The Rat Brain in Stereotaxic Coordinates

158 Pages·1982·31.553 MB·English

by  PAXINOS (Auth.)

The Rat Brain
in Stereotaxic Coordinates
George Paxinos
School of Psychology
University of New South Wales
Charles Watson
School of Anatomy
University of New South Wales
ACADEMIC PRESS
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1982
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Printed in Australia
National Library of Australia Cataloguing-in-Publication Data
Paxinos, George, 1944-.
The rat brain in stereotaxic coordinates.
Bibliography.
ISBN 0 12 547620 5.
1. Rats — Anatomy — Atlases. 2. Brain — Atlases.
I. Watson, Charles, 1943-. II. Title.
599.32'33
Library of Congress Catalog Card Number: 81-71778
To our parents, Theodoraki and Eleni, Charles and Jeanne,
for encouraging our interest in academia, and especially to
our wives, Elly and Prue, for their tolerance and support
during the past three years.
Preface Acknowledgements
The mapping of the central nervous system is an art pioneered We are grateful to a number of scientists who took hours, even laboratory space at the Institut d'Embryologie at Nogent-sur-
by the great neuroanatomists of the nineteenth century. The days, from their busy schedules to identify structures on the Marne.
challenge of recent times has been to place such maps in an Plates and correct boundaries we had drawn. Our interaction We express our gratitude to Alan Brichta for constructing the
accurate stereotaxic reference system and to revise the deline- with them and their challenge to our preconceptions were the skull diagram.
ation of cell groups and fiber tracts in the light of the latest most rewarding experiences of this project. With pleasure we We are particularly grateful to Gordana Strumfin and Ann
findings. thank Paula Wilson (for help with the pons and medulla), Bill Topple for their excellent technical assistance in photography,
In an effort to construct an atlas of horizontal sections of the Mehler (thalamus and midbrain), Jim Fallon (amygdala, ventral drawing of the figures and construction of figure labels, and to
rat forebrain (Paxinos et al., 1980), we noticed that brain tegmental area, raphe nuclei and locus coeruleus), Richard Faull Lorraine Brooks for typing the manuscript. Our sincere thanks
sections demonstrated enhanced staining contrast and suffered (thalamus and substantia nigra), Jan Meyer (amygdala and also to the following for assisting us in important ways in the
less distortion if they were cut from an unfixed brain. We construction of abbreviations), Alan Brichta (spinal cord), production of the histological material, plates and drawings:
thought that it might be possible to obtain better delineation of 1st van Tôrk (ventral tegmental area and raphe nuclei), John Elly Paxinos, Sharon McDonald, Julia Watson, Geoff
nuclei and achieve greater stereotaxic accuracy by using fresh- Haight (neocortex, thalamus and construction of Schneider, Janelle Hopwood, Kevin Maynard and Maree Garrett.
frozen brains, especially if the brains were frozen while still in abbreviations), Konrad Talbot (delineations in AChE-stained Finally, we thank Grant Walker, Dallas Cox and James
the skull. We were also aware of the need for an atlas based on sections), Lennart Heimer, Robert Switzer and Joanna Hill Jackson of Academic Press Australia, whose skill and care
the convenient flat-skull position, suitable for adult male rats, (ventral pallidum and olfactory peduncle), Larry Swanson ensured that our work was reproduced at a standard beyond our
and which took into account the anatomical research of the last (hypothalamus and ventral tegmental area), Shirley Bayer expectations.
two decades. Such an atlas, we felt, should also represent (olfactory bulb and hippocampal formation), Steve McHanwell
sections from all regions of the central nervous system. (lumbar and sacral spinal cord), Maxwell Cowan (hippocampus
The Rat Brain in Stereotaxic Coordinates is intended for use and mammillary bodies), John Morrison (neocortex), George
by researchers and graduate students in the neurosciences. In Martin (medulla), Paul MacLean (forebrain), Sandra Laughlin
addition, senior undergraduates should find the atlas a useful (neocortex), Esmail Meisami (olfactory bulb), Dennis Steindler
adjunct to readings and lectures in brain anatomy and function. and Irena Grofova (substantia nigra), Steven Hunt (Rexed's
The photographs are of sufficient magnification to permit layers), Derek van der Kooy and Leonard Koda (medulla),
researchers to make their own judgements on the boundaries of Irving Diamond (thalamus), John Johnson (thalamus), Bill
brain structures. We would be pleased to receive any comments Armstrong (hypothalamus), Sharleen Sakai (thalamus), Fritz
on the delineations we have made so that future editions may Guldner (suprachiasmatic nucleus), Eva Bystrzycka
benefit from the experience of our colleagues. (Kôlliker-Fuse nucleus), Wilfred Schober (for making available
Although reproduction of any part of this book is subject to to us his personal copy of the Wunscher, Schober and Werner
the usual restrictions of copyright, we can assure researchers atlas), Phil Marks, Paul Herron and Mick O'Brien (for checking
that our publishers will attend promptly to any written request stereotaxic accuracy), and Piers Emson (for making available
to reproduce the figures in this atlas. However, we would like to brain sections from DFP-treated rats).
take this opportunity to stress that electrode placements and We are indebted to Professor Syd Lovibond and Professor
lesions can be represented accurately on atlas drawings only Fred Rost for making available facilities of the Schools of
after careful inspection of sections taken from the brain of the Psychology and Anatomy at the University of New South
experimental subject. Wales, and to Professor Nicole Le Douarin for providing
vii
Preface Acknowledgements
The mapping of the central nervous system is an art pioneered We are grateful to a number of scientists who took hours, even laboratory space at the Institut d'Embryologie at Nogent-sur-
by the great neuroanatomists of the nineteenth century. The days, from their busy schedules to identify structures on the Marne.
challenge of recent times has been to place such maps in an Plates and correct boundaries we had drawn. Our interaction We express our gratitude to Alan Brichta for constructing the
accurate stereotaxic reference system and to revise the deline- with them and their challenge to our preconceptions were the skull diagram.
ation of cell groups and fiber tracts in the light of the latest most rewarding experiences of this project. With pleasure we We are particularly grateful to Gordana Strumfin and Ann
findings. thank Paula Wilson (for help with the pons and medulla), Bill Topple for their excellent technical assistance in photography,
In an effort to construct an atlas of horizontal sections of the Mehler (thalamus and midbrain), Jim Fallon (amygdala, ventral drawing of the figures and construction of figure labels, and to
rat forebrain (Paxinos et al., 1980), we noticed that brain tegmental area, raphe nuclei and locus coeruleus), Richard Faull Lorraine Brooks for typing the manuscript. Our sincere thanks
sections demonstrated enhanced staining contrast and suffered (thalamus and substantia nigra), Jan Meyer (amygdala and also to the following for assisting us in important ways in the
less distortion if they were cut from an unfixed brain. We construction of abbreviations), Alan Brichta (spinal cord), production of the histological material, plates and drawings:
thought that it might be possible to obtain better delineation of 1st van Tôrk (ventral tegmental area and raphe nuclei), John Elly Paxinos, Sharon McDonald, Julia Watson, Geoff
nuclei and achieve greater stereotaxic accuracy by using fresh- Haight (neocortex, thalamus and construction of Schneider, Janelle Hopwood, Kevin Maynard and Maree Garrett.
frozen brains, especially if the brains were frozen while still in abbreviations), Konrad Talbot (delineations in AChE-stained Finally, we thank Grant Walker, Dallas Cox and James
the skull. We were also aware of the need for an atlas based on sections), Lennart Heimer, Robert Switzer and Joanna Hill Jackson of Academic Press Australia, whose skill and care
the convenient flat-skull position, suitable for adult male rats, (ventral pallidum and olfactory peduncle), Larry Swanson ensured that our work was reproduced at a standard beyond our
and which took into account the anatomical research of the last (hypothalamus and ventral tegmental area), Shirley Bayer expectations.
two decades. Such an atlas, we felt, should also represent (olfactory bulb and hippocampal formation), Steve McHanwell
sections from all regions of the central nervous system. (lumbar and sacral spinal cord), Maxwell Cowan (hippocampus
The Rat Brain in Stereotaxic Coordinates is intended for use and mammillary bodies), John Morrison (neocortex), George
by researchers and graduate students in the neurosciences. In Martin (medulla), Paul MacLean (forebrain), Sandra Laughlin
addition, senior undergraduates should find the atlas a useful (neocortex), Esmail Meisami (olfactory bulb), Dennis Steindler
adjunct to readings and lectures in brain anatomy and function. and Irena Grofova (substantia nigra), Steven Hunt (Rexed's
The photographs are of sufficient magnification to permit layers), Derek van der Kooy and Leonard Koda (medulla),
researchers to make their own judgements on the boundaries of Irving Diamond (thalamus), John Johnson (thalamus), Bill
brain structures. We would be pleased to receive any comments Armstrong (hypothalamus), Sharleen Sakai (thalamus), Fritz
on the delineations we have made so that future editions may Guldner (suprachiasmatic nucleus), Eva Bystrzycka
benefit from the experience of our colleagues. (Kôlliker-Fuse nucleus), Wilfred Schober (for making available
Although reproduction of any part of this book is subject to to us his personal copy of the Wunscher, Schober and Werner
the usual restrictions of copyright, we can assure researchers atlas), Phil Marks, Paul Herron and Mick O'Brien (for checking
that our publishers will attend promptly to any written request stereotaxic accuracy), and Piers Emson (for making available
to reproduce the figures in this atlas. However, we would like to brain sections from DFP-treated rats).
take this opportunity to stress that electrode placements and We are indebted to Professor Syd Lovibond and Professor
lesions can be represented accurately on atlas drawings only Fred Rost for making available facilities of the Schools of
after careful inspection of sections taken from the brain of the Psychology and Anatomy at the University of New South
experimental subject. Wales, and to Professor Nicole Le Douarin for providing
vii
Introduction
The main features of this atlas are: tubercle, the basolateral amygdala, the ventral thalamic nuclei).
1. It is based on the flat-skull position, and bregma, lambda, In addition, the use of this combination of stains makes possible
For a long time the rat has been widely used as a subject for or the midpoint of the interaural line can be used as a the subdivision of certain nuclei into subnuclei that correspond
research in the neurosciences. This is chiefly because of its size, reference point. to regions with particular afferent patterns or characteristic
resistance to infection and the availability of inbred strains. In 2. The atlas is based on the study of 130 adult male Wistar dendritic architecture (e.g. the subnuclei of the medial geniculate
recent years, the use of rats has increased significantly, rats (with a weight range of 270-310 g). It is suitable for nucleus, the inferior colliculus, the mediodorsal thalamic
particularly in the field of neurohistochemistry. With increasing brains of 250-350 g male rats. nucleus, the central nucleus of the amygdala). Although we
public pressure against the use of medium-sized mammals (the 3. It represents all areas of the brain and spinal cord, and often referred to a set of brain sections in which fibers were
monkey, cat and rabbit) in experimental biology, many brain areas are shown in coronal, sagittal and horizontal stained with luxol fast blue, we found the sections stained for
laboratories have opted to use only small rodents. While the planes. The brain sections shown were taken at 0.5 mm AChE of much greater value for the delineation of nuclei and
mouse is ideal for studies involving development and genetic intervals and were stained with either cresyl violet or for fiber tracts.
selection (because of its short generation time), the rat, having a the demonstration of acetylcholinesterase (AChE).
Surgery
larger brain, is more appropriate for accurate stereotaxic 4. It is based on fresh brains frozen in the skull (using deeply
localization of discrete brain areas. anaesthetized rats) in order to overcome distortion
In spite of the pre-eminent popularity of the rat for stereotaxic produced by fixation and to enhance staining contrast. Under barbiturate anaesthesia the rats were placed in a Kopf
procedures, there is no atlas of the rat brain based on the 5. Structures are delineated on the basis of data on cyto- small-animal stereotaxic instrument, and the incisor bar was
convenient flat-skull position that is sufficiently comprehensive architecture, connectivity, histochemistry and develop- adjusted until the heights of lambda and bregma skull points
and stereotaxically accurate for adult (250-350 g) male rats. In ment. were equal. This flat-skull position was achieved when the
addition, no current atlas has photographs of sufficient incisor bar was lowered 3.3 ± 0.4 mm below horizontal zero.
magnification to permit investigators to judge for themselves the Why acetylcholinesterase? Because the point of intersection of the lambdoid and sagittal
veracity of the atlas delineations. sutures is variable, we have chosen to define lambda as the
Before beginning the construction of the present atlas, we This atlas grew out of our efforts to make an atlas of horizontal midpoint of the curve of best fit along the lambdoid suture (see
surveyed the 181 articles reporting use of stereotaxic surgery in sections of the rat forebrain in stereotaxic coordinates (Paxinos skull diagram). This redefined reference point is considerably
rats which were published during 1980 in three prominent et al., 1980). We chose the acetylcholinesterase (AChE) stain for more reliable than the true lambda, and it is located 0.3 ± 0.3
neuroscience journals (Brain Research, Neuroscience Letters and that atlas for two reasons. Firstly, AChE clearly delineates many mm anterior to the interaural line. We also defined bregma as
Physiology and Behavior). We did this in order to assess current nuclei and fiber tracts whose boundaries are difficult to the point of intersection of the sagittal suture with the curve of
preferences in stereotaxic methods and nomenclature. In 52% of distinguish in Nissl-stained or Weil-stained sections. Secondly, best fit along the coronal suture. When the two sides of the
the studies surveyed, the Kônig and Klippel (1963) atlas was the use of AChE staining provides an indication of the extent of coronal suture met the sagittal suture at different points, bregma
used; in 20%, the Pellegrino and Cushman atlas was used damage to fiber systems that contain acetylcholine or the usually fell midway between the two junctions. The
(Pellegrino and Cushman 1967; Pellegrino et al., 1979); and in monoamines (Butcher and Marchand, 1978; Emson et al., anteroposterior position of bregma was 9.1 ± 0.3 mm anterior
the remainder, other atlases were used. In 79% of the studies, 1979). Furthermore, it has recently been shown that the to the coronal plane passing through the interaural line. Since
male rats were used, and the mean weight was 276 g. In 63% of distribution of AChE in certain areas is in register with the the mean anteroposterior position of bregma for the three rats
the studies^ bregma was used as the reference point; in 25%, the distribution of a number of neuropeptides (Graybiel et al., 1981). from which the photographs were taken was slightly less than
interaural line; and in 12%, lambda. In 85% of the reports, We have found that the use of AChE-stained sections 9.1 mm, 9.0 mm was used on the atlas diagrams. The top of the
English or anglicized nomenclature was used for the naming of alongside Nissl-stained sections is invaluable for the delineation skull at bregma and lambda was 10.0 ± 0.2 mm dorsal to the
brain structures. of many nuclei (e.g. the superior vestibular, the olfactory interaural zero plane. Table 1 presents mean body-weight and
Because the Kônig and Klippel atlas is by far the most widely
used atlas of the rat brain, we took note of the advantages of this
atlas in the preparation of our own. We believe that the Kônig Table 1
and Klippel atlas is popular with researchers because its Craniometric and stereotaxic data for Wistar and hooded rats
reference system closely approximates the flat-skull position and
brain structures are correctly identified in almost every case. D-V distance A-P distance
A-P distance A-P distance Interaural- Interaural- A-P distance A-P distance D-V distance
However, since the publication of Kônig and Klippel's
Interaural- Interaural- top of skull anterior part Bregma- Interaural- Interaural-
excellent atlas, knowledge of the anatomy of brain structures Weight Bregma Lambda at Bregma of Acb ac g7/7n incisor bar
has increased substantially, and the accepted parcelling of such Subject Ν (g) (mm) (mm) (mm) (mm) (mm) (mm) (mm)
regions as the thalamus, septum and amygdala has changed
significantly. In addition, some major brain areas currently 'Atlas'
studied with stereotaxic surgery (the pons, medulla and Wistar 130 290 ± 16 9.1 ± 0.3 0.3 ± 0.3 10.0 ± 0.2 11.7 0.0 -1.3 -3.3 ± 0.4
cerebellum) are not represented in the Kônig and Klippel atlas. A Coronal
further consideration is that the Kônig and Klippel atlas is based plates 1 300 9.2 0.2 10.1
on brains of 150 g female rats, whereas in 1980 more than two- Sagittal
thirds of researchers used 250-350 g male rats. This difference in plates 1 270 8.9 0.0 10.0
size and sex results in an error of over 2.0 mm in the Horizontal
plates 1 290 9.1 0.2 10.1
anteroposterior coordinate of many structures (Paxinos et al.,
1980), and many researchers have found it necessary to Hooded 10 290 ± 20 9.4 ± 0.4 0.3 ± 0.6 9.8 ± 0.2 11.9 ± 0.4 0.0 ± 0.3 -1.2 ± 0.3 -3.9 ± 0.6
determine empirically the coordinates of each structure of Juvenile
interest. Finally, the Kônig and Klippel atlas does not give the Wistar 10 180 ± 8 7.7 ± 0.4 -0.4 ± 0.3 9.9 ± 0.2 10.2 ± 0.4 -0.1 ± 0.2 -1.6 ± 0.1 -2.0 ± 0.4
position of bregma, and the drawings of brain structures do not Mature
Wistar 10 436 ± 16 9.7 ± 0.3 0.6 ± 0.3 10.7 ± 0.4 12.4 ± 0.3 -0.1 ± 0.2 -0.8 ± 0.2 -2.7 ± 0.3
match the photographs presented.
The present work represents our efforts to meet the challenge
Notes: This table should be interpreted with reference to the skull diagram. Each distance is expressed as the interval between two points or planes. Positive
of providing an atlas of sufficient accuracy, comprehensiveness distances indicate that the second member of a pair is anterior or dorsal to the first member. Negative distances indicate that the second member of a
and convenience for the needs of present-day neuroscientists. pair is posterior or ventral to the first member. A-P = anteroposterior; D-V = dorsoventral.
1
2
mean skull measurements for all rats as well as individual dipped in distilled water (H 0) and stained in 0.5% cresyl violet it was drawn in after consideration of sections obtained from de-
2
measurements for the rats from which the plate photographs for 15-30 min. They were differentiated in H 0 for 3-5 min and calcified heads. These heads were sectioned with brains in situ
2
were taken. then dehydrated through 70%, 95%, 100% and 100% alcohol. and stained with cresyl violet and luxol fast blue.
To establish the stereotaxic position of structures, reference They were then put in xylene and cover-slipped. Fiber tracts are outlined by solid lines and nuclei by dashed
needle tracks were made perpendicular to the horizontal, To make 500 ml of 0.5% cresyl violet of about pH 3.9, mix (a) lines. In general, the abbreviations are placed in the centre of
coronal and sagittal planes. For brains sectioned in the coronal 2.5 g of cresylecht violet (Chroma Gesellschaft); (b) 300 ml of structures. For the coronal and horizontal drawings, the
plane, vertical needle insertions were made at 2.0 mm intervals H 0; (c) 30 ml of 1.0 M sodium acetate (13.6 g of granular abbreviations for fiber tracts and fissures are almost always
2
through the brain (except for the penetration at 0.7 mm anterior sodium acetate in 92 ml of H 0); and (d) 170 ml of 1.0 M acetic positioned on the left hemisphere of the figure, and for nuclei
2
to the interaural line, which was chosen to avoid rupture of a acid (29 ml of glacial acetic acid added to 471 ml of H 0). Mix they are generally positioned on the right hemisphere. The
2
venous sinus). Ten such needle tracks appear on coronal plates solution for 7 days on a magnetic stirrer, then filter. ventricles are filled in with solid black.
of this atlas. Three horizontal needle insertions perpendicular to
the coronal plane were made from the posterior of the brain at
1.0, 3.0 and 5.0 mm above the interaural line and approximately AChE histochemistry Reference planes
1.0 mm lateral to the midline. The reference tracks from the
horizontal needles appear as pinholes in coronal sections. The method for the demonstration of AChE followed the Two coronal and two horizontal zero planes are given, one set
For brains sectioned in the sagittal plane, vertical needles were procedures of Koelle and Friedenwald (1949) and Lewis (1961). related to the interaural line and one to bregma. Lambda was
inserted in both hemispheres at 3.0 mm posterior to the Slides were incubated for 15 hr in the following solution: 100 ml located 0.3 ± 0.3 mm anterior to the interaural line, and it too
interaural line and at 1.0 and 2.0 mm lateral to the midline. A of stock solution to which had been added 116 mg of can be used as a reference point in conjunction with the
second pair was inserted 11 mm anterior to the interaural line at S-acetylthiocholine iodide and 3.0 mg ethopropazine (May & dorsoventral coordinate of bregma. The position of the
1.0 and 2.0 mm lateral to the midline. Horizontal needle tracks Baker). The slides were rinsed with tap water and developed for stereotaxic reference points and planes are indicated on the skull
perpendicular to the coronal plane were made at 5.0 mm and 6.0 10 min in 1% sodium sulphide (1.0 g in 100 ml of H 0) at pH diagram. The stereotaxic reference grid shows 0.5 mm intervals.
2
mm dorsal to the interaural line and 2.0 mm lateral to the 7.5. They were then rinsed with water and immersed in 4% Stereotaxic coordinates can be readily obtained by using a
midline. Horizontal needle tracks perpendicular to the sagittal paraformaldehyde in phosphate buffer for 8 hr, and then transparent ruler or by superimposing a transparent grid over
plane were made at 5.0 mm dorsal to the interaural line and 2.0 allowed to dry. Subsequently, they were dehydrated for 5 min in the drawing.
mm and 8.0 mm anterior to it. 100% alcohol, then immersed in xylene and cover-slipped with
For brains sectioned in the horizontal plane, two vertical Permount.
reference tracks were made by inserting a needle at 2.0 and 9.0 The stock solution was a 50 mM sodium acetate buffer at pH Coronal drawings
mm anterior to the interaural line and approximately 1.4 mm 5.0 which was made 4.0 mM with respect to copper sulphate and
lateral to the midline. These reference tracks appear as pinholes 16 mM with respect to glycine. (This was done by adding 6.8 g of The large number at the bottom left of each drawing shows the
in the horizontal sections. Five horizontal needle tracks sodium acetate, 1.0 g of copper sulphate crystals and 1.2 g of anteroposterior distance of the corresponding plate from the
perpendicular to the coronal plane were made by inserting glycine to 1.0 liter of H 0 and lowering the pH to 5.0 with HC1.) vertical plane passing through the interaural line. The large
2
needles at 1.0, 3.0, 5.0, 7.0 and 8.0 mm above the interaural line. It was noticed that fresh, unfixed tissue showed a substantially number at bottom right shows the anteroposterior distance of
stronger reaction for both stains than tissue fixed with formalin, the plate from bregma. The numbers on the left margin show the
paraformaldehyde, glutaraldehyde or alcohol. (A detailed dorsoventral distance from the horizontal plane passing through
Histology protocol of the staining procedures may be obtained from the the interaural line. The numbers on the right margin show the
authors). dorsoventral distance from the horizontal plane passing through
After surgery all rats were decapitated, and their brains were bregma and lambda on the surface of the skull. The numbers on
frozen on dry ice or C0 within 3 min of decapitation. Brains the top and bottom margins show the distance of structures
2
that were sectioned coronally were blocked at 3.0 mm anterior to Photography from the midline.
the interaural line prior to freezing. Brains removed from the
skull for sectioning on the horizontal or sagittal planes initially Photographs of stained brain sections were taken with a Nikon
presented a problem in that they assumed the shape of the stage Multiphot macrophotographic apparatus on 4" χ 5" Kodak Sagittal drawings
on which they were positioned. To avoid this distortion, the Plus X film. High contrast (grade 4) Ilfospeed paper was used
brains were frozen in the skull, and the skull bones were then for the Nissl sections, whereas lower contrast (grade 2) paper The large number at the bottom left of each drawing shows the
prized off the frozen brains. was used for the AChE sections. For sections in which the AChE distance of the corresponding plate from the midline. The
Spinal cord segments were obtained from 9 rats and were activity in the cerebellum and the cerebral cortex was too weak numbers on the left margin show the dorsoventral distance from
fresh frozen in propane cooled with liquid nitrogen. Representa- to be clearly seen, the printing time was increased and the non- the horizontal plane passing through the interaural line. The
tive sections from the major regions of the spinal cord are cortical areas were dodged. Even after such artificial enhance- numbers on the right margin show the dorsoventral distance
included in the atlas. ment, these areas still display the weakest AChE reactivity in the from the horizontal plane passing through bregma and lambda
Frozen brains were sectioned on an American Optical Cryocut photographs in which they appear. on the surface of the skull. The numbers on the bottom margin
at 40 μηι. Sections were obtained parallel to the stereotaxic The photographs were reproduced at Macarthur Press, show the anteroposterior distance from the coronal plane
planes by adjusting the angle of cutting until the needle tracks Sydney, on a Hell Computer scanner equipped with a laser light, passing through the interaural line. The numbers on the top
encountered were parallel (as far as was possible) to the plane of enabling an accurate halftone reproduction of 150 line screen margin show the anteroposterior distance from the coronal
section. Sections were taken directly from the cryotome knife on whilst reducing the need to deep etch the unnecessary back- plane passing through bregma.
uncoated slides with the help of an anti-roll device. ground.
Three sections at successive 0.5 mm intervals were stained
Horizontal drawings
alternately with cresyl violet or for the demonstration of AChE.
Staining was carried out on the same day as cutting, according to Drawings
the following procedures. The large number at the bottom left of each drawing shows the
It was thought that the drawings would be more informative if dorsoventral distance of the corresponding plate from the
they were not stylized, and for this reason artistic licence was horizontal plane passing through the interaural line. The large
Cresyl violet rarely taken. There was no mirror-image drawing and, with the number at top right shows the dorsoventral distance of the plate
exception of small adjustments to distorted midlines and cortex, from the horizontal plane passing through bregma and lambda
Slides were immersed for 5 min in each of the following: xylene, the drawings depict the asymmetries present in the sections. on the surface of the skull. The numbers on the bottom margin
xylene, 100% alcohol, 100%, 95% and 70% alcohol. They were When part of an atlas section was missing or severely distorted, show the anteroposterior distance from the coronal plane
passing through the interaural line. The numbers on the top line and lambda; the dorsoventral distance between the posterior to the interaural line in the juvenile rats and 0.6 mm
margin show the anteroposterior distance from the coronal interaural line and the surface of the skull at bregma; and the anterior to this line in the mature rats (0.3 mm anterior in the
plane passing through bregma. The numbers on the left and location of certain brain structures (anterior part of accumbens 'atlas' rats). Unexpectedly, the dorsoventral distance between
right margins show the distance of structures from the midline. nucleus, anterior commissure, genu of the facial nerve) relative the interaural line and bregma for the juvenile rats (9.9 mm) was
Values ventral to the interaurai horizontal zero or posterior to to these reference points. It is evident, therefore, that this atlas almost the same as that of the 'atlas' rats (10.0 mm). In the
either the interaural line or bregma are preceded by a minus sign. can be used with male hooded rats of 250-350 g weight. (Table 1 mature rats, the interaural line to bregma vertical distance was
should be interpreted with reference to the skull diagram.) 10.7 mm.
Table 1 shows that some of the skull measurements for In hooded rats, as well as in juvenile (180 g), mature (436 g)
An example
juvenile (180 g) and mature (436 g) male Wistar rats differ and 'atlas' (290 g) Wistar rats, bregma was found to be almost
substantially from the values obtained for the rats on which this exactly at the centre of the crossing of the anterior commissure
If it is desired to insert an electrode into the basolateral amyg- atlas is based. The anteroposterior distance between the (at the point at which the posterior limbs are continuous with the
daloid nucleus, Fig. 20 reveals the coordinates with reference to interaural line and bregma is 7.7 mm in the juvenile and 9.7 mm midline segment of the commissure). These data confirm the
the interaural line to be 6.2 mm anterior to the interaural line, in the mature rats (9.0 mm in 'atlas' rats). Lambda is 0.4 mm observation of Whishaw et al. (1977) that bregma is more stable
1.5 mm dorsal to it, and 5.0 mm lateral to the midline. The
coordinates of the same structure obtained with reference to
bregma are 2.8 mm posterior to bregma, 8.5 mm ventral to it,
and 5.0 mm lateral to the midline.
Stereotaxic accuracy
Consideration of the actual coordinates of some structures
reveals that the variability of values obtained from the three
planes is well within the range of values expected from the use of
three different rats. For example, the coordinates given by the
three planes for the bed nucleus of the anterior commissure and
the trochlear nucleus are similar (see Table 2). However, some
structures located far from the stereotaxic reference points may
have coordinates in the three planes differing by as much as 0.5
mm. The positioning of structures on the diagrams was not
adjusted to make the three brains conform, because such
adjustments would have removed the correspondence between
photograph and diagram.
Table 2
Coordinates of the bed nucleus of the anterior commissure and the trochlear
nucleus obtained from the three planes
Bed nucleus of the ant comm Trochlear nucleus
Plane A-P D-V Lat A-P D-V Lat
Coronal 8.2 3.4 0.9 1.7 3.4 0.4
Sagittal 8.0 3.4 0.9 1.8 3.5 0.4
Horizontal 8.1 3.4 0.9 1.8 3.4 0.4
Medium-sized (270-310 g) male rats were used in the
construction of this atlas. As a result the structures are further
apart from each other than in the Kônig and Klippel atlas, which
is based on small (150 g ) female rats. Due to the difference in
size and sex, up to 2 mm differences in the location of structures
will be found if the two atlases are compared.
Atlases are frequently used for work with animals of different
strains and weights than those for which the atlases were
intended. We have attempted to estimate the error that will
occur if this atlas is used with male hooded (Long Evans) rats of
Skull diagram
the weight (290 g) used in the atlas, as well as with juvenile (180
Dorsal and lateral views of the skull of a 290 g male Wistar rat. The positions of
g) and mature (436 g) male Wistar rats. Table 1 shows that the bregma, lambda and the plane of the interaural line are shown above the lateral
craniometric data and location of key brain structures in the view. The distance between the horizontal plane passing through bregma and
hooded rats of 290 g weight are very similar to those of the 290 g lambda and the horizontal plane passing through the interaural line is shown on
Wistar rats on which this atlas is based. Thus, in the two strains, the right of the lateral view. The distance between the incisor bar and the
horizontal plane passing through the interaural line is shown on the left of the
the following distances are the same, or within 0.3 mm of each
lateral view. Lambda (midpoint of the curve of best fit along the lambdoid
other: the anteroposterior distance between the interaural line
suture) is 0.3 mm anterior to the coronal plane passing through the interaural
and bregma; the anteroposterior distance between the interaural line.
3
4
than the interaural line for positioning of electrodes in brain Table 3
Delineation of certain regions in the central nervous system of the rat
structures close to, or anterior to, bregma. However, data from
insertion of needles aimed at the level where the facial nerve
Structure References Comments
leaves the facial genu (Fig. 35) show that the interaural reference
point is more stable than bregma for localization of such
Neocortex Zilles et al., 1980 No boundaries are indicated but AChE staining patterns in the parietal, cingulate, retrosplenial,
posterior structures. Therefore, if juvenile or mature rats are
Haight & Neylon, 1978 and visual areas 17, 18 and 18a should provide readers with an indication of the likely extent of the
used, greater accuracy can be achieved if bregma is used as the
areas identified.
reference point for work with rostral structures and the
interaural line for work with caudal structures. A further Olfactory bulb and Haberly & Price, 1978
improvement in accuracy can be obtained by taking into account peduncle De Olmos et al., 1978
the actual location of the accumbens nucleus (anterior part of
Acb shown on Fig. 9) and the genu of the facial nerve (Fig. 35). Islands of Calleja Fallon et al., 1978
In agreement with Slotnick and Brown (1981), we noticed that
Ventral pallidum, Heimer & van Hoesen, 1979
coordinates of structures (in rats within the size range for which
substantia innominata, Switzer et al., in press
the atlas was constructed) were closer to target if the coordinates
nuclei of the diagonal
given by the interaural and bregma reference systems were band
averaged.
Septum Swanson & Cowan, 1979 We recognize a septohypothalamic nucleus (Bleier et al., 1979) of medium AChE staining
In this atlas, minor discrepancies exist between the co-
intensity, which differentiates this nucleus from the poorly stained ventral part of the lateral
ordinates obtained for a single structure from the three planes
septum and from the medial part of the bed nucleus of the stria terminalis. A large region of dense
represented. These discrepancies result from (a) individual AChE staining anterolateral to the medial septal nucleus does not correspond to any of the named
differences between the rats used; (b) deviation or drifts of septal nuclei but seems to occupy a space between nuclei.
needles during insertion (especially needles penetrating
Amygdala Kretteck & Price, 1978 The basolateral nucleus is the most AChE-reactive nucleus of the amygdala. We separately
horizontally for 30 mm into the brain); (c) distortion caused by
De Olmos, 1972 identified a ventral part of the basolateral nucleus which shows little AChE reactivity. This region
freezing; (d) sectioning on a plane not perfectly parallel or
contains large cells similar to those of the basolateral nucleus and has been considered as belonging
normal to the inserted needles; (e) distortion caused in mounting to it by a number of investigators. The cortex-amygdala transition zone and the amygdalo-
the sections on the slides, and (f) constraints imposed by the hippocampal area could be readily distinguished in most of their extent by their dense AChE
need to obtain sections at intervals of exactly 0.5 mm. In the reactivity. The lateral subdivision of the central nucleus is less reactive than its medial subdivision.
Immunoreactivity for a number of peptides (enkephalin, vasoactive intestinal polypeptide and
coronal plates, an additional error resulted from the fact that
cholecystokinin) has been shown to be restricted to the AChE-poor segment of the central nucleus
Plates 1-3, 26 and 38-42 were taken from rat brains different
(Marley et al., 1981; Paxinos, in press).
from the one seen in the remaining coronal plates. This sup-
plementation was necessary because of distortion of the Hippocampal Blackstad, 1956 The CA2 field displays unmistakably dense AChE staining and corresponds with the area reported
:
olfactory bulbs and caudal medulla in the brain from which formation Swanson & Cowan, 1977 to contain AChE positive cells by Talbot and Butcher (1976).
Bayer, 1980
most of the plates were taken and because of the loss of one
section at the level at which the brain was blocked.
Thalamus Herkenham, 1979 The intralaminar complex (central medial, paracentral and centrolateral nuclei), as well as the
Faull & Carman, 1978 anteroventral nucleus, rhomboid nucleus and lateral part of the mediodorsal nucleus, shows high
Mehler, 1969 AChE reactivity and defines boundaries that would have been difficult to delineate in Nissl-stained
Nomenclature Jones & Leavitt, 1974 material. The ventral posteromedial nucleus shows very little reactivity and can be distinguished
Morest, 1964 readily from the more reactive ventral posterolateral nucleus, ventromedial nucleus and posterior
group nuclei. The parvocellular part of the ventral posterior nucleus displays staining similar to
After our review of the literature revealed that English
that of the ventral posteromedial nucleus. The ventral lateral geniculate nucleus displays more
nomenclature is currently used in about 85% of neuroscience staining in its magnocellular (lateral) part than in its parvocellular (medial) part. In the medial
articles, we decided to use English rather than Latin terms. geniculate, the distribution of AChE corresponds well to the subdivisions proposed by Morest
Retention of rarely used Latin terms and the construction of (1964) in the cat, with the medial nucleus showing the highest reactivity.
latinized terms for newly named nuclei would, we believe, have
Ventral tegmental area Phillipson, 1979 The interfascicular, paranigral and parabrachial pigmented nuclei are reactive for AChE. The
been an unprofitable exercise. It would also have delayed the
medial terminal nucleus of the accessory optic tract is almost completely devoid of AChE
development of a standardized list of terms and abbreviations to
reactivity and thus is clearly separated from the surrounding, densely reactive, compact part of the
which atlases should contribute. However, some Latin terms substantia nigra.
that are strongly entrenched, such as 'stria terminalis', have
been retained and not translated into artificial anglicized forms. Interpeduncular nucleus Berman, 1968 The central and paramedian subnuclei were found to display some of the highest AChE reactivity
in the brain.
Abbreviations Pretectal nuclei Scalia, 1972 The olivary pretectal and anterior pretectal nuclei display intense AChE reactivity.
Superior colliculus The intermediate grey layer was distinguished from the equally reactive intermediate white layer by
The abbreviations used to label the drawings were constructed so the appearance of clusters of AChE in the latter. The intermediate white layer was seen to contain
as to give a strong clue to the identity of the structures they large cells in Nissl-stained sections as well as in Kluver-Berrara preparations.
represent. After considering the main features of the abbrevi-
Inferior colliculus Rockel & Jones, 1973 The AChE-poor dorsomedial part of the central nucleus of the inferior colliculus can be
ations used by the St. Louis group (e.g. Saper and Loewy, 1980),
Ryugo & Killackey, 1975 distinguished from the more reactive ventrolateral part. In turn, the ventrolateral part can be
Oswaldo-Cruz and Rocha-Miranda (1968) and other authors, we distinguished from the external nucleus because of the clustered pattern of staining in the latter.
adopted the following guidelines for the construction of our
abbreviations. Central grey Mantyh 1982 A dorsal part poorly stained for AChE and a medial, well-stained part have been delineated on
Beitz, 1982 those plates in which the subdivisions were optimally displayed.
The abbreviations represent the order of words as spoken in
English (e.g. DLG = dorsal lateral geniculate nucleus). Capital
Raphe nuclei Johansson et ai, 1981 The median raphe shows intense AChE staining, while the raphe pallidus shows poor staining.
letters represent nuclei, and lower-case letters represent fiber Parent et al., 1981
tracts. Thus the letter 'N' has not been used to denote nuclei, Steinbusch, 1981
and the letter 't' has not been used to denote fiber tracts. The Table 3—continued
general principles used in the abbreviations of the names of
Nuclei of the trapeziod The lateral nucleus of the trapezoid body displays intense AChE reactivity and can be easily
elements in the periodic table were followed as closely as
body distinguished from the poorly reactive medial nucleus of the trapezoid body and superior olive.
possible—the capital letter representing the first letter of a word
in a nucleus is followed by the lower case letter most Trigeminal nuclei Watson & Switzer, 1978 The principal sensory nucleus of the trigeminal nerve contains a dorsomedial part poorly stained
characteristic of that word (not necessarily the second letter: e.g. for AChE and a ventrolateral part of medium staining. This subdivision is not indicated on the
Mg = magnesium; Rt = reticular thalamic nucleus). Com- figures because we did not find a report supporting such a division on other grounds.
pound names of nuclei have a capital letter for each part (e.g.
Locus coeruleus The densely AChE-stained locus coeruleus can be easily distinguished from the poorly stained
MD = mediodorsal thalamic nucleus). If a word occurs in the
ventral parabrachial nucleus.
names of a number of structures, it is usually given the same
abbreviation (e.g. reticular thalamic nucleus = Rt; reticuloteg- Facial nucleus Watson et al., 1982 The motor nuclei of the cranial nerves contain intense AChE reactivity which extends beyond the
mental nucleus of the pons = RtTg). Exceptions to this rule are nuclear boundaries as defined by distribution of cell bodies. This spread is probably due to the
presence of the enzyme in dendrites. In the case of motor nuclei, as well as in some other instances
made for well-established abbreviations such as VTA. Abbrevi-
where AChE seemed to spread beyond the conventionally (Nissl) defined boundaries (e.g. motor
ations of brain regions are omitted where the identity of the
nucleus of the trigeminal nerve, oculomotor nucleus, basolateral amygdaloid nucleus, olfactory
region in question is clear from its position (e.g. Arc = arcuate tubercle), the boundaries of the nuclei were drawn on the basis of adjacent sections stained with
hypothalamic nucleus, not ArcH). Arabic numerals are used cresyl violet.
instead of Roman numerals in identifying (a) cranial nerves and
nuclei (as in the Berman, 1968, atlas), (b) cortical layers, (c) Paragigantocellular Andrezik et al., 1981
reticular nucleus
cerebellar folia, and (d) layers of the spinal cord. While the
spoken meaning is the same, the detection threshold is lower and Lateral reticular nucleus Wùnscher et al., 1965 The reactive part of the lateral reticular nucleus is restricted to its external parvocellular division.
ambiguity is reduced.
Spinal cord Rexed, 1952, 1954 In the spinal cord, the identification of the level of the plates was made by comparison with a set of
Sidman et al., 1971 sections obtained from a rat in which the segments were identified from the roots. Therefore the
The basis of delineation of structures Steiner & Turner, 1972 levels indicated are approximate (± 1 segment). Comparison of the sections of the rat spinal cord
McHanwelI & Biscoe, 1981 presented here with those of the mouse presented in the Sidman et ai. atlas and in McHanwell and
Biscoe's report reveals that the lumbar enlargement occurs more caudally in the rat than in the
Nuclear and fiber-tract boundaries were determined after mouse.
consideration of authoritative studies published on the
cytoarchitecture, connectivity, histochemistry and development
of the central nervous system (see Table 3). Inconsistencies in
demarcation found in the literature were usually resolved in
favour of the delineation supported by the AChE-distribution in
our material. In many cases, assistance with the construction of
boundaries was provided by a number of colleagues who have
special knowledge of the anatomy of particular brain regions
(see Acknowledgements). We also benefited from our
examination of the delineation of structures in a number of rat,
mouse and cat brain atlases (Berman, 1968; Mitro and
Palkovits, 1981; Palkovits and Jacobowits, 1974; Pellegrino et
al., 1979; Sidman et al., 1971; Wùnscher et al., 1965). Our
greatest debt is to the rat brain atlas of Kônig and Klippel (1963).
5