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Distribution of cortical neurons projecting to the superior colliculus in macaque monkeys.

Cerkevich CM, Lyon DC, Balaram P, Kaas JH - Eye Brain (2014)

Bottom Line: To isolate inputs to the purely visual layers in the superficial SC from those inputs to the motor and multisensory layers deeper in the SC, two injections were placed to include the intermediate and deep layers of the SC.In another case, an injection was placed in the medial pulvinar, a nucleus not known to be strongly connected with visual cortex, to identify possible projections from tracer spread past the lateral boundary of the SC.Four conclusions are supported by the results: 1) all early visual areas of cortex, including V1, V2, V3, and the middle temporal area, project to the superficial layers of the SC; 2) with the possible exception of the frontal eye field, few areas of cortex outside of the early visual areas project to the superficial SC, although many do, however, project to the intermediate and deep layers of the SC; 3) roughly matching retinotopy is conserved in the projections of visual areas to the SC; and 4) the projections from different visual areas are similarly dense, although projections from early visual areas appear somewhat denser than those of higher order visual areas in macaque cortex.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, University of Pittsburgh School of Medicine, Systems Neuroscience Institute, Pittsburgh, PA, USA.

ABSTRACT

To better reveal the pattern of corticotectal projections to the superficial layers of the superior colliculus (SC), we made a total of ten retrograde tracer injections into the SC of three macaque monkeys (Macaca mulatta). The majority of these injections were in the superficial layers of the SC, which process visual information. To isolate inputs to the purely visual layers in the superficial SC from those inputs to the motor and multisensory layers deeper in the SC, two injections were placed to include the intermediate and deep layers of the SC. In another case, an injection was placed in the medial pulvinar, a nucleus not known to be strongly connected with visual cortex, to identify possible projections from tracer spread past the lateral boundary of the SC. Four conclusions are supported by the results: 1) all early visual areas of cortex, including V1, V2, V3, and the middle temporal area, project to the superficial layers of the SC; 2) with the possible exception of the frontal eye field, few areas of cortex outside of the early visual areas project to the superficial SC, although many do, however, project to the intermediate and deep layers of the SC; 3) roughly matching retinotopy is conserved in the projections of visual areas to the SC; and 4) the projections from different visual areas are similarly dense, although projections from early visual areas appear somewhat denser than those of higher order visual areas in macaque cortex.

No MeSH data available.


Related in: MedlinePlus

case 1 Frontal cortexNotes: (A) Cortical region denoted as frontal cortex in macaques is indicated by dotted line. (B) Top-down view of the reconstructed case 1 injection sites in the SC. Left is medial, rostral is up. (C) Distribution of cells through the frontal cortex in case 1. Areal boundaries were determined from adjacent sections stained for cytochrome oxidase and myelin. The depths of the central and principal sulci are shaded in light gray. (D–F) Closer view of cells labeled by each tracer around the arcuate sulcus. (G) Closer view of double-labeled cells in the boxed region. In cortex, right is rostral, up is medial. Scale bar is 5 mm.Abbreviations: AS, arcuate sulcus; CgS, cingulate sulcus; CS, central sulcus; DL, dorsolateral area; DY, diamidino yellow; FB, fast blue; FEF, frontal eye field; FR, Fluororuby; IPS, intraparietal sulcus; LS, lateral sulcus; LuS, lunate sulcus; MOS, medial orbital sulcus; PS, principal sulcus; Pul, pulvinar; SC, superior colliculus; STS, superior temporal sulcus.
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Figure 8: case 1 Frontal cortexNotes: (A) Cortical region denoted as frontal cortex in macaques is indicated by dotted line. (B) Top-down view of the reconstructed case 1 injection sites in the SC. Left is medial, rostral is up. (C) Distribution of cells through the frontal cortex in case 1. Areal boundaries were determined from adjacent sections stained for cytochrome oxidase and myelin. The depths of the central and principal sulci are shaded in light gray. (D–F) Closer view of cells labeled by each tracer around the arcuate sulcus. (G) Closer view of double-labeled cells in the boxed region. In cortex, right is rostral, up is medial. Scale bar is 5 mm.Abbreviations: AS, arcuate sulcus; CgS, cingulate sulcus; CS, central sulcus; DL, dorsolateral area; DY, diamidino yellow; FB, fast blue; FEF, frontal eye field; FR, Fluororuby; IPS, intraparietal sulcus; LS, lateral sulcus; LuS, lunate sulcus; MOS, medial orbital sulcus; PS, principal sulcus; Pul, pulvinar; SC, superior colliculus; STS, superior temporal sulcus.

Mentions: The only area outside of the visual cortex and posterior parietal cortex that contained label after injection of tracers into the SC was the FEF of the frontal cortex (Figure 8). Like visual areas of cortex, the visuomotor area FEF is topographically arranged, with central vision being represented laterally and peripheral vision medially.34 Both DY and FR injections overlapped in the colliculus, and, as a result, neurons labeled by these injections overlapped in the FEF (Figure 8C and D for DY alone, and E for FR alone). Most of the cells labeled by these injections were concentrated along the arcuate sulcus, lateral to the tip of the principal sulcus. The DY-filled neurons covered a larger extent of the arcuate sulcus, likely due to the larger medial–lateral spread of this injection. The location of the FR- and DY-filled cells appeared to be roughly topographically matched to the retinotopic location of the SC injections. The widespread FB injection covered the rostral half of the SC, but was too superficial to label many neurons in the FEF. The FB labeled cells resulting from the injection were slightly anterior to cells labeled by the FR and DY injection (Figure 8C), but also centered laterally (Figure 8F). There were also cells labeled by the FB injection outside of the FEF in the lower bank of the principal sulcus. The widespread FB injection spread into the pretectum and the caudal pulvinar. Labeled neurons in two locations of the lateral prefrontal cortex were likely labeled by the spread of the tracers into the pulvinar.6,31 As with visual cortex, the retinotopic location of double-labeled cells roughly matched the location of overlap of the injections (Figure 8G).


Distribution of cortical neurons projecting to the superior colliculus in macaque monkeys.

Cerkevich CM, Lyon DC, Balaram P, Kaas JH - Eye Brain (2014)

case 1 Frontal cortexNotes: (A) Cortical region denoted as frontal cortex in macaques is indicated by dotted line. (B) Top-down view of the reconstructed case 1 injection sites in the SC. Left is medial, rostral is up. (C) Distribution of cells through the frontal cortex in case 1. Areal boundaries were determined from adjacent sections stained for cytochrome oxidase and myelin. The depths of the central and principal sulci are shaded in light gray. (D–F) Closer view of cells labeled by each tracer around the arcuate sulcus. (G) Closer view of double-labeled cells in the boxed region. In cortex, right is rostral, up is medial. Scale bar is 5 mm.Abbreviations: AS, arcuate sulcus; CgS, cingulate sulcus; CS, central sulcus; DL, dorsolateral area; DY, diamidino yellow; FB, fast blue; FEF, frontal eye field; FR, Fluororuby; IPS, intraparietal sulcus; LS, lateral sulcus; LuS, lunate sulcus; MOS, medial orbital sulcus; PS, principal sulcus; Pul, pulvinar; SC, superior colliculus; STS, superior temporal sulcus.
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Figure 8: case 1 Frontal cortexNotes: (A) Cortical region denoted as frontal cortex in macaques is indicated by dotted line. (B) Top-down view of the reconstructed case 1 injection sites in the SC. Left is medial, rostral is up. (C) Distribution of cells through the frontal cortex in case 1. Areal boundaries were determined from adjacent sections stained for cytochrome oxidase and myelin. The depths of the central and principal sulci are shaded in light gray. (D–F) Closer view of cells labeled by each tracer around the arcuate sulcus. (G) Closer view of double-labeled cells in the boxed region. In cortex, right is rostral, up is medial. Scale bar is 5 mm.Abbreviations: AS, arcuate sulcus; CgS, cingulate sulcus; CS, central sulcus; DL, dorsolateral area; DY, diamidino yellow; FB, fast blue; FEF, frontal eye field; FR, Fluororuby; IPS, intraparietal sulcus; LS, lateral sulcus; LuS, lunate sulcus; MOS, medial orbital sulcus; PS, principal sulcus; Pul, pulvinar; SC, superior colliculus; STS, superior temporal sulcus.
Mentions: The only area outside of the visual cortex and posterior parietal cortex that contained label after injection of tracers into the SC was the FEF of the frontal cortex (Figure 8). Like visual areas of cortex, the visuomotor area FEF is topographically arranged, with central vision being represented laterally and peripheral vision medially.34 Both DY and FR injections overlapped in the colliculus, and, as a result, neurons labeled by these injections overlapped in the FEF (Figure 8C and D for DY alone, and E for FR alone). Most of the cells labeled by these injections were concentrated along the arcuate sulcus, lateral to the tip of the principal sulcus. The DY-filled neurons covered a larger extent of the arcuate sulcus, likely due to the larger medial–lateral spread of this injection. The location of the FR- and DY-filled cells appeared to be roughly topographically matched to the retinotopic location of the SC injections. The widespread FB injection covered the rostral half of the SC, but was too superficial to label many neurons in the FEF. The FB labeled cells resulting from the injection were slightly anterior to cells labeled by the FR and DY injection (Figure 8C), but also centered laterally (Figure 8F). There were also cells labeled by the FB injection outside of the FEF in the lower bank of the principal sulcus. The widespread FB injection spread into the pretectum and the caudal pulvinar. Labeled neurons in two locations of the lateral prefrontal cortex were likely labeled by the spread of the tracers into the pulvinar.6,31 As with visual cortex, the retinotopic location of double-labeled cells roughly matched the location of overlap of the injections (Figure 8G).

Bottom Line: To isolate inputs to the purely visual layers in the superficial SC from those inputs to the motor and multisensory layers deeper in the SC, two injections were placed to include the intermediate and deep layers of the SC.In another case, an injection was placed in the medial pulvinar, a nucleus not known to be strongly connected with visual cortex, to identify possible projections from tracer spread past the lateral boundary of the SC.Four conclusions are supported by the results: 1) all early visual areas of cortex, including V1, V2, V3, and the middle temporal area, project to the superficial layers of the SC; 2) with the possible exception of the frontal eye field, few areas of cortex outside of the early visual areas project to the superficial SC, although many do, however, project to the intermediate and deep layers of the SC; 3) roughly matching retinotopy is conserved in the projections of visual areas to the SC; and 4) the projections from different visual areas are similarly dense, although projections from early visual areas appear somewhat denser than those of higher order visual areas in macaque cortex.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, University of Pittsburgh School of Medicine, Systems Neuroscience Institute, Pittsburgh, PA, USA.

ABSTRACT

To better reveal the pattern of corticotectal projections to the superficial layers of the superior colliculus (SC), we made a total of ten retrograde tracer injections into the SC of three macaque monkeys (Macaca mulatta). The majority of these injections were in the superficial layers of the SC, which process visual information. To isolate inputs to the purely visual layers in the superficial SC from those inputs to the motor and multisensory layers deeper in the SC, two injections were placed to include the intermediate and deep layers of the SC. In another case, an injection was placed in the medial pulvinar, a nucleus not known to be strongly connected with visual cortex, to identify possible projections from tracer spread past the lateral boundary of the SC. Four conclusions are supported by the results: 1) all early visual areas of cortex, including V1, V2, V3, and the middle temporal area, project to the superficial layers of the SC; 2) with the possible exception of the frontal eye field, few areas of cortex outside of the early visual areas project to the superficial SC, although many do, however, project to the intermediate and deep layers of the SC; 3) roughly matching retinotopy is conserved in the projections of visual areas to the SC; and 4) the projections from different visual areas are similarly dense, although projections from early visual areas appear somewhat denser than those of higher order visual areas in macaque cortex.

No MeSH data available.


Related in: MedlinePlus