The subrhinal paleocortex in the hedgehog tenrec: a multiarchitectonic characterization and an analysis of its connections with the olfactory bulb

Künzle, Heinz; Radtke‐Schuller, Susanne

doi:10.1007/s004290000137

Cited by 15 publications

(18 citation statements)

References 81 publications

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“…In both monotremes the OT is small and poorly developed; in the platypus this means small in absolute terms (less than 1.5 mm eutheria occupying a similar insectivorous niche [Künzle and Radtke-Schuller, 2000]. As previously reported [Ashwell, 2006], the olfactory bulb of the echidna is comparable in volume to prosimians of similar body weight and comparable in absolute terms to the volume of the olfactory bulbs of the largest eutherian insectivores.…”

Section: Evolutionary and Functional Considerationssupporting

confidence: 59%

“…In previous studies on the cerebral cortex and claustrum of the echidna [Abbie, 1940;Hassiotis et al, 2004;Ashwell et al, 2004], the olfactory tubercle of the echidna has been noted in passing, but those studies did not fully describe this region. In therian mammals, particularly those occupying a similar niche to the echidna, the olfactory tubercle is an extensive strongly laminated structure [Oswaldo-Cruz and Rocha-Miranda, 1968;Künzle and Radtke-Schuller, 2000], where olfactory information gains access to the ventral striatum [Shipley et al, 1995]. However, initial inspection of the echidna olfactory tubercle revealed that this region was remarkably underdeveloped compared to the extensive echidna piriform lobe [Hassiotis et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

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Cyto- and Chemoarchitecture of the Monotreme Olfactory Tubercle

Ashwell

2006

Brain Behav Evol

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This study was undertaken to determine whether the olfactory tubercles of two monotremes (platypus and echidna) showed cyto- or chemoarchitectural differences from the tubercles of therian mammals. Nissl staining was applied in conjunction with enzyme reactivity for NADPH diaphorase and acetylcholinesterase, and immunoreactivity for calcium binding proteins (parvalbumin, calbindin and calretinin) and tyrosine hydroxylase (echidna only). Golgi impregnations of the tubercle were also available for the echidna. The olfactory tubercle is a poorly laminated structure in the echidna, despite the pronounced development of other components of the echidna olfactory system, and the dense cell layer of the olfactory tubercle was found to be discontinuous and irregular. Granule cell clusters (islands of Calleja) were present, but were small, poorly defined and did not show the intense NADPH diaphorase activity seen in marsupial and placental mammals. A putative small island of Calleja magna was seen in only one echidna out of four. In Golgi impregnations of the echidna olfactory tubercle, the most abundant neuron type was a medium-sized densely spined neuron similar to that seen in the olfactory tubercle of some therians. Large spine-poor neurons were also seen in the polymorphic layer. In the platypus, the olfactory tubercle was very small but showed more pronounced lamination than the echidna, although no granule cell clusters were seen. In both monotremes, the development of the olfactory tubercle was poor relative to other components of the olfactory system (bulb and piriform cortex). The small olfactory tubercle region in the platypus is consistent with poor olfaction in that aquatic mammal, but the tubercle in the echidna is more like that of a microsmatic mammal than other placentals occupying a similar niche (e.g., insectivores).

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Section: Evolutionary and Functional Considerationssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Cyto- and Chemoarchitecture of the Monotreme Olfactory Tubercle

Ashwell

2006

Brain Behav Evol

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“…The material and methods used are largely the same as described in the previous papers (Radtke-Schuller and Künzle 2000; Künzle and Radtke-Schuller 2000). In short, the lesser hedgehog tenrecs (Echinops telfairi, Et), obtained from our breeding colony (Künzle 1998) were anesthetized with tribromoethanol (1.0 ml/ 100 gm, i.p.)…”

Section: Methodsmentioning

confidence: 99%

Multiarchitectonic characterization of insular, perirhinal and related regions in a basal mammal, Echinops telfairi

Künzle

Radtke‐Schuller

2000

Anatomy and Embryology

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The rhinal cortex was investigated in the Madagascan lesser hedgehog tenrec, a basal placental mammal. This region parallels the rhinal indentation and presumably contains the equivalents of the insular and perirhinal cortices. Using cyto- and myeloarchitectural, enzyme- and immunohistochemical criteria as well as data on the connections with the olfactory bulb, the rhinal cortex was subdivided tentatively along its rostrocaudal and dorsoventral planes. An area caudally adjacent to the rhinal cortex received a prominent input from the olfactory bulb and was also preliminarily characterized in this study. Because previous studies in insectivores remained controversial with regard to the identification of the claustrum, special attention was paid to the laminar organization of the rhinal cortex and its deep cell groups. The tenrec's claustrum was identified and delineated cytoarchitecturally and by its negative acetylcholinesterase stain. Latexin, a molecular marker for characterizing infragranular and claustral cells, also helped to differentiate the claustrum from the cell groups subjacent to it. Thus, the data indicate that in poorly differentiated mammals the claustrum occupies an intermediate deep position within the width of the rhinal cortex, i.e., it is separated from the subcortical white matter by additional, still unidentified, cell groups.

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“…A broadly similar laminar distribution of type I NADPH-d-reactive neurons has been noted for the Madagascan hedgehog tenrec [ Echinops telfairi , Künzle and Radtke-Schuller, 2000], some rodents [Davis, 1991;Paxinos et al, 1999] and some carnivores [Mizukawa et al, 1989].…”

Section: Cyto-and Chemoarchitecture Of the Monotreme Piriform Cortex:mentioning

confidence: 73%

“…Immunoreactivity for the calcium-binding proteins reveals distinct subclasses of neurons in therian AO and Pir [Celio, 1990;Résibois and Rogers, 1992;Frassoni et al, 1998;García-Ojeda et al, 1998;Paxinos et al, 1999;Künzle and Radtke-Schuller, 2000;Barbado et al, 2002] and was found to distinguish subregions within the echidna Pir. Immunoreactivity for TH and enzyme reactivity for NADPH diaphorase also label discrete subpopulations of neurons in the anterior olfactory nucleus and piriform cortex [Mizukawa et al, 1989;Paxinos et al, 1999;Künzle and Radtke-Schuller, 2000]. The aim of the present study was to determine what similarities and differences in cyto-and chemoarchitectural organization of these two cortical olfactory areas exist both between the echidna and the platypus and between both monotremes and therian mammals, and to try to interpret these fi ndings in evolutionary and functional contexts.…”

Section: Introductionmentioning

confidence: 99%

The Anterior Olfactory Nucleus and Piriform Cortex of the Echidna and Platypus

Ashwell¹,

Phillips²

2006

Brain Behav Evol

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The cyto- and chemoarchitecture of the anterior olfactory nucleus and piriform cortex of the short-beaked echidna and platypus were studied to determine: (1) if these areas contain chemically distinct subdivisions, and (2) if the chemoarchitecture of those cortical olfactory regions differs from therians. Nissl and myelin staining were applied in conjunction with enzyme reactivity for NADPH diaphorase and acetylcholinesterase, and immunoreactivity for calcium-binding proteins (parvalbumin, calbindin and calretinin) and tyrosine hydroxylase. Golgi impregnations were also available for the echidna. In the echidna, the anterior olfactory nucleus is negligible in extent and merges at very rostral levels with a four-layered piriform cortex. Several rostrocaudally running subregions of the echidna piriform lobe could be identified on the basis of Nissl staining and calcium-binding protein immunoreactivity. Laminar-specific differences in calcium-binding protein immunoreactivity and NADPH-d-reactive neuron distribution were also noted. Neuron types identified in echidna piriform cortex included pyramidal neurons predominating in layers II and III and non-pyramidal neurons (e.g., multipolar profusely spiny and neurogliaform cells) in deeper layers. Horizontal cells were identified in both superficial and deep layers. By contrast, the platypus had a distinct anterior olfactory nucleus and a three-layered piriform cortex with no evidence of chemically distinct subregions within the piriform cortex. Volume of the paleocortex of the echidna was comparable to prosimians of similar body weight and, in absolute volume, exceeded that for eutherian insectivores such as T. ecaudatus and E. europaeus. The piriform cortex of the echidna shows evidence of regional differentiation, which in turn suggests highly specialized olfactory function.

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The subrhinal paleocortex in the hedgehog tenrec: a multiarchitectonic characterization and an analysis of its connections with the olfactory bulb

Cited by 15 publications

References 81 publications

Cyto- and Chemoarchitecture of the Monotreme Olfactory Tubercle

Cyto- and Chemoarchitecture of the Monotreme Olfactory Tubercle

Multiarchitectonic characterization of insular, perirhinal and related regions in a basal mammal, Echinops telfairi

The Anterior Olfactory Nucleus and Piriform Cortex of the Echidna and Platypus

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