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Features of the retinotopic representation in the visual wulst of a laterally eyed bird, the zebra finch (Taeniopygia guttata).

Michael N, Löwel S, Bischof HJ - PLoS ONE (2015)

Bottom Line: We found that the visual wulst can be activated by visual stimuli from a large part of the visual field of the contralateral eye.This confirms earlier electrophysiological studies indicating an inhibitory influence of the activation of the ipsilateral eye on wulst activity elicited by stimulating the contralateral eye.Instead, this brain area may be involved in the processing of visual information necessary for spatial orientation.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems Neuroscience, Johann-Friedrich-Blumenbach Institut für Zoologie und Anthropologie, Universität Göttingen, Göttingen, Germany; Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), Göttingen, Germany.

ABSTRACT
The visual wulst of the zebra finch comprises at least two retinotopic maps of the contralateral eye. As yet, it is not known how much of the visual field is represented in the wulst neuronal maps, how the organization of the maps is related to the retinal architecture, and how information from the ipsilateral eye is involved in the activation of the wulst. Here, we have used autofluorescent flavoprotein imaging and classical anatomical methods to investigate such characteristics of the most posterior map of the multiple retinotopic representations. We found that the visual wulst can be activated by visual stimuli from a large part of the visual field of the contralateral eye. Horizontally, the visual field representation extended from -5° beyond the beak tip up to +125° laterally. Vertically, a small strip from -10° below to about +25° above the horizon activated the visual wulst. Although retinal ganglion cells had a much higher density around the fovea and along a strip extending from the fovea towards the beak tip, these areas were not overrepresented in the wulst map. The wulst area activated from the foveal region of the ipsilateral eye, overlapped substantially with the middle of the three contralaterally activated regions in the visual wulst, and partially with the other two. Visual wulst activity evoked by stimulation of the frontal visual field was stronger with contralateral than with binocular stimulation. This confirms earlier electrophysiological studies indicating an inhibitory influence of the activation of the ipsilateral eye on wulst activity elicited by stimulating the contralateral eye. The lack of a foveal overrepresentation suggests that identification of objects may not be the primary task of the zebra finch visual wulst. Instead, this brain area may be involved in the processing of visual information necessary for spatial orientation.

No MeSH data available.


Related in: MedlinePlus

Ipsilateral foveal retinotopic map partially overlaps with contralateral one on the visual wulst.The azimuth and elevation maps obtained from the contralateral and the ipsilateral eye, when the respective eye was stimulated from an angle of 60° (foveal direction) and an overlay of the respective contralateral and ipsilateral activity maps are shown. The magnitude of activity is represented as a number in the upper right corner of the grey scale activity map (I-L). A—Positioning of the bird and the azimuth stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor from the eye was 30 cm in all cases. B—Positioning of the bird and the azimuth stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. C—Positioning of the bird and the elevation stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor was 30 cm in all cases. D—Positioning of the bird and the elevation stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. E and I—The azimuth polar map and grey scale activity map respectively, when the contralateral eye was stimulated with an azimuth stimulus. F and J—The azimuth polar map and grey scale activity map respectively, when the ipsilateral eye was stimulated. G and K—The elevation polar map and the grey scale activity map respectively, when the contralateral eye was stimulated with an elevation stimulus. H and L—The elevation polar map and the grey scale activity map respectively, when the ipsilateral eye was stimulated with an elevation stimulus. M—Superimposed mapping of the contralateral and the ipsilateral azimuth maps. N—Superimposed mapping of the contralateral and the ipsilateral elevation maps. M and N demonstrates the location of the ipsilateral map overlapping with the contralateral map. Scale bar = 500 μm.
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pone.0124917.g009: Ipsilateral foveal retinotopic map partially overlaps with contralateral one on the visual wulst.The azimuth and elevation maps obtained from the contralateral and the ipsilateral eye, when the respective eye was stimulated from an angle of 60° (foveal direction) and an overlay of the respective contralateral and ipsilateral activity maps are shown. The magnitude of activity is represented as a number in the upper right corner of the grey scale activity map (I-L). A—Positioning of the bird and the azimuth stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor from the eye was 30 cm in all cases. B—Positioning of the bird and the azimuth stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. C—Positioning of the bird and the elevation stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor was 30 cm in all cases. D—Positioning of the bird and the elevation stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. E and I—The azimuth polar map and grey scale activity map respectively, when the contralateral eye was stimulated with an azimuth stimulus. F and J—The azimuth polar map and grey scale activity map respectively, when the ipsilateral eye was stimulated. G and K—The elevation polar map and the grey scale activity map respectively, when the contralateral eye was stimulated with an elevation stimulus. H and L—The elevation polar map and the grey scale activity map respectively, when the ipsilateral eye was stimulated with an elevation stimulus. M—Superimposed mapping of the contralateral and the ipsilateral azimuth maps. N—Superimposed mapping of the contralateral and the ipsilateral elevation maps. M and N demonstrates the location of the ipsilateral map overlapping with the contralateral map. Scale bar = 500 μm.

Mentions: First, the stimulus monitor was positioned at +60° (right visual field, right eye stimulation) or—60° (left visual field, left eye stimulation), and azimuth (Fig 9A and 9B) or elevation stimuli (Fig 9C and 9D) were presented. Activity was recorded in the left visual wulst. Interestingly, contralateral eye stimulation in this bird evoked multiple retinotopic maps after both azimuth and elevation stimuli (Fig 9E and 9G). While in the azimuth map (Fig 9E) separation of the different maps is difficult, there were clearly 3 separate maps in the elevation map, with the anterior two maps being inverted with respect to the posterior map, (Fig 9G). Wulst activation induced by stimulating the ipsilateral eye was weaker and more restricted in the posterior two maps (compare Fig 9I with 9J and 9K with 9L). The pink color in Fig 9F indicates that ipsilateral activation was induced by stimuli at around 50° to 40° azimuth in the left visual field. The activity patches induced by contralateral azimuth stimuli did not differ from those induced by elevation stimuli. The same was true for activation induced by azimuth and elevation stimuli via the ipsilateral eye. Fig 9M and 9N illustrates the superimposition of thresholded contra- (red) and ipsilaterally (green) evoked activity regions. It can easily be seen that there are separate areas activated by the contra- and ipsilateral eye, but there was also substantial overlap in the middle and the most posterior activated regions, visible as yellow patches in Fig 9M and 9N.


Features of the retinotopic representation in the visual wulst of a laterally eyed bird, the zebra finch (Taeniopygia guttata).

Michael N, Löwel S, Bischof HJ - PLoS ONE (2015)

Ipsilateral foveal retinotopic map partially overlaps with contralateral one on the visual wulst.The azimuth and elevation maps obtained from the contralateral and the ipsilateral eye, when the respective eye was stimulated from an angle of 60° (foveal direction) and an overlay of the respective contralateral and ipsilateral activity maps are shown. The magnitude of activity is represented as a number in the upper right corner of the grey scale activity map (I-L). A—Positioning of the bird and the azimuth stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor from the eye was 30 cm in all cases. B—Positioning of the bird and the azimuth stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. C—Positioning of the bird and the elevation stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor was 30 cm in all cases. D—Positioning of the bird and the elevation stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. E and I—The azimuth polar map and grey scale activity map respectively, when the contralateral eye was stimulated with an azimuth stimulus. F and J—The azimuth polar map and grey scale activity map respectively, when the ipsilateral eye was stimulated. G and K—The elevation polar map and the grey scale activity map respectively, when the contralateral eye was stimulated with an elevation stimulus. H and L—The elevation polar map and the grey scale activity map respectively, when the ipsilateral eye was stimulated with an elevation stimulus. M—Superimposed mapping of the contralateral and the ipsilateral azimuth maps. N—Superimposed mapping of the contralateral and the ipsilateral elevation maps. M and N demonstrates the location of the ipsilateral map overlapping with the contralateral map. Scale bar = 500 μm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4390349&req=5

pone.0124917.g009: Ipsilateral foveal retinotopic map partially overlaps with contralateral one on the visual wulst.The azimuth and elevation maps obtained from the contralateral and the ipsilateral eye, when the respective eye was stimulated from an angle of 60° (foveal direction) and an overlay of the respective contralateral and ipsilateral activity maps are shown. The magnitude of activity is represented as a number in the upper right corner of the grey scale activity map (I-L). A—Positioning of the bird and the azimuth stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor from the eye was 30 cm in all cases. B—Positioning of the bird and the azimuth stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. C—Positioning of the bird and the elevation stimulus monitor when the contralateral eye was stimulated. The left eye was closed using a blind, the monitor was placed at 60° with respect to the right eye and the distance of the monitor was 30 cm in all cases. D—Positioning of the bird and the elevation stimulus monitor when the ipsilateral eye was stimulated. The right eye was closed using a blind; the monitor was placed at 60° with respect to the left eye. E and I—The azimuth polar map and grey scale activity map respectively, when the contralateral eye was stimulated with an azimuth stimulus. F and J—The azimuth polar map and grey scale activity map respectively, when the ipsilateral eye was stimulated. G and K—The elevation polar map and the grey scale activity map respectively, when the contralateral eye was stimulated with an elevation stimulus. H and L—The elevation polar map and the grey scale activity map respectively, when the ipsilateral eye was stimulated with an elevation stimulus. M—Superimposed mapping of the contralateral and the ipsilateral azimuth maps. N—Superimposed mapping of the contralateral and the ipsilateral elevation maps. M and N demonstrates the location of the ipsilateral map overlapping with the contralateral map. Scale bar = 500 μm.
Mentions: First, the stimulus monitor was positioned at +60° (right visual field, right eye stimulation) or—60° (left visual field, left eye stimulation), and azimuth (Fig 9A and 9B) or elevation stimuli (Fig 9C and 9D) were presented. Activity was recorded in the left visual wulst. Interestingly, contralateral eye stimulation in this bird evoked multiple retinotopic maps after both azimuth and elevation stimuli (Fig 9E and 9G). While in the azimuth map (Fig 9E) separation of the different maps is difficult, there were clearly 3 separate maps in the elevation map, with the anterior two maps being inverted with respect to the posterior map, (Fig 9G). Wulst activation induced by stimulating the ipsilateral eye was weaker and more restricted in the posterior two maps (compare Fig 9I with 9J and 9K with 9L). The pink color in Fig 9F indicates that ipsilateral activation was induced by stimuli at around 50° to 40° azimuth in the left visual field. The activity patches induced by contralateral azimuth stimuli did not differ from those induced by elevation stimuli. The same was true for activation induced by azimuth and elevation stimuli via the ipsilateral eye. Fig 9M and 9N illustrates the superimposition of thresholded contra- (red) and ipsilaterally (green) evoked activity regions. It can easily be seen that there are separate areas activated by the contra- and ipsilateral eye, but there was also substantial overlap in the middle and the most posterior activated regions, visible as yellow patches in Fig 9M and 9N.

Bottom Line: We found that the visual wulst can be activated by visual stimuli from a large part of the visual field of the contralateral eye.This confirms earlier electrophysiological studies indicating an inhibitory influence of the activation of the ipsilateral eye on wulst activity elicited by stimulating the contralateral eye.Instead, this brain area may be involved in the processing of visual information necessary for spatial orientation.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems Neuroscience, Johann-Friedrich-Blumenbach Institut für Zoologie und Anthropologie, Universität Göttingen, Göttingen, Germany; Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), Göttingen, Germany.

ABSTRACT
The visual wulst of the zebra finch comprises at least two retinotopic maps of the contralateral eye. As yet, it is not known how much of the visual field is represented in the wulst neuronal maps, how the organization of the maps is related to the retinal architecture, and how information from the ipsilateral eye is involved in the activation of the wulst. Here, we have used autofluorescent flavoprotein imaging and classical anatomical methods to investigate such characteristics of the most posterior map of the multiple retinotopic representations. We found that the visual wulst can be activated by visual stimuli from a large part of the visual field of the contralateral eye. Horizontally, the visual field representation extended from -5° beyond the beak tip up to +125° laterally. Vertically, a small strip from -10° below to about +25° above the horizon activated the visual wulst. Although retinal ganglion cells had a much higher density around the fovea and along a strip extending from the fovea towards the beak tip, these areas were not overrepresented in the wulst map. The wulst area activated from the foveal region of the ipsilateral eye, overlapped substantially with the middle of the three contralaterally activated regions in the visual wulst, and partially with the other two. Visual wulst activity evoked by stimulation of the frontal visual field was stronger with contralateral than with binocular stimulation. This confirms earlier electrophysiological studies indicating an inhibitory influence of the activation of the ipsilateral eye on wulst activity elicited by stimulating the contralateral eye. The lack of a foveal overrepresentation suggests that identification of objects may not be the primary task of the zebra finch visual wulst. Instead, this brain area may be involved in the processing of visual information necessary for spatial orientation.

No MeSH data available.


Related in: MedlinePlus