Patterns of interhemispheric and striate-peristriate connections in visual cortex of the South American marsupial Marmosa elegans (mouse opossum)

Bravo, Hermes; Olavarría, Jaime F.; Martinich, Santiago

doi:10.1007/bf00186465

Cited by 15 publications

(18 citation statements)

References 24 publications

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“…Benevento and Ebner (1971) demonstrated V1 projections to these same regions in a n earlier degeneration study, as have Bravo et al (1990) in mouse opossums. These findings suggest that opossums have V1, V2, and at least two other visual areas and that most or all of the cortex between V2 and the somatosensory areas is visual.…”

Section: Visual and Auditory Regionsmentioning

confidence: 79%

“…An injection into rostromedial V1 labeled neurons and terminals in several patches in rostral V2. Benevento and Ebner (1971) reported that the rostral striate cortex of opossums projects to the rostral peristriate cortex, whereas the caudal striate cortex projects to the caudal peristriate cortex, a pattern consistent with the concept of V2 (also see Bravo et al, 1990). The V2 region has uneven connections with the visual cortex of the other hemisphere (Granger et al, 1985;Cusick and Kaas, 1986) so that V2 contains a series of ovals of sparse interhemispheric connections separated by narrow zones with dense connections.…”

Section: Visual and Auditory Regionsmentioning

confidence: 84%

“…The V2 region has uneven connections with the visual cortex of the other hemisphere (Granger et al, 1985;Cusick and Kaas, 1986) so that V2 contains a series of ovals of sparse interhemispheric connections separated by narrow zones with dense connections. In the mouse opossum, Marmaso elegans, Bravo et al (1990) showed that V1 projections are largely confined to the ovals, demonstrating a type of modular organization that is also seen in V2 of other mammals such as tree shrews (Cusick et al, 1985).…”

Section: Visual and Auditory Regionsmentioning

confidence: 96%

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Topography, architecture, and connections of somatosensory cortex in opossums: Evidence for five somatosensory areas

1996

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Microelectrode maps of somatosensory inputs were related to cortical architecture and patterns of cortical connections to provide evidence for five subdivisions of the somatosensory or sensorimotor cortex in North American opossums (Didelphis marsupialis). Microelectrode recordings revealed three systematic representations of the body surface. A large mediolaterally oriented representation was identified as the primary somatosensory area (S1) by its relative position, somatotopy, architecture, and connections. S1 represented the hindlimb, trunk, forelimb, and face in a mediolateral sequence. Two additional representations of cutaneous receptors were found caudolateral to S1, each with face representations adjacent to the border of lateral S1 and other body-part representations progressing more caudally toward the auditory cortex. We identified the more dorsal field as the second somatosensory area (S2) and the more ventral field as the parietal ventral area (PV). Tracers injected into S1 labeled neurons and terminals in architectonically distinct fields rostral and caudal to S1, the somatosensory caudal area (SC) and the somatosensory rostral area (SR). Movements could be evoked by microstimulation from sites scattered over S1, SR, and the frontal cortex, but thresholds were high and uncharacteristic of motor cortex. S2 and PV merged caudally with the cortex responsive to auditory stimuli, possibly A1, and neurons in some caudal recording sites in PV were activated by both auditory and cutaneous stimuli. Primary (V1) and secondary (V2) visual areas were also identified by microelectrode mapping, architecture, and connections. In addition, at least part of the cortex between V2 and the somatosensory cortex had visual connections. Thus, most of the dorsolateral cortex of opossums appears to be somatosensory, auditory, or visual.

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Section: Visual and Auditory Regionsmentioning

confidence: 79%

Section: Visual and Auditory Regionsmentioning

confidence: 84%

Section: Visual and Auditory Regionsmentioning

confidence: 96%

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Topography, architecture, and connections of somatosensory cortex in opossums: Evidence for five somatosensory areas

1996

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“…Neurons in V2 have large receptive fields and a reversal in retinotopy is observed at the V1/V2 boundary [Kahn et al, 2000]. Neuroanatomical studies of cortical connections in short-tailed opossums [Kahn et al, 2000] produced similar results to those from studies of brush-tailed possums [Crewther et al, 1984], South American opossums [Martinich et al, 2000], Virginia opossum [Benevento and Ebner, 1971] and mouse opossums [Bravo et al, 1990]. Namely, connections are observed between V1 and the presumptive location of V2, which is immediately rostrolateral to V1.…”

Section: Discussionmentioning

confidence: 93%

An Architectonic Study of the Neocortex of the Short-Tailed Opossum <i>(Monodelphis domestica)</i>

Wong

Kaas²

2009

Brain Behav Evol

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Short-tailed opossums (Monodelphis domestica) belong to the branch of marsupial mammals that diverged from eutherian mammals approximately 180 million years ago. They are small in size, lack a marsupial pouch, and may have retained more morphological characteristics of early marsupial neocortex than most other marsupials. In the present study, we used several different histochemical and immunochemical procedures to reveal the architectonic characteristics of cortical areas in short-tailed opossums. Subdivisions of cortex were identified in brain sections cut in the coronal, sagittal, horizontal or tangential planes and processed for a calcium-binding protein, parvalbumin (PV), neurofilament protein epitopes recognized by SMI-32, the vesicle glutamate transporter 2 (VGluT2), myelin, cytochrome oxidase (CO), and Nissl substance. These different procedures revealed similar boundaries among areas, suggesting that functionally relevant borders were detected. The results allowed a fuller description and more precise demarcation of previously identified sensory areas, and the delineation of additional subdivisions of cortex. Area 17 (V1) was especially prominent, with a densely populated layer 4, high myelination levels, and dark staining of PV and VGluT2 immunopositive terminations. These architectonic features were present, albeit less pronounced, in somatosensory and auditory cortex. The major findings support the conclusion that short-tailed opossums have fewer cortical areas and their neocortex is less distinctly laminated than most other mammals.

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“…Callosal bridges similar to those spanning cat area 18 have been described in marsupials (Benevento and Ebner, 1971;Bravo et al, 1990b), rodents (Cusick and Lund, 1981;Montero, 1984, 1990;Bravo et al, 1990a), and tree shrews (Cusick et al, 1985). At least in marsupials and rodents, bridges across area 18a appear to correspond to borders of extrastriate visual areas (Benevento and Ebner, 1971;Montero, 1984, 1990;Bravo et al, 1990a,b).…”

Section: Normal Catsmentioning

confidence: 90%

Overall pattern of callosal connections in visual cortex of normal and enucleated cats

Olavarría

Sluyters

1995

J of Comparative Neurology

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The effect of neonatal bilateral enucleation on the overall distribution of callosal connections in striate and extrastriate visual cortex of the cat was studied using tangential sections from the physically unfolded and flattened cortex. Callosal neurons were labeled by administering the anatomical tracer horseradish peroxidase directly to the transected corpus callosum. The pattern of callosal connections in binocularly enucleated cats showed both consistent differences and consistent similarities with the pattern in normal cats. In agreement with previous studies, it was found that callosal labeling at the 17/18 border of enucleated cats was considerably sparser than in normal cats. Moreover, we found that the strip containing the majority of labeled cells at the 17/18 border was narrower than in normal cats. In both normal and enucleated cats, scattered cells were distributed on either side of the 17/18 callosal strip, well into areas 17 and 18. In much of extrastriate cortex, the pattern of callosal connectivity in enucleated cats looked surprisingly normal. Details of the callosal pattern that were consistently found in normal cats could also be recognized in binocularly enucleated cats, such as two to four bridges of labeling spanning areas 18 and 19. Also, four zones that were free of callosal connectivity in area 7, on the banks of the suprasylvian sulcus, and in the posterior suprasylvian sulcus were found in both normal and enucleated cats. Finally, as in normal cats, dense cell labeling occurred on the crown of the suprasylvian gyrus at its posterior end, from which it extended laterally across both banks of the suprasylvian sulcus and into the fundus of this sulcus. The results of this study suggest that, although the stabilization of callosal connections at the 17/18 border region appears to depend on visual input, this input plays a less prominent role in the stabilization of callosal connections in extrastriate visual cortex.

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Patterns of interhemispheric and striate-peristriate connections in visual cortex of the South American marsupial Marmosa elegans (mouse opossum)

Cited by 15 publications

References 24 publications

Topography, architecture, and connections of somatosensory cortex in opossums: Evidence for five somatosensory areas

Topography, architecture, and connections of somatosensory cortex in opossums: Evidence for five somatosensory areas

An Architectonic Study of the Neocortex of the Short-Tailed Opossum <i>(Monodelphis domestica)</i>

Overall pattern of callosal connections in visual cortex of normal and enucleated cats

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