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Folia Primatologica | 1981

New and Revised Data on Volumes of Brain Structures in Insectivores and Primates

Heinz Stephan; Heiko D. Frahm; Georg Baron

More than 2,000 data on volumetric measurements of 42 structures in a variety of up to 76 species (28 insectivores, 21 prosimians, 27 simians) are given. All volumes measured in serial sections were converted to fresh volumes of a brain having a standard size within a given species. The date are available to all scientists for comparison and analysis. To allow critical evaluation, details on fixation and preparation, on determination of fresh brain weights and volumes of brain parts and on intraspecific variability are given.


Folia Primatologica | 1985

Volume comparisons in the cerebellar complex of primates. II: Cerebellar nuclei

Shozo Matano; Georg Baron; Heinz Stephan; Heiko D. Frahm

Volumes of medial, interposed, and lateral cerebellar nuclei (MCN, ICN, and LCN) were measured in Insectivora, Scandentia, and Primates, including man. The relative size of the nuclei was expressed in size indices. Insectivora had by far the smallest cerebellar nuclei. The simians, in general, had larger cerebellar nuclei than the prosimians, but there was considerable overlap. From Insectivora to man, the MCN was the least progressive and the LCN the most progressive. The indices are expected to reflect the relative size of the three longitudinal zones of the cerebellum (vermis/MCN, pars intermedius/ICN, hemisphere/LCN). They, together with those of the ventral pons and cerebellum (part I), are discussed in relation to the predominant locomotor pattern of a species, and with reference to evolutionary trends in primate phylogeny.


Brain Behavior and Evolution | 1974

Differential Phylogenetic Development of the Acoustic Nuclei among Chiroptera; pp. 7–23

Georg Baron

The volumes of the acoustic nuclei of 19 speciesof Chiroptera belonging to 8 families have been compared with those of the basal insectivores by aid of the allometry formula. The progression indices h


Evolution | 1980

BRAIN STRUCTURE IN CHIROPTERA: SOME MULTIVARIATE TRENDS

Georg Baron; Pierre Jolicoeur

Previous studies have shown considerable variation among Chiroptera with respect to the size of the whole brain (Pirlot and Stephan, 1970; Stephan, 1977; Eisenberg and Wilson, 1978), of its major regions (Stephan and Pirlot, 1970; Stephan, Pirlot and Schneider, 1974; Pirlot and Pottier, 1977) and of several sensory and motor nuclei (Baron, 1969, 1970a, 1970b, 1974, 1977a, 1977b, 1978). An interesting relationship has emerged between the size of the brain or of its major regions and eco-ethological adaptations. Since an animals interactions with its environment are controlled largely by the nervous system, quantitative brain structure could be expected to reflect major evolutionary trends. Sensory nuclei should relate particularly well to environmental adaptations, for sensory stimuli are important both for the elicitation of behavior and for its organization in space and time. The present paper is an attempt to provide, using multivariate statistical methods, an integrated quantitative description of detailed differences in brain structure between Chiroptera and primitive Insectivora as well as among Chiroptera themselves. Our analysis is based on Barons extensive series of data on the volumetric development of eighteen nuclei and brain centers (references just given). Data from Stephan and Pirlot (1970) on body size and on the volume of the olfactory bulb are also used. Five functional systems are represented in the present data: four informational channels through which environmental energetic fields are sensed (chemical [olfactory], electromagnetic [visual] , mechanical [acoustic] and kinetic [vestibular]), plus the cerebellar nuclei (effectory system), which, because of their input-output relations, may be considered important as centers of sensori-motor inRevised September 28, 1979


Brain Behavior and Evolution | 1980

Brain Center Correlations among Chiroptera

Pierre Jolicoeur; Georg Baron

Correlations between progression indices of five categories of nuclei and brain centers indicate that Megachiroptera rely primarily on vision and olfaction while Microchiroptera rely primarily on audition. Among Microchiroptera, some rely more heavily on olfaction than on vision as a secondary sense, and vice-versa. There may have been compensatory effects, in the course of evolution, regarding the choice of the primary and secondary information channels.


Brain Behavior and Evolution | 1999

Encephalization, Adaptation and Evolution of Chiroptera: A Statistical Analysis with Further Evidence for Bat Monophyly

François-Joseph Lapointe; Georg Baron; Pierre Legendre

As part of a large-scale study on brain morphometrics and adaptations in mammals, we addressed the problem of chiropteran evolution. A specific statistical framework was designed to test which of two competing hypotheses (bat monophyly vs. diphyly) is more strongly supported by quantitative brain data. Our analyses, based on 120 species, revealed that megabats and microbats were more closely related to each other than to primates, and illustrated the convergent adaptations of the brain of bats to similar trophic (i.e. feeding related) niches. Ecologically-corrected characters were then used to derive a new phylogeny which also supports the chiropteran clade. The monophyletic origin of bats is the preferred hypothesis to explain brain quantitative evolution in chiropterans and primates.


Cells Tissues Organs | 1984

Comparison of Accessory Olfactory Bulb Volumes in the Common Tree Shrew (Tupaia glis)

Heiko D. Frahm; H. Stephan; Georg Baron

The volume size of the accessory olfactory bulb (AOB) of 40 common tree shrews (Tupaia glis) was compared with regard to differences between left and right sides, males and females, and animals born in the wild and those born and raised in captivity. There were no statistically significant differences between the two sides and the two sexes, but a significant reduction of the AOB from wild to captive animals was apparent. This reduction was more pronounced in females than in males and somewhat more pronounced in the inner granular layer (layer 6) than in the other measured components (layers 1 + 2, layers 3-5). No well-founded explanation for this reduction could be given.


Archive | 1991

Brain Characteristics in Taxonomic Units

Heinz Stephan; Georg Baron; Heiko D. Frahm

Insectivora are a heteromorphous order, some members of which seem to have departed less from the form of the generalized, primitive mammalian type, and therefore, are believed to resemble the basic stock of certain mammalian lines of descent (Walker 1975).


Archive | 1991

Comparative Brain Characteristics

Heinz Stephan; Georg Baron; Heiko D. Frahm

Intraspecific variability was investigated in the four external linear measures shown in Figs. 1 and 2 and listed in Table 2. The CVs were averaged in the 35 species in which more than one individual was measured. The largest variabilities, were found to be 3.6 (%) for hemisphere length (HemL) and brain height (BH). In these two measures, it is difficult to arrive at identical values in all individuals of a species. In HemL, the caudal pole is often difficult to fix with the calipers, especially in species where it is low ventrally and projects between the lobulus petrosus (‘flocculus’) and the cerebellar hemispheres, e.g., in Chrysochloris (Figs. 8 and 20). In BH the lowest and highest extremities are not always at the same level (perpendicular to the longitudinal axis of the brain), and thus may be measured at different angles to this axis. The average CV of brain length (BL) is somewhat lower (3.3) than that of HemL and BH. BL may be influenced by the cerebellar uvula, which in different individuals may project to different levels beyond the dorsally adjacent posterior lobe of the cerebellar vermis. The lowest variability in CVs was found for brain width (BW, av. CV = 2.9). BW is easy to measure in all individuals of a species. In Chiroptera, similar differences in CVs have been found in corresponding measures by Stephan and Nelson (1981).


Archive | 1991

Brain Characteristics Related to Functional Systems

Heinz Stephan; Georg Baron; Heiko D. Frahm

Despite the importance of olfaction as a predominant sensory channel in Insectivora, numerous reports on the morphology of the insectivoran nasal cavity and intranasal epithelia suggest the existence of enormous interspecific differences (Ganeshina et al. 1957; Negus 1958 ex Quilliam 1966b; Gurtovoi 1966; Graziadei 1966; Andreescu-Nitescu 1970; Wohrmann-Repenning 1975; Wohrmann-Repenning and Meinel 1977; Schmidt and Nadolski 1979; Kuramoto et al. 1980; Larochelle 1987; Larochelle and Baron 1989a, b).

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H. Stephan

Université de Montréal

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Raymond McNeil

Université de Montréal

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H. D. Frahm

Université de Montréal

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