SOMAESTHETIC PATHWAYS IN THE MARSUPIAL PHALANGER, TRICHOSURUS VULPECULA

Dennis, Barbara J.; Kerr, Donald

doi:10.1038/icb.1961.4

Cited by 11 publications

(2 citation statements)

References 3 publications

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“…Also, in the three genera of marsupials studied, Didelphis, Trichosurus and Macropus, the subparafascicular nucleus is lo cated in close proximity to the medial geniculate nu cleus, whereas in cats [Berman and Jones, 1982] it is just ventral to the parafascicular nucleus. In possums, Dennis and Kerr [1961] designated this region the parageniculate nucleus, as it was found to receive path ways from the anterolateral column.…”

Section: Caudal Intralaminar Nucleimentioning

confidence: 99%

A Cyto-Architectonic Description of the Thalamus of the Tammar Wallaby, Macropus eugenii

Mayner

1989

Brain Behav Evol

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Very few studies are available on the cyto-architectural features of the thalamus of metatherian mammals. Most of these studies describe the thalamus of a polyprotodont metatherian, the North American opossum, Didelphis virginiana. Studies on diprotodont metatherians are fewer still. There are two descriptions of the thalamus of the Australian possum Trichosurus vulpecula. The only part of the thalamus that has been described in the wallabies is the lateral geniculate nucleus. Hence, there was a need for a description of the thalamus in a wallaby. This study describes the organisation and the cyto-architectonics of the thalamus of the tammar, Macropus eugenii. Except for the midline nuclei, the boundaries of all other nuclei are well demarcated due to their well-differentiated nuclear components. Within the lateral posterior complex, a pulvinar nucleus was identified, and the pre-tectal nuclei show extensive differentiation, as do the medial geniculate nuclei. Also, a small centre-median nucleus was identified. The anteroventral nucleus retains its dorsal position for its entire rostrocaudal extent. The nucleus of the optic tract is located in a dorsal position in the tammar, as it is in cats. The general conclusion from this study is that the nuclear organisation of the thalamus in the tammar, a metatherian mammal, is complex and comparable in most respects to that in cats, eutherian mammals.

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Section: Caudal Intralaminar Nucleimentioning

confidence: 99%

A Cyto-Architectonic Description of the Thalamus of the Tammar Wallaby, Macropus eugenii

Mayner

1989

Brain Behav Evol

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“…It possesses very strong limb (especially forelimb) musculature and displays reasonable but not facile dexterity in manipulation of objects with the forepaws (see Ride, 1970, for more details). Although few studies of somatosensory pathways in this or other Australasian marsupials have been published, Clezy et al (1961) and Dennis and Kerr (1961) have demonstrated the presence of major classical pathways (dorsal column-medial lemniscus and anterolateral systems) in the brainstem in Trichosurus. The forebrain components of these pathways that relate thalamus and cortex in this species have also been studied by Rockel et al (1972) and Haight and Neylon (1978); and, at least in general outline, they resemble the placental arrangement.…”

Section: Discussionmentioning

confidence: 97%

Projection of cervical dorsal root fibers to the medulla oblongata in the brush‐tailed possum, Trichosurus vulpecula

Culberson

1987

Am. J. Anat.

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This study describes the projection of cervical spinal afferent nerve fibers to the medulla in the brush-tailed possum, a marsupial mammal. After single dorsal roots (between C2 and T1) were cut in a series of animals, the Fink-Heimer method was used to demonstrate the projection fields of fibers entering the CNS via specific dorsal roots. In the high cervical spinal cord, afferent fibers from each dorsal root form a discrete layer in the dorsal funiculus. The flattened laminae from upper cervical levels are lateral and those from lower cervical levels are medial within the dorsal columns. All afferent fibers at this level are separated from gray matter by the corticospinal fibers in the dorsal funiculus. All cervical roots project throughout most of the length of the well-developed main cuneate nucleus in a loosely segmentotopic fashion. Fibers from rostral roots enter more lateral parts of the nucleus, and fibers from lower levels pass to more medial areas; but terminal projection fields are typically large and overlap extensively. At more rostral medullary levels, fibers from all cervical dorsal roots also reach the external cuneate nucleus. The spatial arrangement here is more complex and more extensively overlapped than in the cuneate nucleus. Rostral cervical root fibers reach ventral and ventrolateral areas of the external cuneate nucleus and continue to its rostral pole; more caudal root fibers project to more dorsal and medial regions within the nucleus. These results demonstrate that projection patterns of spinal afferents in this marsupial are similar to those seen in the few placental species for which detailed data concerning this system are available.

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Afferent connections to the diencephalon in the marsupial phalanger and the question of sensory convergence in the “Posterior Group” of the thalamus

Röckel

Heath

Jones

1972

J of Comparative Neurology

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the marsupial with a view toThe various afferent pathways terminating in the thalamus of phalanger have been investigated with the Nauta techniques, determining the extent of overlap and convergence of these pathways. If this had proved to be extensive, it would have lent support to the views of some authors that, in primitive and generalized mammals, the relay nuclei are in the process of differentiating out of a single archetypical, multi-modal nucleus.However, the amount of overlap between the various afferent pathways in this animal is no greater than in the cat and monkey; in the case of the ventral nuclear complex, despite the presence of a common sensory and motor cortical representation, the overlap between the somatic sensory and cerebellar pathways is probably less than in the higher mammals. The question, therefore, arises as to whether differentiation of certain thalamic nuclei may precede that of the cortical area with which they are connected.The results furnish evidence for the homologies of the posterior group of thalamic nuclei in other mammals, but the limited amount of overlap of afferent pathways occurring in the posterior group is not necessarily indicative of its being the common precursor of all the sensory relay nuclei.

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SOMAESTHETIC PATHWAYS IN THE MARSUPIAL PHALANGER, TRICHOSURUS VULPECULA

Cited by 11 publications

References 3 publications

A Cyto-Architectonic Description of the Thalamus of the Tammar Wallaby, <i>Macropus eugenii</i>

A Cyto-Architectonic Description of the Thalamus of the Tammar Wallaby, <i>Macropus eugenii</i>

Projection of cervical dorsal root fibers to the medulla oblongata in the brush‐tailed possum, Trichosurus vulpecula

Afferent connections to the diencephalon in the marsupial phalanger and the question of sensory convergence in the “Posterior Group” of the thalamus

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