The Claustrum Is Not Missing from All Monotreme Brains

@article{Ashwell2004TheCI,
  title={The Claustrum Is Not Missing from All Monotreme Brains},
  author={Ken W.S. Ashwell and Craig D. Hardman and George Paxinos},
  journal={Brain, Behavior and Evolution},
  year={2004},
  volume={64},
  pages={223 - 241}
}
Many authors have reported that the claustrum, which comprises the insular claustrum and the endopiriform nucleus, is missing from the monotreme forebrain. We used Nissl and myelin staining in conjunction with enzyme histochemistry for acetylcholinesterase and immunohistochemistry for parvalbumin, calbindin, calretinin and tyrosine hydroxylase to examine the brains of two monotremes, the short-beaked echidna (Tachyglossus aculeatus) and the platypus (Ornithorhynchus anatinus). We found that… 
The pretectal nuclei in two monotremes: the short-beaked echidna (Tachyglossus aculeatus) and the platypus (Ornithorhynchus anatinus)
TLDR
The presence of a differentiated pretectum with similar chemoarchitecture to therians in both living monotremes lends support to the idea that the stem mammal for both prototherian and therian lineages also had a differentiated Pretectum.
Cyto- and chemoarchitecture of the amygdala of a monotreme, Tachyglossus aculeatus (the short-beaked echidna)
TLDR
Volumetric analysis indicated that the temporal amygdala in both the platypus and echidna is small compared to the same structure in both insectivores and primates, with the central and medial components of theporal amygdala being particularly small.
Chapter 2 – The Structure and Connections of the Claustrum
The claustrum is a telencephalic, pallial subcortical structure which has been identified in all eutherian and metatherian mammals. It consists of two principal subdivisions: the dorsal or insular
Development and Evolution of the Claustrum
TLDR
This embryological essay first discusses in detail the diverse historic conceptions about how the claustrum develops, pointing out both critical data obtained and faulty assumptions that led to erroneous conclusions.
Precerebellar and vestibular nuclei of the short-beaked echidna (Tachyglossus aculeatus)
TLDR
In all three precerebellar nuclear groups studied and in the vestibular nucleus organization, the cyto- and chemoarchitecture of the echidna was very similar to that seen in therian mammals and no “primitive” or “reptilian” features were evident.
The Anterior Olfactory Nucleus and Piriform Cortex of the Echidna and Platypus
TLDR
The piriform cortex of the echidna shows evidence of regional differentiation, which in turn suggests highly specialized olfactory function.
Topography and chemoarchitecture of the striatum and pallidum in a monotreme, the short-beaked echidna (Tachyglossus aculeatus)
  • K. Ashwell
  • Biology, Medicine
    Somatosensory & motor research
  • 2008
TLDR
The observations indicate that the same broad features of striatal and pallidal organization apply across all mammals and suggest that these common features may have arisen before the divergence of the monotreme and therian lineages.
Quantitative analysis of forebrain pallial morphology in monotremes and comparison with that in therians.
TLDR
It is found that the iso- and periallocortex of the platypus is relatively smooth-surfaced compared to similarly sized brains of therian mammals, with a distinct caudal shift in the positioning of cortical white matter in the forebrain, consistent with expansion of the posterior thalamic radiation.
Cyto- and Chemoarchitecture of the Monotreme Olfactory Tubercle
  • K. Ashwell
  • Medicine, Biology
    Brain, Behavior and Evolution
  • 2006
TLDR
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.
Chemoarchitecture of the Monotreme Olfactory Bulb
  • K. Ashwell
  • Medicine, Chemistry
    Brain, Behavior and Evolution
  • 2006
TLDR
The monotreme olfactory bulb of two monotremes does not show any significant chemoarchitectural dissimilarities from eutheria, despite differences in mitral/tufted cell distribution.
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References

SHOWING 1-10 OF 39 REFERENCES
Apparent Absence of Claustrum in Monotremes: Implications for Forebrain Evolution in Amniotes
TLDR
Its absence as a cytoarchitectonically discrete and identifiable structure in monotremes fails to support homology of the claustrum of therian mammals with any single part of the sauropsid pallium.
Relation of the insular claustrum to the neocortex in Insectivora.
TLDR
The claustra of 9 species of Insectivora were investigated and data strongly suggest that in the phylogenesis the insular claustrum originates from the cortex from which it gets separated by the extreme capsule.
The organization of the sensory and motor areas of cerebral cortex in the platypus (Ornithorhynchus anatinus)
TLDR
The organization of sensory and motor regions of the cerebral cortex has been studied in the platypus and a large single area of somatosensory representation in the posterior region of the hemisphere was found.
Parvalbumin and calbindin in the rat claustrum: An immunocytochemical study combined with retrograde tracing from frontoparietal cortex
TLDR
The present findings suggest that parvalbumin-immunoreactive claustral neurons may represent, at least in part, local circuit claustrals corresponding to the aspiny intrinsic neurons described in the rat claustrum in studies based on Golgi impregnation.
Afferents of the frontal cortex in the echidna (Tachyglossus aculeatus). Indication of an outstandingly large prefrontal area.
TLDR
The echidna is the only species studied to date that has a proportionally larger prefrontal cortex than humans, and it is concluded that the large anterior cortical area in this species corresponds to the prefrontal cortex of eutherian mammals.
The visual claustrum of the cat. I. Structure and connections
  • S. Levay, H. Sherk
  • Biology, Medicine
    The Journal of neuroscience : the official journal of the Society for Neuroscience
  • 1981
TLDR
The cat's dorsocaudal claustrum was studied in Golgi preparations, by electron microscopy, and by anterograde and retrograde tracer techniques, finding the claustrocortical axons terminate in all cortical layers but most heavily in layers IV and VI.
Comparative Anatomy of the Claustrum in Selected Species: A Morphometric Analysis
TLDR
The morphology of the claustrum was studied by stereological methods in representatives of five mammalian orders (Insectivora, Rodentia, Lagomorpha, Carnivora and Primates) and differences in the morphology and cellular structure may suggest differences in function of the two parts of the nucleus.
Claustrum in the hedgehog (Erinaceus europaeus) brain: Cytoarchitecture and connections with cortical and subcortical structures
TLDR
It was found that the claustrum is a well developed nucleus in the hedgehog telencephalon and, as in other mammals, is divided into dorsal and ventral parts.
The Brain of Ornithorhynchus anatinus
TLDR
This monograph, as one of the rapidly increasing number of analyses of the brains of vertebrates, may help to clarify in part the inter-relationships between the minds of lower forms and those of mammals.
Sensory receptors in monotremes.
  • U. Proske, J. Gregory, A. Iggo
  • Biology, Medicine
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 1998
TLDR
A role for the electrosensory system has not yet been established during normal foraging behaviour of the echidna, although it has been shown that it is able to detect the presence of weak electric fields in water.
...
1
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3
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