Callosal connections correlate preferentially with ipsilateral cortical domains in cat areas 17 and 18, and with contralateral domains in the 17/18 transition zone

Olavarría, Jaime F.

doi:10.1002/cne.1152

Cited by 49 publications

(69 citation statements)

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“…Studying the formation of callosal maps will also provide insight on the role the eyes play in the development of other cortical visual maps. The findings are not likely to be speciesspecific because retinotopically matched callosal linkages exist in widely different species (Pritzel et al, 1988;Lewis and Olavarria, 1995;Olavarria 1996Olavarria ,2001aBosking et al, 2000).…”

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confidence: 82%

“…Olavarria and colleagues proposed that the temporal retina, through a system of bilateral projections, promotes the formation of callosal linkages primarily between opposite cortical loci that are retinotopically matched (i.e., they represent the same retinal locus). Under this topographical constraint, callosal fibers connect loci that are nonmirror-symmetric with respect to the brain midline (Lewis and Olavarria, 1995;Olavarria, 1996Olavarria, , 2001a. In contrast, in the absence of retinal input callosal fibers connect opposite cortical loci that are largely mirrorsymmetric with respect to the midline (Olavarria and Li, 1995).…”

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confidence: 88%

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Retinal influences specify cortico‐cortical maps by postnatal day six in rats and mice

Olavarría

Hiroi

2003

J of Comparative Neurology

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Studies of callosal projections in striate cortex show that the retina is involved in the development of topographical connections. In normal animals callosal fibers connect retinotopically corresponding, nonmirror-symmetric cortical loci, whereas in animals bilaterally enucleated at birth, callosal fibers connect topographically mismatched, mirror-symmetric loci. Moreover, in rodents the overall pattern of visual callosal connections is adult-like by postnatal day 12 (P12). In this study we delayed the onset of retinal deafferentation in rats and mice in order to determine the period when retinal influences are critically needed for the development of retinotopically matched callosal linkages. Callosal maps were revealed by placing small injections of retrogradely and anterogradely transported tracers into different loci of lateral striate cortex. We found that the patterns of callosal linkages in rats enucleated at P12, P8, and P6 were nonmirror-symmetric, as in normally reared rats. In contrast, the patterns of linkages in rats enucleated at P4 closely resembled the mirror-symmetric pattern seen in rats enucleated at birth (P0). A similar reversal in topography (from symmetric to nonsymmetric) occurred in mice when enucleation was delayed from P4 to P6. These findings indicate that retinal input prior to P6, but not prior to P4, is sufficient for specifying normal callosal topography. Moreover, they suggest that development of retinotopically matched callosal linkages depends critically on retinal influences during a brief period between P4 and P6, when callosal connections are still very immature.

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confidence: 82%

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confidence: 88%

Retinal influences specify cortico‐cortical maps by postnatal day six in rats and mice

Olavarría

Hiroi

2003

J of Comparative Neurology

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“…3E). Orientation columns at the representations of the VM in both hemispheres receive similar afferent input and also mutual input mediated by callosal connections concentrated in the vicinity of the VM representation (44,45). By the mismatch Δ LR , we quantified the absolute value of differences between left and right maps averaged over a strip of 3 mm width adjacent to the V1/V2 border.…”

Section: Components Of Column Spacing Variabilitymentioning

confidence: 99%

Interareal coordination of columnar architectures during visual cortical development

Kaschube

Schnabel

Wolf

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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The formation of cortical columns is often conceptualized as a local process in which synaptic microcircuits confined to the volume of the emerging column are established and selectively refined. Many neurons, however, while wiring up locally are simultaneously building macroscopic circuits spanning widely distributed brain regions, such as different cortical areas or the two brain hemispheres. Thus, it is conceivable that interareal interactions shape the local column layout. Here we show that the columnar architectures of different areas of the cat visual cortex in fact develop in a coordinated manner, not adequately described as a local process. This is revealed by comparing the layouts of orientation columns (i) in left/right pairs of brain hemispheres and (ii) in areas V1 and V2 of individual brain hemispheres. Whereas the size of columns varied strongly within all areas considered, columns in different areas were typically closely matched in size if they were mutually connected. During development, we find that such mutually connected columns progressively become better matched in size as the late phase of the critical period unfolds. Our results suggest that one function of critical-period plasticity is to progressively coordinate the functional architectures of different cortical areas-even across hemispheres.cerebral cortex | critical period | postnatal development | visual cortex | orientation columns A general principle of cerebral cortical organization states that the neocortex is subdivided into numerous functionally and anatomically distinct areas (1, 2). In evolution, the subdivision into distinct areas arose concurrently with the invention of the neocortex in the first mammals (3), and the multiplication of functional areas appears as the central process that increases neocortical functionality in later mammalian evolution (3,4). In all mammalian brains, multiple functional areas are interconnected within a brain hemisphere, and also across hemispheres, by a dense network of intrahemispheric and callosal interareal connections (2, 5, 6). These connections constitute a large fraction of the cerebral white matter and are likely to physically shape cortical morphology during the growth of the brain (7). Although many cortical areas appear specialized for particular-information processing steps, most functions of cortical processing involve the activation of distributed processing networks that span many anatomically distinct areas. The interactions among these areas are structured such that even the most simple sensory stimuli activate large groups of neurons distributed over multiple areas in a coordinated and temporally overlapping manner (5,(8)(9)(10).Over the past two decades, the important role of distributed nerve-cell networks for sensory perception or the planning and execution of movements utilizing behavioral contextual information has been increasingly taken into account (8, 10-13). In contrast, the role of interareal networks for the developmental specification of the functional processi...

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“…This system has unique topographic as well as plasticity features that make it ideal for investigating the development of cortical maps. We have previously proposed that the temporal retina, through a system of bilateral projections, promotes the formation of callosal linkages between opposite cortical loci in lateral striate cortex that are both retinotopically matched (i.e., they represent the same retinal locus), and nonmirrorsymmetric with respect to the brain midline (Lewis and Olavarria, 1995;Olavarria, 1996Olavarria, , 2001a. Because of the nonsymmetry of callosal linkages in lateral striate cortex, intracortical tracer injections separated by a few hundred microns typically produce distinctly different projection patterns, a property that can facilitate the detection of topographic maps in very young animals.…”

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Development of callosal topography in visual cortex of normal and enucleated rats

Olavarría

Safaeian

2006

J of Comparative Neurology

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In normal rats callosal projections in striate cortex connect retinotopically corresponding, nonmirror-symmetric cortical loci, whereas in rats bilaterally enucleated at birth, callosal fibers connect topographically mismatched, mirror-symmetric loci. Moreover, retina input specifies the topography of callosal projections by postnatal day (P)6. To investigate whether retinal input guides development of callosal maps by promoting either the corrective pruning of exuberant axon branches or the specific ingrowth and elaboration of axon branches at topographically correct places, we studied the topography of emerging callosal connections at and immediately after P6. After restricted intracortical injections of anterogradely and retrogradely transported tracers we observed that the normal, nonmirror-symmetric callosal map, as well as the anomalous, mirror-symmetric map observed in neonatally enucleated animals, are present by P6-7, just as collateral branches of simple architecture emerge from their parental axons and grow into superficial cortical layers. Our results therefore do not support the idea that retinal input guides callosal map formation by primarily promoting the large-scale elimination of long, nontopographic branches and arbors. Instead, they suggest that retinal input specifies the sites on the parental axons from which interstitial branches will grow to invade middle and upper cortical layers, thereby ensuring that the location of invading interstitial branches is accurately related to the topographical location of the soma that gives rise to the parental axon. Moreover, our results from enucleated rats suggest that the cues that determine the mirror-symmetric callosal map exert only a weak control on the topography of fiber ingrowth.

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Callosal connections correlate preferentially with ipsilateral cortical domains in cat areas 17 and 18, and with contralateral domains in the 17/18 transition zone

Cited by 49 publications

References 53 publications

Retinal influences specify cortico‐cortical maps by postnatal day six in rats and mice

Retinal influences specify cortico‐cortical maps by postnatal day six in rats and mice

Interareal coordination of columnar architectures during visual cortical development

Development of callosal topography in visual cortex of normal and enucleated rats

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