Interhemispheric connections between primary visual areas: beyond the midline rule

Houzel, Jean-Christophe; Carvalho, Maria Luiza; Lent, Roberto

doi:10.1590/s0100-879x2002001200005

Cited by 36 publications

(37 citation statements)

References 57 publications

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“…In humans, it consists of ϳ200 million axons, making it the largest fiber tract within the CNS (Funnell et al, 2000;Houzel et al, 2002). It integrates information from the right and left hemispheres, and enables numerous complex brain activities (Mihrshahi, 2006).…”

Section: Discussionmentioning

confidence: 99%

Segregation and Pathfinding of Callosal Axons through EphA3 Signaling

Nishikimi¹,

Oishi²,

Tabata³

et al. 2011

J. Neurosci.

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The corpus callosum, composed of callosal axons, is the largest structure among commissural connections in eutherian animals. Axon pathfinding of callosal neurons has been shown to be guided by intermediate targets, such as midline glial structures. However, it has not yet been understood completely how axon-axon interactions, another major mechanism for axon pathfinding, are involved in the pathfinding of callosal neurons. Here, we show that callosal axons from the medial and lateral regions of the mouse cerebral cortex pass through the dorsal and ventral parts, respectively, of the corpus callosum. Using an explant culture system, we observed that the axons from the medial and lateral cortices were segregated from each other in vitro, and that this segregation was attenuated by inhibition of EphA3 signaling. We also found that knockdown of EphA3, which is preferentially expressed in the lateral cortex, resulted in disorganized segregation of the callosal axons and disrupted axon pathfinding in vivo. These results together suggest the role of axonal segregation in the corpus callosum, mediated at least in part by EphA3, in correct pathfinding of callosal neurons.

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Section: Discussionmentioning

confidence: 99%

Segregation and Pathfinding of Callosal Axons through EphA3 Signaling

Nishikimi¹,

Oishi²,

Tabata³

et al. 2011

J. Neurosci.

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“…It has been shown that hemispheric interaction is critical for a unified representation of world (Houzel et al 2002), coordinating movement (Gerloff and Andres 2002), attentional processing (Banich 1998), pooling processing resources (Liederman 1998), and parallel processing (Compton 2002) among others. Bilaterally synchronous BOLD fluctuations have been previously observed in the motor cortex (Cordes et al 2000), visual cortex, thalamus, and hippocampus of humans (Stein et al 2000) and in the oculomotor and somatomotor areas of monkeys (Vincent et al 2007).…”

Section: Connectivity Patternsmentioning

confidence: 99%

Functional Networks in the Anesthetized Rat Brain Revealed by Independent Component Analysis of Resting-State fMRI

Hutchison

Mirsattari

Jones

et al. 2010

Journal of Neurophysiology

149

143

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Hutchison RM, Mirsattari SM, Jones CK, Gati JS, Leung LS. Functional networks in the anesthetized rat brain revealed by independent component analysis of resting-state fMRI. J Neurophysiol 103: 3398-3406, 2010. First published April 21, 2010 doi:10.1152/jn.00141.2010. The rodent brain is organized into functional networks that can be studied through examination of synchronized low-frequency spontaneous fluctuations (LFFs) of the functional magnetic resonance imaging -blood-oxygen-level-dependent (BOLD) signal. In this study, resting networks of LFFs were estimated from the whole-brain BOLD signals using independent component analysis (ICA). ICA provides a hypothesis-free technique for determining the functional connectivity map that does not require a priori selection of a seed region. Twenty Long-Evans rats were anesthetized with isoflurane (1%, n ϭ 10) or ketamine/xylazine (50/6 mg · kg Ϫ1 · h Ϫ1 ip, n ϭ 10) and imaged for 5-10 min in a 9.4 T MR scanner without experimental stimulation or task requirement. Independent, synchronous LFFs of BOLD signals were found to exist in clustered, bilaterally symmetric regions of both cortical and subcortical structures, including primary and secondary somatosensory cortices, motor cortices, visual cortices, posterior and anterior cingulate cortices, hippocampi, caudate-putamen, and thalamic and hypothalamic nuclei. The somatosensory and motor cortices typically demonstrated both symmetric and asymmetric components with unique frequency profiles. Similar independent network components were found under isoflurane and ketamine/xylazine anesthesia. The report demonstrates, for the first time, 12 independent resting networks that are bilaterally synchronous in different cortical and subcortical areas of the rat brain.

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“…It is possible that the corpus callosum is involved in more subtle mechanisms of depth perception than stereopsis (which is specifically defined as binocular disparity), such as relative motion or parallax, that is, using the differences in relative motion of near and far objects to judge depth (31). In this context, it has been suggested that visual callosal fibers participate in predicting trajectories of moving objects across the midline, and in the generation of binding mechanisms in the central visual field (19,20).…”

Section: Visual Callosal Fibers: Midline Fusion and Depth Perceptionmentioning

confidence: 99%

“…Furthermore, analyses of the morphology and diameter of callosal axonal branches suggest that the architecture of callosal axons is suitable to promote the synchronous activation of multiple targets in the opposite hemisphere (16). It would not be surprising that processes such as depth perception or binding in the central visual field depend on the generation of synchronous ensembles of neuronal activity in the two hemispheres, for which callosal fibers may be fundamental (20).…”

Section: Factors Favoring the Expansion Of The Corpus Callosum: Intermentioning

confidence: 99%

One hundred million years of interhemispheric communication: the history of the corpus callosum

Aboitiz

Montiel

2003

Braz J Med Biol Res

335

223

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Analysis of regional corpus callosum fiber composition reveals that callosal regions connecting primary and secondary sensory areas tend to have higher proportions of coarse-diameter, highly myelinated fibers than callosal regions connecting so-called higher-order areas. This suggests that in primary/secondary sensory areas there are strong timing constraints for interhemispheric communication, which may be related to the process of midline fusion of the two sensory hemifields across the hemispheres. We postulate that the evolutionary origin of the corpus callosum in placental mammals is related to the mechanism of midline fusion in the sensory cortices, which only in mammals receive a topographically organized representation of the sensory surfaces. The early corpus callosum may have also served as a substrate for growth of fibers connecting higher-order areas, which possibly participated in the propagation of neuronal ensembles of synchronized activity between the hemispheres. However, as brains became much larger, the increasingly longer interhemispheric distance may have worked as a constraint for efficient callosal transmission. Callosal fiber composition tends to be quite uniform across species with different brain sizes, suggesting that the delay in callosal transmission is longer in bigger brains. There is only a small subset of large-diameter callosal fibers whose size increases with increasing interhemispheric distance. These limitations in interhemispheric connectivity may have favored the development of brain lateralization in some species like humans.

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Interhemispheric connections between primary visual areas: beyond the midline rule

Cited by 36 publications

References 57 publications

Segregation and Pathfinding of Callosal Axons through EphA3 Signaling

Segregation and Pathfinding of Callosal Axons through EphA3 Signaling

Functional Networks in the Anesthetized Rat Brain Revealed by Independent Component Analysis of Resting-State fMRI

One hundred million years of interhemispheric communication: the history of the corpus callosum

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