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Jakub Limanowski, Felix Blankenburg
Spatially and temporally congruent visuotactile stimulation of a fake hand together with one's real hand may result in an illusory self-attribution of the fake hand. Although this illusion relies on a representation of the two touched body parts in external space, there is tentative evidence that, for the illusion to occur, the seen and felt touches also need to be congruent in an anatomical reference frame. We used functional magnetic resonance imaging and a somatotopical, virtual reality-based setup to isolate the neuronal basis of such a comparison...
2018: Frontiers in Human Neuroscience
Xiaodong Chen, Gregory C DeAngelis, Dora E Angelaki
By systematically manipulating head position relative to the body and eye position relative to the head, previous studies have shown that vestibular tuning curves of neurons in the ventral intraparietal (VIP) area remain invariant when expressed in body-/world-centered coordinates. However, body orientation relative to the world was not manipulated; thus, an egocentric, body-centered representation could not be distinguished from an allocentric, world-centered reference frame. We manipulated the orientation of the body relative to the world such that we could distinguish whether vestibular heading signals in VIP are organized in body- or world-centered reference frames...
March 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
Valerio Santangelo
Higher-order cognitive processes were shown to rely on the interplay between large-scale neural networks. However, brain networks involved with the capability to split attentional resource over multiple spatial locations and multiple stimuli or sensory modalities have been largely unexplored to date. Here I re-analyzed data from Santangelo et al. (2010) to explore the causal interactions between large-scale brain networks during divided attention. During fMRI scanning, participants monitored streams of visual and/or auditory stimuli in one or two spatial locations for detection of occasional targets...
2018: Frontiers in Integrative Neuroscience
Tim Rohe, Uta Noppeney
Behaviorally, it is well established that human observers integrate signals near-optimally weighted in proportion to their reliabilities as predicted by maximum likelihood estimation. Yet, despite abundant behavioral evidence, it is unclear how the human brain accomplishes this feat. In a spatial ventriloquist paradigm, participants were presented with auditory, visual, and audiovisual signals and reported the location of the auditory or the visual signal. Combining psychophysics, multivariate functional MRI (fMRI) decoding, and models of maximum likelihood estimation (MLE), we characterized the computational operations underlying audiovisual integration at distinct cortical levels...
January 2018: ENeuro
Giacomo Rizzolatti, Stefano Rozzi
The mirror mechanism is a basic mechanism that transforms sensory representations of others' actions into motor representations of the same actions in the brain of the observer. The mirror mechanism plays an important role in understanding actions of others. In the present chapter we discuss first the basic organization of the posterior parietal lobe in the monkey, stressing that it is best characterized as a motor scaffold, on the top of which sensory information is organized. We then describe the location of the mirror mechanism in the posterior parietal cortex of the monkey, and its functional role in areas PFG, and anterior, ventral, and lateral intraparietal areas...
2018: Handbook of Clinical Neurology
Svenja Caspers, Karl Zilles
This chapter summarizes current knowledge on the structural segregation of the parietal lobe based on cyto-, myelo-, and receptorarchitectonic studies, as well as the connectivity of this brain region with other cortical and subcortical structures. The anterior part of the human parietal cortex comprises the somatosensory areas 3a, 3b, 1, and 2, whereas the posterior part contains seven multimodal areas in both the superior and inferior parietal lobules. Available cytoarchitectonic maps of the human intraparietal sulcus do not provide a complete picture yet...
2018: Handbook of Clinical Neurology
Elena Rusconi
This chapter offers a perspective on the origin, operational definition, historic vicissitudes, and current status of Gerstmann syndrome. The main issues and controversy accompanying Gerstmann syndrome throughout the years are reviewed. The clinical picture of Gerstmann syndrome as it emerges from a series of modern-day pure cases is described. In current clinical practice, a diagnosis of Gerstmann syndrome indicates the concomitant presence of four acquired symptoms: finger agnosia, acalculia, left-right disorientation, and agraphia...
2018: Handbook of Clinical Neurology
Ruey-Song Huang, Martin I Sereno
The parietal lobe plays a major role in sensorimotor integration and action. Recent neuroimaging studies have revealed more than 40 retinotopic areas distributed across five visual streams in the human brain, two of which enter the parietal lobe. A series of retinotopic areas occupy the length of the intraparietal sulcus and continue into the postcentral sulcus. On the medial wall, retinotopy extends across the parieto-occipital sulcus into the precuneus and reaches the cingulate sulcus. Full-body tactile stimulation revealed a multisensory homunculus lying along the postcentral sulcus just posterior to primary somatosensory cortical areas and overlapping with the anteriormost retinotopic maps...
2018: Handbook of Clinical Neurology
Johannes Bloechle, Julia F Huber, Elise Klein, Julia Bahnmueller, Johannes Rennig, Korbinian Moeller, Stefan Huber
Performance in visual quantification tasks shows two characteristic patterns as a function of set size. A precise subitizing process for small sets (up to four) was contrasted with an approximate estimation process for larger sets. The spatial arrangement of elements in a set also influences visual quantification performance, with frequently perceived arrangements (e.g., dice patterns) being faster enumerated than random arrangements. Neuropsychological and imaging studies identified the intraparietal sulcus (IPS), as key brain area for quantification, both within and above the subitizing range...
2018: Frontiers in Human Neuroscience
Thomas B Christophel, Polina Iamshchinina, Chang Yan, Carsten Allefeld, John-Dylan Haynes
Items held in working memory can be either attended or not, depending on their current behavioral relevance. It has been suggested that unattended contents might be solely retained in an activity-silent form. Instead, we demonstrate here that encoding unattended contents involves a division of labor. While visual cortex only maintains attended items, intraparietal areas and the frontal eye fields represent both attended and unattended items.
March 5, 2018: Nature Neuroscience
Barbara Tomasino, Maria Nobile, Marta Re, Monica Bellina, Marco Garzitto, Filippo Arrigoni, Massimo Molteni, Franco Fabbro, Paolo Brambilla
This fMRI study investigated mental simulation of state/psychological and action verbs during adolescence. Sixteen healthy subjects silently read verbs describing a motor scene or not (STIMULUS: motor, state/psychological verbs) and they were explicitly asked to imagine the situation or they performed letter detection preventing them from using simulation (TASK: imagery vs. letter detection). A significant task by stimuli interaction showed that imagery of state/psychological verbs, as compared to action stimuli (controlled by the letter detection) selectively increased activation in the right supramarginal gyrus/rolandic operculum and in the right insula, and decreased activation in the right intraparietal sulcus...
March 2, 2018: Brain and Cognition
Hongkeun Kim
Functional neuroimaging studies on episodic memory retrieval consistently indicated the activation of the precuneus (PCU), mid-cingulate cortex (MCC), and lateral intraparietal sulcus (latIPS) regions. Although studies typically interpreted these activations in terms of memory retrieval processes, resting-state functional connectivity data indicate that these regions are part of the frontoparietal control network, suggesting a more general, cross-functional role. In this regard, this study proposes a novel hypothesis which suggests that the parietal control network plays a strong role in accommodating the co-occurrence of externally directed cognition (EDC) and internally directed cognition (IDC), which are typically antagonistic to each other...
March 15, 2018: Brain Research
Mulugeta Semework, Sara C Steenrod, Michael E Goldberg
Humans effortlessly establish a gist-like memory of their environment whenever they enter a new place, a memory that can guide action even in the absence of vision. Neurons in the lateral intraparietal area (LIP) of the monkey exhibit a form of this environmental memory. These neurons respond when a monkey makes a saccade that brings the spatial location of a stimulus that appeared on a number of prior trials, but not on the present trial, into their receptive fields (RFs). The stimulus need never have appeared in the neuron's RF...
February 16, 2018: ELife
Minye Zhan, Rainer Goebel, Beatrice de Gelder
Visual perception includes ventral and dorsal stream processes. However, it is still unclear whether the former is predominantly related to conscious and the latter to nonconscious visual perception as argued in the literature. In this study upright and inverted body postures were rendered either visible or invisible under continuous flash suppression (CFS), while brain activity of human participants was measured with functional MRI (fMRI). Activity in the ventral body-sensitive areas was higher during visible conditions...
January 2018: ENeuro
Kristin N Meyer, Feng Du, Emily Parks, Joseph B Hopfinger
Despite behavioral and electrophysiological evidence for dissociations between endogenous (voluntary) and exogenous (reflexive) attention, fMRI results have yet to consistently and clearly differentiate neural activation patterns between these two types of attention. This study specifically aimed to determine whether activity in the dorsal fronto-parietal network differed between endogenous and exogenous conditions. Participants performed a visual discrimination task in endogenous and exogenous attention conditions while undergoing fMRI scanning...
February 6, 2018: Neuropsychologia
Sophia Bakola, Lauretta Passarelli, Tony Huynh, Daniele Impieri, Katrina H Worthy, Patrizia Fattori, Claudio Galletti, Kathleen J Burman, Marcello G P Rosa
The parietal reach region (PRR) in the medial bank of the macaque intraparietal sulcus has been a subject of considerable interest in research aimed at the development of brain-controlled prosthetic arms, but its anatomical organization remains poorly characterized. We examined the anatomical organization of the putative PRR territory based on myeloarchitecture and retrograde tracer injections. We found that the medial bank includes three areas: an extension of the dorsal subdivision of V6A (V6Ad), the medial intraparietal area (MIP), and a subdivision of area PE (PEip)...
November 2017: ENeuro
Mojtaba Soltanlou, Christina Artemenko, Ann-Christine Ehlis, Stefan Huber, Andreas J Fallgatter, Thomas Dresler, Hans-Christoph Nuerk
Neurocognitive studies of arithmetic learning in adults have revealed decreasing brain activation in the fronto-parietal network, along with increasing activation of specific cortical and subcortical areas during learning. Both changes are associated with a shift from procedural to retrieval strategies for problem-solving. Here we address the critical, open question of whether similar neurocognitive changes are also evident in children. In this study, 20 typically developing children were trained to solve simple and complex multiplication problems...
January 26, 2018: Scientific Reports
Jonathan A Michaels, Hansjörg Scherberger
Preparing and executing grasping movements demands the coordination of sensory information across multiple scales. The position of an object, required hand shape, and which of our hands to extend must all be coordinated in parallel. The network formed by the macaque anterior intraparietal area (AIP) and hand area (F5) of the ventral premotor cortex is essential in the generation of grasping movements. Yet, the role of this circuit in hand selection is unclear. We recorded from 1342 single- and multi-units in AIP and F5 of two macaque monkeys (Macaca mulatta) during a delayed grasping task in which monkeys were instructed by a visual cue to perform power or precision grips on a handle presented in five different orientations with either the left or right hand, as instructed by an auditory tone...
January 26, 2018: Scientific Reports
Valeria C Caruso, Daniel S Pages, Marc A Sommer, Jennifer M Groh
We accurately perceive the visual scene despite moving our eyes ~3 times per second, an ability that requires incorporation of eye position and retinal information. In this study, we assessed how this neural computation unfolds across three interconnected structures: frontal eye fields (FEF), intraparietal cortex (LIP/MIP), and the superior colliculus (SC). Single unit activity was assessed in head-restrained monkeys performing visually-guided saccades from different initial fixations. As previously shown, the receptive fields of most LIP/MIP neurons shifted to novel positions on the retina for each eye position, and these locations were not clearly related to each other in either eye- or head-centered coordinates (defined as hybrid coordinates)...
December 20, 2017: Journal of Neurophysiology
Elisabeth M Robin, Pascaline B Pey, Pauline de Fornel-Thibaud, Pierre H M Moissonnier, Valérie Freiche
CASE DESCRIPTION A 10-year-old spayed female Rottweiler was referred for evaluation because of a 2-month history of regurgitation and weight loss, despite no apparent change in appetite. The dog had received antiemetic and antacid treatment, without improvement. CLINICAL FINDINGS Physical examination revealed a low body condition score (2/5), but other findings were unremarkable. Diffuse, global esophageal dilatation was noted on plain thoracic radiographs, and normal motility was confirmed through videofluoroscopic evaluation of swallowing...
February 1, 2018: Journal of the American Veterinary Medical Association
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