Brain Commissural Anomalies

Yousefi, Behpour

doi:10.5772/33444

Cited by 4 publications

(4 citation statements)

References 191 publications

(272 reference statements)

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“…With regard to midline structures, interhemispheric commissures arise embryologically from the commissural plate of the lamina terminalis in the third month of intrauterine life, and develop in a rostrocaudal direction. Sequentially, over the course of 5 months, the rostral white commissure develops; then the hippocampal commissure, followed by the corpus callosum and, finally, the septum pellucidum . This temporal sequence suggests that agenesis of the corpus callosum is an epiphenomenon and should not be considered a specific entity, and emphasizes that anomalies during embryogenesis are time‐dependent.…”

Section: Discussionmentioning

confidence: 99%

“…Midline structures are cortico‐cortical bundles of white matter connecting the cerebral cortex of one hemisphere with the other, and include the corpus callosum, and the anterior (rostral) and hippocampal commissures. Proper regulation of sequential events of formation, cleavage, and development of these midline structures is necessary for normal development of the septum pellucidum, hippocampus and ventricular system in the mammalian brain …”

mentioning

confidence: 99%

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Characterization of an Inherited Neurologic Syndrome in Toyger Cats with Forebrain Commissural Malformations, Ventriculomegaly and Interhemispheric Cysts

Keating

Sturges

Sisó

et al. 2016

Veterinary Internal Medicne

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BackgroundIn children, frequent congenital malformations with concomitant agenesis of the corpus callosum are diagnosed by neuroimaging in association with other cerebral malformations, including interhemispheric cysts and ventriculomegaly. Similar studies providing full characterization of brain defects by in vivo magnetic resonance imaging (MRI), and correlations with the pertinent anatomic pathologic examinations are absent in veterinary medicine.Hypothesis/ObjectivesCongenital brain defects underlie the neurologic signs observed in Toyger cats selectively bred for a short ear phenotype.AnimalsUsing proper pedigree analysis and genetic evaluations, 20 related Oriental‐derived crossbred Toyger cats were evaluated. Seven clinically healthy (carrier) cats and 13 clinically affected cats that had neurologic signs, short ear phenotype and concomitant complex brain anomalies were studied.MethodsComplete physical and neurologic examinations and MRI were performed in all clinically healthy and affected cats. Postmortem and histopathologic examinations were performed in 8 affected cats and 5 healthy cats.ResultsNeurologic and MRI investigations confirmed 13 clinically affected cats with structural brain abnormalities. Ventriculomegaly with frequent concomitant supratentorial interhemispheric, communicating ventricular type‐1b cysts and multiple midline and callosal malformations were detected in all cats displaying neurologic signs. Genetic analysis confirmed autosomal recessive mode of inheritance with no chromosomal abnormalities.Conclusions and Clinical ImportanceNeuroanatomic dissections and histopathology were helpful for evaluation of abnormalities in midline brain structures, and for the full characterization of cysts. However, MRI was more sensitive for detection of small cysts. In this feline model, MRI diagnosis had extremely good correlation with pathologic abnormalities noted in the subset of animals that were examined by both modalities.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Characterization of an Inherited Neurologic Syndrome in Toyger Cats with Forebrain Commissural Malformations, Ventriculomegaly and Interhemispheric Cysts

Keating

Sturges

Sisó

et al. 2016

Veterinary Internal Medicne

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“…Crossing in the posterior part, the splenium, is completed around the 20th to 22nd week of gestation. Finally, both mature until myelination is completed around puberty (Raybaud, 2010; Yousefi, 2012 for reviews).…”

Section: Introductionmentioning

confidence: 99%

“…This connection with the occipital lobe has never been described systematically among the subjects under study (e.g., Jellison et al, 2004; Patel et al, 2010) or has been found to link both hemispheres. Nor were occipital visual cortical areas involved, identified (Yousefi, 2012 for review). Functionally, only few studies aimed at analyzing the role of the anterior commissure in transferring visual information from one hemisphere to the other.…”

Section: Introductionmentioning

confidence: 99%

Interhemispheric Connections between the Primary Visual Cortical Areas via the Anterior Commissure in Human Callosal Agenesis

Meer

Houtman

Schuerbeek

et al. 2016

Front. Syst. Neurosci.

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Aim: In humans, images in the median plane of the head either fall on both nasal hemi-retinas or on both temporal hemi-retinas. Interhemispheric connections allow cortical cells to have receptive fields on opposite sides. The major interhemispheric connection, the corpus callosum, is implicated in central stereopsis and disparity detection in front of the fixation plane. Yet individuals with agenesis of the corpus callosum may show normal stereopsis and disparity vergence. We set out to study a possible interhemispheric connection between primary visual cortical areas via the anterior commissure to explain this inconsistency because of the major role of these cortical areas in elaborating 3D visual perception.Methods: MRI, DTI and tractography of the brain of a 53-year old man with complete callosal agenesis and normal binocular single vision was undertaken. Tractography seed points were placed in both the right and the left V1 and V2. Nine individuals with both an intact corpus callosum and normal binocularity served as controls.Results: Interhemispheric tracts through the anterior commissure linking both V1 and V2 visual cortical areas bilaterally were indeed shown in the subject with callosal agenesis. All other individuals showed interhemispheric visual connections through the corpus callosum only.Conclusion: Callosal agenesis may result in anomalous interhemispheric connections of the primary visual areas via the anterior commissure. It is proposed here that these connections form as alternative to the normal callosal pathway and may participate in binocularity.

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