth-Structure–Selective Patches in the Lateral Bank of the Macaque Intraparietal Sulcus
    PLoS biology, 2015
    Co-Authors: Elsie Premereur, Ilse Van Dromme, Wim Vanduffel, Maria C Romero, Peter Janssen
    Abstract:

    Extrastriate cortical areas are frequently composed of subpopulations of neurons encoding specific features or stimuli, such as color, disparity, or faces, and patches of neurons encoding similar stimulus properties are typically embedded in interconnected networks, such as the attention or face-processing network. The goal of the current study was to examine the effective connectivity of subsectors of neurons in the same cortical area with highly similar neuronal response properties. We first recorded single- and multi-unit activity to identify two neuronal patches in the anterior part of the macaque Intraparietal Sulcus (IPS) showing the same depth structure selectivity and then employed electrical microstimulation during functional magnetic resonance imaging in these patches to determine the effective connectivity of these patches. The two IPS subsectors we identified—with the same neuronal response properties and in some cases separated by only 3 mm—were effectively connected to remarkably distinct cortical networks in both dorsal and ventral stream in three macaques. Conversely, the differences in effective connectivity could account for the known visual-to-motor gradient within the anterior IPS. These results clarify the role of the anterior IPS as a pivotal brain region where dorsal and ventral visual stream interact during object analysis. Thus, in addition to the anatomical connectivity of cortical areas and the properties of individual neurons in these areas, the effective connectivity provides novel key insights into the widespread functional networks that support behavior.

Naoyuki Osaka - One of the best experts on this subject based on the ideXlab platform.

  • Differential contributions of the Intraparietal Sulcus and the inferior parietal lobe to attentional blink: Evidence from transcranial magnetic stimulation
    Journal of cognitive neuroscience, 2011
    Co-Authors: Ken Kihara, Nobuyuki Hirose, Tatsuya Mima, Hidenao Fukuyama, Takashi Ikeda, Daisuke Matsuyoshi, Naoyuki Osaka
    Abstract:

    When two targets (T1 and T2) are to be identified in rapid serial visual presentation, the response to T1 induces impairment of T2 report if T2 appears within 500 msec after T1 (attentional blink: AB). AB is thought to reflect temporal limitations of attention which affect target perception. Recent research suggests that the Intraparietal Sulcus (IPS) contributes to an attentional set associated with task goals, whereas the inferior parietal lobe (IPL) is associated with the disengagement and reorienting of attention to a relevant stimulus presented outside the current focus of attention. We investigated respective involvement of the IPS and the IPL in AB using transcranial magnetic stimulation (TMS). The results of Experiment 1 showed that the magnitude of AB deficit decreased TMS disrupted activity of the IPS after T1 onset. In addition, an increased AB deficit occurred when TMS was delivered over the IPS or IPL after T2 onset. In Experiment 2, where participants were instructed to ignore T1, they showed an AB-like T2 deficit only when TMS was delivered to the IPS after a T2 onset. Findings are discussed in terms of hypotheses about the respective roles of the IPS, in realizing an attentional set, and the IPL, in contributing to a disengagement of attention (from T1 to T2) during an AB period.

  • The role of left and right Intraparietal Sulcus in the attentional blink: A transcranial magnetic stimulation study
    Experimental brain research, 2007
    Co-Authors: Ken Kihara, Nobuyuki Hirose, Tatsuya Mima, Mitsunari Abe, Hidenao Fukuyama, Naoyuki Osaka
    Abstract:

    Processing of one visual target (T1) makes it difficult to become aware of a second target (T2), when two targets, embedded in a stream of distractor stimuli, occur within about 500 ms. This phenomenon is known as attentional blink (AB) and reflects the temporal limitation in allocating visual attention. Although several studies suggest that parietal regions are concerned with the AB phenomenon, their functional relevance remains unclear. We investigated whether left and/or right Intraparietal Sulcus (IPS) contributed to the AB bottleneck using transcranial magnetic stimulation (TMS). The course of recovery from the AB deficit was facilitated when single pulse TMS induced a transient interruption of left or right IPS activity at a T1-TMS stimulus onset asynchrony of 350 ms, while there was no effect of TMS or sham stimulation delivered over Cz with the same timing. These results provide direct evidence that activation of left as well as right IPS is involved in the genesis of AB. This finding supports the idea that the IPS plays a critical role in the cortical network controlling the temporal dynamics of visual awareness.

Roberto Dell'acqua - One of the best experts on this subject based on the ideXlab platform.

  • Functional dissociation of anterior cingulate cortex and Intraparietal Sulcus in visual working memory.
    Cortex; a journal devoted to the study of the nervous system and behavior, 2019
    Co-Authors: Gian Marco Duma, Giovanni Mento, Simone Cutini, Paola Sessa, Sylvain Baillet, Sabrina Brigadoi, Roberto Dell'acqua
    Abstract:

    Abstract Previous electrophysiological studies of lateralized visual working memory (VWM) identified an ERP component, defined as contralateral delay activity (CDA), directly modulated by the number of items held in memory. One of the main candidate as the cortical source of this ERP component is the inferior Intraparietal Sulcus (IPS). Moreover, previous neuroimaging studies put forth evidence for the presence of a distributed VWM network involving also prefrontal areas and in particular the anterior cingulate cortex (ACC). Nonetheless, the understanding of the functional role of ACC is still debated. We recorded the high-density EEG in 20 healthy participants undergoing a VWM and a control task. Explorative cluster-based permutation statistics confirmed the posterior memory load dependent CDA modulation, but also identified an additional anterior cluster of electrodes whose amplitude was modulated by memory load. The source reconstruction revealed a memory load dependent activation in the IPS but also in the ACC, suggesting that these two areas might be nodes of a fronto-parietal circuit underlying VWM maintenance. Crucially, parietal and prefrontal areas showed a temporal dissociation, since IPS was more engaged in the early phase of visual information storage while the ACC was more active during the late phase. This pattern suggests a functional dissociation between the parietal cortex, which is involved in encoding and storage of information, and prefrontal areas, subserving cognitive control processes, including the boosting and protection of information from decay. Remarkably, the connection strength between IPS and ACC predicted the individual number of items held in memory. These findings are discussed within the theoretical account of a neural distributed model of VWM.

  • On the role of the inferior Intraparietal Sulcus in visual working memory for lateralized single-feature objects
    Journal of cognitive neuroscience, 2016
    Co-Authors: Sabrina Brigadoi, Simone Cutini, Paola Sessa, Federica Meconi, Marco Castellaro, Mattia Marangon, Alessandra Bertoldo, Pierre Jolicœur, Roberto Dell'acqua
    Abstract:

    A consolidated practice in cognitive neuroscience is to explore the properties of human visual working memory through the analysis of electromagnetic signals using cued change detection tasks. Under these conditions, EEG/MEG activity increments in the posterior parietal cortex scaling with the number of memoranda are often reported in the hemisphere contralateral to the objects' position in the memory array. This highly replicable finding clashes with several reported failures to observe compatible hemodynamic activity modulations using fMRI or fNIRS in comparable tasks. Here, we reconcile this apparent discrepancy by acquiring fMRI data on healthy participants and employing a cluster analysis to group voxels in the posterior parietal cortex based on their functional response. The analysis identified two distinct subpopulations of voxels in the Intraparietal Sulcus IPS showing a consistent functional response among participants. One subpopulation, located in the superior IPS, showed a bilateral response to the number of objects coded in visual working memory. A different subpopulation, located in the inferior IPS, showed an increased unilateral response when the objects were displayed contralaterally. The results suggest that a cluster of neurons in the inferior IPS is a candidate source of electromagnetic contralateral responses to working memory load in cued change detection tasks.

Scott T Grafton - One of the best experts on this subject based on the ideXlab platform.

  • Differential Recruitment of Anterior Intraparietal Sulcus and Superior Parietal Lobule during Visually Guided Grasping Revealed by Electrical Neuroimaging
    The Journal of neuroscience : the official journal of the Society for Neuroscience, 2008
    Co-Authors: Eugene Tunik, Stephanie Ortigue, Serge V. Adamovich, Scott T Grafton
    Abstract:

    Dorsal parietal cortex is required for visually guided prehension. Transcranial magnetic stimulation to either the anterior Intraparietal Sulcus (aIPS) or superior parietal lobule (SPL) disrupts on-line adaptive adjustments of grasp when objects are perturbed. We used high-density electroencephalography during grasping to determine the relative timing of these two areas and to test whether the temporal contribution of each site would change when the task goal was perturbed. During object grasping with the right-hand, two distinct evoked responses were present over the 50-100 and 100-200 ms periods after movement onset. Distributed linear source estimation of these scalp potentials localized left lateralized sources, first in the aIPS and then the SPL. The duration of the response from the aIPS area was longer when there was an object perturbation. Initiation of a corrective movement coincided with activation in SPL. These data support a two-stage process: the integration of target goal and an emerging action plan within aIPS and subsequent on-line adjustments within SPL.

  • Beyond grasping: representation of action in human anterior Intraparietal Sulcus.
    Neuroimage, 2007
    Co-Authors: Scott T Grafton
    Abstract:

    The fronto-parietal network has been implicated in the processing of multisensory information for motor control. Recent methodological advances with both fMRI and TMS provide the opportunity to dissect the functionality of this extensive network in humans and may identify distinct contributions of local neural populations within this circuit that are not only related to motor planning, but to goal oriented behavior as a whole. Herein, we review and make parallels between experiments in monkeys and humans on a broad array of motor as well as non-motor tasks in order to characterize the specific contribution of a region in the parietal lobe, the anterior Intraparietal Sulcus (aIPS). The intent of this article is to review: (1) the historical perspectives on the parietal lobe, particularly the aIPS; (2) extend and update these perspectives based on recent empirical data; and (3) discuss the potential implications of the revised functionality of the aIPS in relationship to complex goal oriented behavior and social interaction. Our contention is that aIPS is a critical node within a network involved in the higher order dynamic control of action, including representation of intended action goals. These findings may be important not only for guiding the design of future experiments investigating related issues but may also have valuable utility in other fields, such social neuroscience and biomedical engineering.

  • The anterior Intraparietal Sulcus mediates grasp execution, independent of requirement to update: new insights from transcranial magnetic stimulation.
    The Journal of neuroscience : the official journal of the Society for Neuroscience, 2006
    Co-Authors: Nichola J. Rice, Eugene Tunik, Scott T Grafton
    Abstract:

    Although a role of the Intraparietal Sulcus (IPS) in grasping is becoming evident, the specific contribution of regions within the IPS remains undefined. In this vein, transcranial magnetic stimulation (TMS) was delivered to the anterior (aIPS), middle (mIPS), and caudal (cIPS) IPS in two tasks designed to dissociate the potential roles of the IPS in either grasp planning or execution (task 1) and its involvement in error detection or error correction (task 2). Determining the involvement of specific regions of the IPS in perceptual (planning and error detection) versus motor (execution and correction) components of grasping allowed us to assess the ecological validity of competing computational models attempting to simulate reach-to-grasp movements. In task 1, we demonstrate that, when no on-line adjustment is necessary, TMS to aIPS (but not mIPS or cIPS) disrupts grasping; this disruption is only elicited when TMS is applied during the execution (but not the planning) phase of the movement. Task 2 reveals that TMS to aIPS (but not mIPS or cIPS) disrupts grasping in the presence of a perturbation; this disruption is only elicited when TMS is applied during the error correction (but not error detection) phase of the movement. We propose that the specific contribution of the aIPS in grasping is in the on-line computation of a difference vector based on motor goal, efference copy, and sensory inputs. This computation is performed for both stable and perturbed motor goals.

  • Goal representation in human anterior Intraparietal Sulcus.
    J Neurosci, 2006
    Co-Authors: Scott T Grafton
    Abstract:

    When a child reaches toward a cookie, the watching parent knows immediately what the child wants. The neural basis of this ability to interpret other people's actions in terms of their goals has been the subject of much speculation. Research with infants has shown that 6 month olds respond when they see an adult reach to a novel goal but habituate when an adult reaches to the same goal repeatedly. We used a similar approach in an event-related functional magnetic resonance imaging experiment. Adult participants observed a series of movies depicting goal-directed actions, with the sequence controlled so that some goals were novel and others repeated relative to the previous movie. Repeated presentation of the same goal caused a suppression of the blood oxygen level-dependent response in two regions of the left Intraparietal Sulcus. These regions were not sensitive to the trajectory taken by the actor's hand. This result demonstrates that the anterior Intraparietal Sulcus represents the goal of an observed action.