Structural organization of parallel information processing within the tectofugal visual system of the pigeon

Hellmann, Burkhard; Güntürkün, Onur

doi:10.1002/1096-9861(20000101)429:1<94::aid-cne8>3.0.co;2-5

Cited by 116 publications

(141 citation statements)

References 67 publications

(154 reference statements)

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“…Both nuclei receive their major input from the bilateral projection of the optic tectum [11,12]. It is this projection that might induce morphological asymmetries of the nucleus rotundus since the left nucleus rotundus receives stronger bilateral input than the right one [9].…”

Section: Discussionmentioning

confidence: 99%

A morphological study of the nucleus subpretectalis of the pigeon

Freund

Güntürkün

Manns

2008

Brain Research Bulletin

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In pigeons, the tectofugal system is functionally as well as structurally lateralized. So for example the right nucleus rotundus is less modulated by right forebrain influences than the left nucleus rotundus by the left ones. This functional lateralization pattern may depend on a dynamic balance between left and right tectal processing. Apart from inhibitory interactions at tectal level, suppressive influences might directly affect rotundal neurons by GABAergic input from a cluster of nuclei, the bed nuclei of the tecto-thalamic tract. A major afferent of these nuclei is the side branch of the tectorotundal projection which is of bilateral origin and which is involved in the regulation of ipsilateral as well as bilateral visual processing. Hence, an important role of the bed nuclei could be the interhemispheric communication and in turn the mediation of functional asymmetries. In a first step to unravel asymmetric influences of these nuclei, the present study investigated if the largest of the bed nuclei, the nucleus subpretectalis displays morphological asymmetries in the pigeon. We found that the nucleus subpretectalis in fact exhibits asymmetric cell sizes with larger cell bodies on the left side. This asymmetrical pattern was not present in dark-incubated animals indicating that cell size asymmetries within nucleus subpretectalis are induced by asymmetric photic stimulation during embryonic development.

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Section: Discussionmentioning

confidence: 99%

A morphological study of the nucleus subpretectalis of the pigeon

Freund

Güntürkün

Manns

2008

Brain Research Bulletin

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“…Such gain-control mechanisms are likely to affect brain areas further downstream. The HA of the Wulst sends an especially strong descending input on the optic tectum (Manns et al, 2007) with which it can regulate the tectofugal system (Hellmann and Güntürkün, 2001), the most prominent visual pathway in pigeons. When stimulated before the optic nerve, the Wulst can "sharpen" responses by dampening spontaneous activity in the optic tectum, possibly through the coactivation of local inhibitory circuits (Bagnoli et al, 1977).…”

Section: Rapid Adaptation: Possible Top-down Tectal Switch?mentioning

confidence: 99%

Dominant Vertical Orientation Processing without Clustered Maps: Early Visual Brain Dynamics Imaged with Voltage-Sensitive Dye in the Pigeon Visual Wulst

Ng¹,

Grabska-Barwińska²,

Güntürkün³

et al. 2010

J. Neurosci.

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The pigeon is a widely established behavioral model of visual cognition, but the processes along its most basic visual pathways remain mostly unexplored. Here, we report the neuronal population dynamics of the visual Wulst, an assumed homolog of the mammalian striate cortex, captured for the first time with voltage-sensitive dye imaging. Responses to drifting gratings were characterized by focal emergence of activity that spread extensively across the entire Wulst, followed by rapid adaptation that was most effective in the surround. Using additional electrophysiological recordings, we found cells that prefer a variety of orientations. However, analysis of the imaged spatiotemporal activation patterns revealed no clustered orientation map-like arrangements as typically found in the primary visual cortices of many mammalian species. Instead, the vertical orientation was overrepresented, both in terms of the imaged population signal, as well as the number of neurons preferring the vertical orientation. Such enhanced selectivity for the vertical orientation may result from horizontal motion vectors that trigger adaptation to the extensive flow field input during natural behavior. Our findings suggest that, although the avian visual Wulst is homologous to the primary visual cortex in terms of its gross anatomical connectivity and topology, its detailed operation and internal organization is still shaped according to specific input characteristics.

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“…Layers 8Á/12 were grouped as those retinoreceptive layers, which receive direct retinal input by ascending dendrites without projecting to the nucleus rotundus [19]. Layer 13 was separately analyzed since it constitutes the projection lamina to the rotundus [20].…”

Section: Neuroanatomymentioning

confidence: 99%

Embryonic light stimulation induces different asymmetries in visuoperceptual and visuomotor pathways of pigeons

Skiba

Diekamp

Güntürkün

2002

Behavioural Brain Research

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In birds, visual object discrimination performance is lateralized with a dominance of the right eye/left hemisphere. This asymmetry is induced by embryonic light stimulation. However, visually guided behavior, even during simple object distinction tasks, is composed of different behavioral and neural modules. Therefore, the aim of the present study was to test whether all neural subsystems involved in visual discriminations are lateralized in a similar way after prehatch visual stimulation. To examine this question, two behavioral paradigms were used which reveal complementary aspects of visually guided behavior. The first was the grain Á/grit discrimination task in which no left Á/right differences in the number of pecks, but significant differences in the number of grains can be found. Therefore, grain Á/grit discrimination reveals visuoperceptual performance but not visuomotor speed. The contrary seems to be the case for a successive pattern discrimination with a VR32 schedule. Here, the hemispheres do not differ with respect to discrimination accuracy but with regard to the number of pecks emitted. Thus, successive pattern discrimination with lean VR schedules reveals hemispheric differences in visuomotor speed without testing visuoperceptual performance. Using these two paradigms a group of light and a group of dark incubated pigeons were tested. The results show that dark incubated birds evinced no asymmetry in any measure while light incubated ones were right-eye dominant in both variables. However, light incubation induced a visual left hemispheric dominance by modulating two different processes, a left-hemispheric increase of visuoperceptual processes; and a right-hemispheric decrease for visuomotor speed. Taken together these data show that embryonic light stimulation elicits visual lateralization by differently modulating visuoperceptual and visuomotor systems in both hemispheres. #

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Structural organization of parallel information processing within the tectofugal visual system of the pigeon

Cited by 116 publications

References 67 publications

A morphological study of the nucleus subpretectalis of the pigeon

A morphological study of the nucleus subpretectalis of the pigeon

Dominant Vertical Orientation Processing without Clustered Maps: Early Visual Brain Dynamics Imaged with Voltage-Sensitive Dye in the Pigeon Visual Wulst

Embryonic light stimulation induces different asymmetries in visuoperceptual and visuomotor pathways of pigeons

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