Transcript Brain Cytoarchitecture Poster

Brain Cytoarchitecture in a Large Grazing Marsupial, Rufous Wallaby Thylogale billardieri.
Cindy D. Knaff, under the direction of Dr. John I. Johnson, Radiology
RUFOUS WALLABY
OLFACTORY
DOMESTIC SHEEP
SYSTEM
Thylogale billardieri
Ovis aries
turs
Results
Visible lamination in cell groups within the brain is one indicator of
relatively well developed systems. Sections from both species show
several visibly laminated brain regions subserving olfaction, vision, and
audition, as well as a large extent of laminated cerebral isocortex.
The OLFACTORY BULBS in both species are large and show a high degree
of visible lamination.
From
http://brainmuseum.org/Specimens/marsupalia/
rufwallaby/index.html
Original photograph, John I. Johnson
ABOVE: Coronal view of the olfactory bulb and stalk..
ABOVE: Coronal view of the olfactory bulb and stalk.
The VISUAL SUPERIOR COLLICULI are larger than the AUDITORY
INFERIOR COLLICULI in both species, and show visible lamination. This
is typical of herbivorous “prey species” who must keep a watch for predators
while still far away.
VISUAL
AND
AUDITORY
SYSTEMS
ABOVE: Sagittal view of the superior and inferior colliculi.
ABOVE: Sagittal view of the superior and inferior colliculi.
VISUAL
SYSTEM
The VISUAL LATERAL GENICULATE NUCLEUS shows visible
lamination in both species. Sheep have three distinct laminae in each
lateral geniculate nucleus (Clarke, et al., 1988), while Rufous Wallabies
have 7 or 8 laminae (Sanderson et al., 1984, 1987), some of which are
visible here.
kog
ABOVE: Six standard views of the intact brains.
From http://brainmuseum.org/Specimens/marsupalia/rufwallaby/index.html
From http://brainmuseum.org/Specimens/artiodactyla/sheep/index.html
The AUDITORY DORSAL COCHLEAR NUCLEUS shows distinct
lamination in both species. This nucleus has recently been shown to
have a cerebellum-like function (Oertel & Young, 2004).
Introduction
Brain evolution can be seen through comparative neurology. Wallabies, large grazing
marsupials, provide opportunities to study evolutionary convergences with brains of
independently evolved brains of large grazing placental mammals, from a separate branch of
mammalian radiation. We have analyzed the internal structure of the brains of Rufous
Wallabies Thylogale billardieri, in direct comparison with their counterpart structures in
Domestic Sheep Ovis aries.
ABOVE: Sagittal view of the lateral geniculate nucleus and optic tract.
ABOVE: Sagittal view of the lateral geniculate nucleus and optic tract
AUDITORY
SYSTEM
Conclusions
These particular parallel hyperdevelopments in maximally
distant related species appear to be related to environmental
adaptations rather than to phylogenetic relationships.
Procedures
Sections of brains from museum collections were examined for evidence of specializations
related to herbivorous grazing behavior. These wallaby and sheep brains were dehydrated,
embedded in nitrocellulose (celloidin), sectioned at 35 um intervals and were stained with
thionine, a standard Nissl staining procedure, to show distributions of neuronal cell bodies..
REFERENCES
Clark PG, Martin KA, Rao Vm, Whitteridge D. The dorsal lateral geniculate nucleus of the sheep and its
retinal connections. Q J Exp Physiol. 1988 May:73(3):295-304.
Oertel D. Young ED, What’s a cerebellar circuit doing in the auditory system? Trends Neurosci. 2004
Feb:27(2):104-10.
ABOVE: Horizontal view of the dorsal and ventral cochlear nuclei.
ABOVE: Horizontal view of the dorsal and ventral cochlear nuclei.
Sanderson KJ, Haight JR, Pettigrew JD. The dorsal lateral geniculate nucleus of macropodid marsupials:
cytoarchitecture and retinal projections. J Comp Neurol. 1984 Mar 20:224(1):85-106.
Sanderson KJ, Nelson JE, Crewther DP, Crewther SG, Hammond VE. Retinogeniculate patterns in
diprotodont marsupials. Brain Behav Evol. 1987:30(1-2):22-42
See the atlases of the brains of dolphins, sheep, humans and axolotls at
http://www.brains.rad.msu.edu, http://brainmuseum.org or http://www.
user/brains/atlases msu.edu A similar atlas of the brains of rufous
wallabies is in preparation for these sites.
Poster design, adviser and printer
Gearl Diggs, Radiology Dept.
Michigan State University
Supported by The Division of Integrative Biology and Neuroscience
of THE NATIONAL SCIENCE FOUNDATION
grants IBN 0131267, 0131028, 0131826.