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Ranzini M, Ferrazzi G, D'Imperio D, Giustiniani A, Danesin L, D'Antonio V, Rigon E, Cacciante L, Rigon J, Meneghello F, Turolla A, Vallesi A, Semenza C, Burgio F. White matter tract disconnection in Gerstmann's syndrome: Insights from a single case study. Cortex 2023; 166:322-337. [PMID: 37478549 DOI: 10.1016/j.cortex.2023.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 02/17/2023] [Accepted: 05/18/2023] [Indexed: 07/23/2023]
Abstract
It has been suggested that Gerstmann's syndrome is the result of subcortical disconnection rather than emerging from damage of a multifunctional brain region within the parietal lobe. However, patterns of white matter tract disconnection following parietal damage have been barely investigated. This single case study allows characterising Gerstmann's syndrome in terms of disconnected networks. We report the case of a left parietal patient affected by Gerstmann's tetrad: agraphia, acalculia, left/right orientation problems, and finger agnosia. Lesion mapping, atlas-based estimation of probability of disconnection, and DTI-based tractography revealed that the lesion was mainly located in the superior parietal lobule, and it caused disruption of both intraparietal tracts passing through the inferior parietal lobule (e.g., tracts connecting the angular, supramarginal, postcentral gyri, and the superior parietal lobule) and fronto-parietal long tracts (e.g., the superior longitudinal fasciculus). The lesion site appears to be located more superiorly as compared to the cerebral regions shown active by other studies during tasks impaired in the syndrome, and it reached the subcortical area potentially critical in the emergence of the syndrome, as hypothesised in previous studies. Importantly, the reconstruction of tracts connecting regions within the parietal lobe indicates that this critical subcortical area is mainly crossed by white matter tracts connecting the angular gyrus and the superior parietal lobule. Taken together, these findings suggest that this case study might be considered as empirical evidence of Gerstmann's tetrad caused by disconnection of intraparietal white matter tracts.
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Affiliation(s)
| | | | | | | | | | | | - Elena Rigon
- IRCCS San Camillo Hospital, Lido of Venice, Italy
| | | | - Jessica Rigon
- UOC Cure Primarie - Distretto 3, Mirano - Dolo, AULSS 3, Serenissima, Italy
| | | | - Andrea Turolla
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Antonino Vallesi
- Department of Neuroscience (DNS), University of Padova, Italy; Padova Neuroscience Center, University of Padova, Italy
| | - Carlo Semenza
- Department of Neuroscience (DNS), University of Padova, Italy; Padova Neuroscience Center, University of Padova, Italy
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Barton JJ, Rubino C, Albonico A, Jackson M, Davies-Thompson J. Right hemi-alexia. Cortex 2022; 157:288-303. [PMID: 36370599 DOI: 10.1016/j.cortex.2022.09.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 09/02/2022] [Accepted: 09/26/2022] [Indexed: 12/15/2022]
Abstract
While pure alexia was long considered a disconnection syndrome, it may also be a selective visual word agnosia due to damage to the visual word form area. Disconnection is still the likely explanation of hemi-alexias, though, particularly when splenial lesions damage inter-hemispheric projections and cause left hemi-alexia. An intra-hemispheric disconnection causing right hemi-alexia is theoretically possible but seems very rare, with only a single report that has been challenged on the grounds of inadequate perimetry. We describe the case of PH, who had a severe reading deficit in her right hemifield. Detailed perimetry showed only a small relative hemi-scotoma along the horizontal meridian, while word reading was impaired over a much larger expanse of her right hemifield, in which object recognition was spared. Reading, lexical decisions, and perceptual discrimination of words were impaired in the right hemifield, and this extended to letters and numbers, with a trend to an effect on the perception of an unfamiliar script, namely Korean. On magnetic resonance imaging she had a large left lateral occipital meningioma with vasogenic edema of occipital white matter tracts. Functional magnetic resonance imaging showed that the visual word form area was located just anterior to the mass. Her perceptual abnormalities resolved after resection of the tumor. We conclude that right hemi-alexia exists and is most likely due to intra-hemispheric disconnection of occipital input to the visual word form area.
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Affiliation(s)
- Jason Js Barton
- Departments of Medicine (Neurology), Ophthalmology and Visual Science, University of British Columbia, Vancouver, Canada; Departments of Ophthalmology and Visual Science, University of British Columbia, Vancouver, Canada.
| | - Cristina Rubino
- Graduate Program in Rehabilitative Sciences, University of British Columbia, Vancouver, Canada.
| | - Andrea Albonico
- Departments of Medicine (Neurology), Ophthalmology and Visual Science, University of British Columbia, Vancouver, Canada; Departments of Ophthalmology and Visual Science, University of British Columbia, Vancouver, Canada.
| | - MaryLou Jackson
- Departments of Ophthalmology and Visual Science, University of British Columbia, Vancouver, Canada.
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Bullock DN, Hayday EA, Grier MD, Tang W, Pestilli F, Heilbronner SR. A taxonomy of the brain's white matter: twenty-one major tracts for the 21st century. Cereb Cortex 2022; 32:4524-4548. [PMID: 35169827 PMCID: PMC9574243 DOI: 10.1093/cercor/bhab500] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 01/26/2023] Open
Abstract
The functional and computational properties of brain areas are determined, in large part, by their connectivity profiles. Advances in neuroimaging and network neuroscience allow us to characterize the human brain noninvasively, but a comprehensive understanding of the human brain demands an account of the anatomy of brain connections. Long-range anatomical connections are instantiated by white matter, which itself is organized into tracts. These tracts are often disrupted by central nervous system disorders, and they can be targeted by neuromodulatory interventions, such as deep brain stimulation. Here, we characterized the connections, morphology, traversal, and functions of the major white matter tracts in the brain. There are major discrepancies across different accounts of white matter tract anatomy, hindering our attempts to accurately map the connectivity of the human brain. However, we are often able to clarify the source(s) of these discrepancies through careful consideration of both histological tract-tracing and diffusion-weighted tractography studies. In combination, the advantages and disadvantages of each method permit novel insights into brain connectivity. Ultimately, our synthesis provides an essential reference for neuroscientists and clinicians interested in brain connectivity and anatomy, allowing for the study of the association of white matter's properties with behavior, development, and disorders.
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Affiliation(s)
- Daniel N Bullock
- Department of Psychological and Brain Sciences, Program in Neuroscience, Indiana University Bloomington, Bloomington, IN 47405, USA,Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Elena A Hayday
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mark D Grier
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | | | | | - Sarah R Heilbronner
- Address correspondence to Sarah R. Heilbronner, Department of Neuroscience, University of Minnesota, 2-164 Jackson Hall, 321 Church St SE, Minneapolis, MN 55455, USA.
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Herbet G, Duffau H. Revisiting the Functional Anatomy of the Human Brain: Toward a Meta-Networking Theory of Cerebral Functions. Physiol Rev 2020; 100:1181-1228. [PMID: 32078778 DOI: 10.1152/physrev.00033.2019] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
For more than one century, brain processing was mainly thought in a localizationist framework, in which one given function was underpinned by a discrete, isolated cortical area, and with a similar cerebral organization across individuals. However, advances in brain mapping techniques in humans have provided new insights into the organizational principles of anatomo-functional architecture. Here, we review recent findings gained from neuroimaging, electrophysiological, as well as lesion studies. Based on these recent data on brain connectome, we challenge the traditional, outdated localizationist view and propose an alternative meta-networking theory. This model holds that complex cognitions and behaviors arise from the spatiotemporal integration of distributed but relatively specialized networks underlying conation and cognition (e.g., language, spatial cognition). Dynamic interactions between such circuits result in a perpetual succession of new equilibrium states, opening the door to considerable interindividual behavioral variability and to neuroplastic phenomena. Indeed, a meta-networking organization underlies the uniquely human propensity to learn complex abilities, and also explains how postlesional reshaping can lead to some degrees of functional compensation in brain-damaged patients. We discuss the major implications of this approach in fundamental neurosciences as well as for clinical developments, especially in neurology, psychiatry, neurorehabilitation, and restorative neurosurgery.
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Affiliation(s)
- Guillaume Herbet
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France; Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors," INSERM U1191, Institute of Functional Genomics, Montpellier, France; and University of Montpellier, Montpellier, France
| | - Hugues Duffau
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France; Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors," INSERM U1191, Institute of Functional Genomics, Montpellier, France; and University of Montpellier, Montpellier, France
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Herbet G, Zemmoura I, Duffau H. Functional Anatomy of the Inferior Longitudinal Fasciculus: From Historical Reports to Current Hypotheses. Front Neuroanat 2018; 12:77. [PMID: 30283306 PMCID: PMC6156142 DOI: 10.3389/fnana.2018.00077] [Citation(s) in RCA: 192] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 08/30/2018] [Indexed: 12/13/2022] Open
Abstract
The inferior longitudinal fasciculus (ILF) is a long-range, associative white matter pathway that connects the occipital and temporal-occipital areas of the brain to the anterior temporal areas. In view of the ILF's anatomic connections, it has been suggested that this pathway has a major role in a relatively large array of brain functions. Until recently, however, the literature data on these potential functions were scarce. Here, we review the key findings of recent anatomic, neuromodulation, and neuropsychological studies. We also summarize reports on how this tract is disrupted in a wide range of brain disorders, including psychopathologic, neurodevelopmental, and neurologic diseases. Our review reveals that the ILF is a multilayered, bidirectional tract involved in processing and modulating visual cues and thus in visually guided decisions and behaviors. Accordingly, sudden disruption of the ILF by neurologic insult is mainly associated with neuropsychological impairments of visual cognition (e.g., visual agnosia, prosopagnosia, and alexia). Furthermore, disruption of the ILF may constitute the pathophysiologic basis for visual hallucinations and socio-emotional impairments in schizophrenia, as well as emotional difficulties in autism spectrum disorder. Degeneration of the ILF in neurodegenerative diseases affecting the temporal lobe may explain (at least in part) the gradual onset of semantic and lexical access difficulties. Although some of the functions mediated by the ILF appear to be relatively lateralized, observations from neurosurgery suggest that disruption of the tract's anterior portion can be dynamically compensated for by the contralateral portion. This might explain why bilateral disruption of the ILF in either acute or progressive disease is highly detrimental in neuropsychological terms.
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Affiliation(s)
- Guillaume Herbet
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France
- INSERM-1051, Team 4, Saint-Eloi Hospital, Institute for Neurosciences of Montpellier, Montpellier, France
- University of Montpellier, Montpellier, France
| | - Ilyess Zemmoura
- Department of Neurosurgery, Tours University Medical Center, Tours, France
- UMR 1253, iBrain, INSERM, University of Tours, Tours, France
| | - Hugues Duffau
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France
- INSERM-1051, Team 4, Saint-Eloi Hospital, Institute for Neurosciences of Montpellier, Montpellier, France
- University of Montpellier, Montpellier, France
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