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A simpler primate brain: the visual system of the marmoset monkey.

Solomon SG, Rosa MG - Front Neural Circuits (2014)

Bottom Line: Therefore, in order to understand some aspects of human visual function, we need to study non-human primate brains.Which species is the most appropriate model?Here we review the visual pathways of the marmoset, highlighting recent work that brings these advantages into focus, and identify where additional work needs to be done to link marmoset brain organization to that of macaques and humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University College London London, UK.

ABSTRACT
Humans are diurnal primates with high visual acuity at the center of gaze. Although primates share many similarities in the organization of their visual centers with other mammals, and even other species of vertebrates, their visual pathways also show unique features, particularly with respect to the organization of the cerebral cortex. Therefore, in order to understand some aspects of human visual function, we need to study non-human primate brains. Which species is the most appropriate model? Macaque monkeys, the most widely used non-human primates, are not an optimal choice in many practical respects. For example, much of the macaque cerebral cortex is buried within sulci, and is therefore inaccessible to many imaging techniques, and the postnatal development and lifespan of macaques are prohibitively long for many studies of brain maturation, plasticity, and aging. In these and several other respects the marmoset, a small New World monkey, represents a more appropriate choice. Here we review the visual pathways of the marmoset, highlighting recent work that brings these advantages into focus, and identify where additional work needs to be done to link marmoset brain organization to that of macaques and humans. We will argue that the marmoset monkey provides a good subject for studies of a complex visual system, which will likely allow an important bridge linking experiments in animal models to humans.

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Schematic organization of visual cortex in the marmoset. “Unfolded” representation prepared using the technique of Van Essen and Maunsell (1980). Discontinuities in the representation, introduced to minimize distortion, are indicated by the arrows. Continuous black lines indicate the main cortical folds, including the lips and fundi of the lateral and calcarine sulci, the fundi of the superior temporal and intraparietal dimples, and the limits of the medial, ventral, and orbital surfaces. The inset on the lower left shows a lateral view of the intact marmoset brain, with boundaries of some visual areas indicated to help orientation. Colors indicate visual areas that have been mapped using electrophysiological techniques; other areas are simply indicated by labels in their approximate location. For abbreviations, see legend of Figure 1. The light gray dashed outlines indicate the borders of the primary auditory (A1), motor (M1), and somatosensory (S1) areas, for orientation. The topographic organization of visual areas is indicated according to the following symbols: white squares, representations of the vertical meridian (VM); black circles, representations of the horizontal meridian (HM); “+,” representations of upper contralateral quadrant; “-,” representations of the lower contralateral quadrant; red dashed lines, isoeccentricity lines (numbers indicate eccentricity from the fovea, in degrees).
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Figure 5: Schematic organization of visual cortex in the marmoset. “Unfolded” representation prepared using the technique of Van Essen and Maunsell (1980). Discontinuities in the representation, introduced to minimize distortion, are indicated by the arrows. Continuous black lines indicate the main cortical folds, including the lips and fundi of the lateral and calcarine sulci, the fundi of the superior temporal and intraparietal dimples, and the limits of the medial, ventral, and orbital surfaces. The inset on the lower left shows a lateral view of the intact marmoset brain, with boundaries of some visual areas indicated to help orientation. Colors indicate visual areas that have been mapped using electrophysiological techniques; other areas are simply indicated by labels in their approximate location. For abbreviations, see legend of Figure 1. The light gray dashed outlines indicate the borders of the primary auditory (A1), motor (M1), and somatosensory (S1) areas, for orientation. The topographic organization of visual areas is indicated according to the following symbols: white squares, representations of the vertical meridian (VM); black circles, representations of the horizontal meridian (HM); “+,” representations of upper contralateral quadrant; “-,” representations of the lower contralateral quadrant; red dashed lines, isoeccentricity lines (numbers indicate eccentricity from the fovea, in degrees).

Mentions: The third tier visual areas are those that lie adjacent to the anterior border of V2, and in the marmoset these are exposed on the surface of the brain, rendering them more readily accessible to modern experimental techniques including multielectrode array recording, optogenetics, and imaging. Electrophysiological studies demonstrate at least two areas, each forming a near complete representation of the contralateral hemifield: areas DM (V6) and VLP (V3; Figure 5). Fragmentary evidence suggests the existence of at least one additional area, near the midline (19M; Figure 1). DM and VLP may also be separated by an anatomically distinct subdivision, the dorsointermediate area (DI; Krubitzer and Kaas, 1990; Rosa and Schmid, 1995; see Figure 1), about which virtually nothing is known.


A simpler primate brain: the visual system of the marmoset monkey.

Solomon SG, Rosa MG - Front Neural Circuits (2014)

Schematic organization of visual cortex in the marmoset. “Unfolded” representation prepared using the technique of Van Essen and Maunsell (1980). Discontinuities in the representation, introduced to minimize distortion, are indicated by the arrows. Continuous black lines indicate the main cortical folds, including the lips and fundi of the lateral and calcarine sulci, the fundi of the superior temporal and intraparietal dimples, and the limits of the medial, ventral, and orbital surfaces. The inset on the lower left shows a lateral view of the intact marmoset brain, with boundaries of some visual areas indicated to help orientation. Colors indicate visual areas that have been mapped using electrophysiological techniques; other areas are simply indicated by labels in their approximate location. For abbreviations, see legend of Figure 1. The light gray dashed outlines indicate the borders of the primary auditory (A1), motor (M1), and somatosensory (S1) areas, for orientation. The topographic organization of visual areas is indicated according to the following symbols: white squares, representations of the vertical meridian (VM); black circles, representations of the horizontal meridian (HM); “+,” representations of upper contralateral quadrant; “-,” representations of the lower contralateral quadrant; red dashed lines, isoeccentricity lines (numbers indicate eccentricity from the fovea, in degrees).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126041&req=5

Figure 5: Schematic organization of visual cortex in the marmoset. “Unfolded” representation prepared using the technique of Van Essen and Maunsell (1980). Discontinuities in the representation, introduced to minimize distortion, are indicated by the arrows. Continuous black lines indicate the main cortical folds, including the lips and fundi of the lateral and calcarine sulci, the fundi of the superior temporal and intraparietal dimples, and the limits of the medial, ventral, and orbital surfaces. The inset on the lower left shows a lateral view of the intact marmoset brain, with boundaries of some visual areas indicated to help orientation. Colors indicate visual areas that have been mapped using electrophysiological techniques; other areas are simply indicated by labels in their approximate location. For abbreviations, see legend of Figure 1. The light gray dashed outlines indicate the borders of the primary auditory (A1), motor (M1), and somatosensory (S1) areas, for orientation. The topographic organization of visual areas is indicated according to the following symbols: white squares, representations of the vertical meridian (VM); black circles, representations of the horizontal meridian (HM); “+,” representations of upper contralateral quadrant; “-,” representations of the lower contralateral quadrant; red dashed lines, isoeccentricity lines (numbers indicate eccentricity from the fovea, in degrees).
Mentions: The third tier visual areas are those that lie adjacent to the anterior border of V2, and in the marmoset these are exposed on the surface of the brain, rendering them more readily accessible to modern experimental techniques including multielectrode array recording, optogenetics, and imaging. Electrophysiological studies demonstrate at least two areas, each forming a near complete representation of the contralateral hemifield: areas DM (V6) and VLP (V3; Figure 5). Fragmentary evidence suggests the existence of at least one additional area, near the midline (19M; Figure 1). DM and VLP may also be separated by an anatomically distinct subdivision, the dorsointermediate area (DI; Krubitzer and Kaas, 1990; Rosa and Schmid, 1995; see Figure 1), about which virtually nothing is known.

Bottom Line: Therefore, in order to understand some aspects of human visual function, we need to study non-human primate brains.Which species is the most appropriate model?Here we review the visual pathways of the marmoset, highlighting recent work that brings these advantages into focus, and identify where additional work needs to be done to link marmoset brain organization to that of macaques and humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University College London London, UK.

ABSTRACT
Humans are diurnal primates with high visual acuity at the center of gaze. Although primates share many similarities in the organization of their visual centers with other mammals, and even other species of vertebrates, their visual pathways also show unique features, particularly with respect to the organization of the cerebral cortex. Therefore, in order to understand some aspects of human visual function, we need to study non-human primate brains. Which species is the most appropriate model? Macaque monkeys, the most widely used non-human primates, are not an optimal choice in many practical respects. For example, much of the macaque cerebral cortex is buried within sulci, and is therefore inaccessible to many imaging techniques, and the postnatal development and lifespan of macaques are prohibitively long for many studies of brain maturation, plasticity, and aging. In these and several other respects the marmoset, a small New World monkey, represents a more appropriate choice. Here we review the visual pathways of the marmoset, highlighting recent work that brings these advantages into focus, and identify where additional work needs to be done to link marmoset brain organization to that of macaques and humans. We will argue that the marmoset monkey provides a good subject for studies of a complex visual system, which will likely allow an important bridge linking experiments in animal models to humans.

Show MeSH
Related in: MedlinePlus