Internal structure of the nucleus rotundus revealed by mapping cadherin expression in the embryonic chicken visual system

Abstract

The nucleus rotundus is the largest nucleus of the avian thalamus. It is an important center of visual information processing and conveys information from the optic tectum to the ectostriatum in the telencephalon. The nucleus rotundus is generally believed to contain internal divisions processing information on color, form, motion, and looming of visual objects. The detailed arrangement of these internal divisions is unclear. Here, we map the expression of four classic cadherins (N-cadherin, R-cadherin, cadherin-6B, and cadherin-7), which are markers for specific functional gray matter divisions and their fiber connections in the vertebrate brain. Results show that each cadherin is expressed by one coherent part of the nucleus rotundus that is connected to other brain structures by fiber tracts expressing the same subtype of cadherin. Overall, the expression of the four cadherins encompasses almost the entire nucleus rotundus. The four cadherin-expressing parts show different degrees of overlap. For example, the cadherin-6B part and the cadherin-7 part overlap extensively, whereas the R-cadherin part and the cadherin-6B part show little overlap and are partially complementary. Regions with shallow gradients of cadherin expression alternate with regions that show relatively abrupt changes in cadherin expression. At some points, changes of cadherin expression are also arranged in a pinwheel-like fashion, alternating between clockwise and counterclockwise orientations. In general, these results are reminiscent of the organization of functional modules in the mammalian visual cortex. It is speculated that each domain of cadherin expression corresponds to a functional domain, which processes a specific stimulus feature.

OL‐protocadherin expression in the visual system of the chicken embryo

“…5C,G), cad7, and cad6B ( Fig. 5D,H; Redies et al, 2000;Becker and Redies, 2003), although partial overlap is observed. An OLpcad-positive fiber fascicle can be followed from an OLpcad-positive, ventrocaudal region of the rotundus into the ventral supraoptic decussation (dsv in Figs.…”

“…The corresponding molecule was studied previously in the mouse brain and was found to be expressed predominantly in the olfactory and limbic systems (hence the name OL-protocadherin; Hirano et al, 1999b;Aoki et al, 2003). Here we concentrated on the expression of OLpcad in the visual system of the chicken embryo, because 1) the OLpcad expression in this system is particularly prominent, 2) the components of this system are distinct and well known, and 3) our results can be compared with the expression of classic cadherins mapped previously in the visual system of the chicken embryo (Wöhrn et al, 1998(Wöhrn et al, , 1999Becker and Redies, 2003).…”

“…It has been shown previously that these central parts of the visual system express differentially members of a family of cell adhesion molecules, the cadherins (Redies et al, 1993;Miskevich et al, 1998;Wöhrn et al, 1998Wöhrn et al, , 1999Treubert-Zimmermann et al, 2002;Becker and Redies, 2003). Cadherins are Ca 2ϩ -dependent cell-surface glycoproteins that regulate cell binding in a preferentially homotypic fashion.…”

Definition and novel connections of the entopallium in the pigeon (Columba livia)

“…This division of the pigeon entopallium into internal and external parts, a division that is also present in the zebra finch (Krü tzfeldt , may reflect a fundamental aspect of entopallial organization in birds. How this division might relate to other parcelations of the nucleus, such as that elucidated by Benowitz and Karten (1976) on the basis of multiple channels of rotundal input or that proposed by Nguyen et al (2004) on the basis of neurobehavioral evidence, is not clear, nor is it clear how this division relates to the anatomical and physiological complexities of the input nucleus rotundus, such as have been defined on the basis of differential staining for AChE or cadherin expression (Martinez-de-la-Torre et al 1990;Becker and Redies, 2003), differential patterns of tectal input (Marin et al, 2003), or differential physiology (Wang and Frost, 1992;Wang et al 1993). It will be particularly interesting to determine, for instance, whether the internal and external entopallial divisions receive a similar or a different pattern of inputs from the various rotundal subdivisions, and whether the physiology of the neurons in each of the two entopallial divisions reflects these differential inputs.…”

Differential expression of protocadherin‐19, protocadherin‐17, and cadherin‐6 in adult zebrafish brain

“…There are numerous reports on expression of these cadherins in embryonic vertebrate CNS (Wohrn et al, 1998, 1999; Redies et al, 2001; Becker and Redies, 2003; Luo et al, 2004; Gaitan and Bouchard, 2006; Liu et al, 2006; Emond et al, 2009; Tai et al, 2010; Liu et al, 2010; Terakawa et al, 2013), but only a few on their distribution in the brain of adult vertebrates (Dean et al, 2007; Kim et al, 2007; Hertel et al, 2008, 2012; Hertel and Redies, 2011; Stoya et al, 2014). Moreover, studies on their expression in the adult brains focus mainly on a subset of brain structures (e.g.…”