This study presents the results of an examination of the mummified brain of a pleistocene Woolly ... more This study presents the results of an examination of the mummified brain of a pleistocene Woolly mammoth (Mammuthus primigenius) recovered from the Yakutian permafrost in Siberia, Russia. This unique specimen (39 440 - 38 850 years BP) provides the rare opportunity to compare the brain morphology of this extinct species with a related extant species, the African elephant (Loxodonta africana). An anatomical description of the preserved brain of the Woolly mammoth is provided, along with a series of quantitative analyses of various brain structures. These descriptions are based on visual inspection of the actual specimen as well as the qualitative and quantitative comparison of CT imaging data obtained for the Woolly mammoth in comparison to MR imaging data from three African elephant brains. In general, the brain of the Woolly mammoth specimen examined, estimated to weigh between 4230 - 4340 g, showed the typical shape, size and gross structures observed in extant elephants. The quantitative comparative analyses of various features of the brain, such as the amygdala, corpus callosum, cerebellum and gyrnecephalic index, all indicate that the brain of the Woolly mammoth specimen examined has many similarities with that of modern African elephants. The analysis provided herein indicates that a specific brain type representative of the Elephantidae is likely to be a feature of this mammalian family. In addition, the extensive similarities between the Woolly mammoth brain with the African elephant brain indicates that the specializations observed in the extant elephant brain are likely to have been present in the Woolly mammoth. This article is protected by copyright. All rights reserved.
Over the past decade much controversy has surrounded the hypothesis that the megachiroptera, or m... more Over the past decade much controversy has surrounded the hypothesis that the megachiroptera, or megabats, share unique neural characteristics with the primates. These observations, which include similarities in visual pathways, have suggested that the megabats are more closely related to the primates than to the other group of the Chiropteran order, the microbats, and suggests a diphyletic origin of the Chiroptera. To contribute data relevant to this debate, we used immunohistochemical techniques to reveal the architecture of the neuromodulatory systems of the Egyptian rousette (Rousettus aegypticus), an echolocating megabat. Our findings revealed many similarities in the nuclear parcellation of the cholinergic, putative catecholaminergic and serotonergic systems with that seen in other mammals including the microbat. However, there were 11 discrete nuclei forming part of these systems in the brain of the megabat studied that were not evident in an earlier study of a microbat. The o...
The current study was designed to reveal the retinotectal pathway in the brain of the echolocatin... more The current study was designed to reveal the retinotectal pathway in the brain of the echolocating megabat Rousettus aegyptiacus. The retinotectal pathway of other species of megabats shows the primate-like pattern of decussation in the retina; however, it has been reported that the echolocating Rousettus did not share this feature. To test this prior result we injected fluorescent dextran tract
The present study describes the location and nuclear organization of the serotonergic system in a... more The present study describes the location and nuclear organization of the serotonergic system in a representative of the order Crocodylia, the Nile crocodile (Crocodylus niloticus). We found evidence for serotonergic neurons in three regions of the brain, including the diencephalon, rostral and caudal brainstem, as previously reported in several other species of reptile. Within the diencephalon we found neurons in
The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serot... more The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serotonergic systems within the brain of the greater canerat (sometimes spelt cane rat) were identified following immunohistochemistry for tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems when comparing those of the greater canerat
The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serot... more The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serotonergic systems within the brain of the highveld gerbil were identified following immunohistochemistry for tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems when comparing those of the highveld gerbil with those of the
Although the basic morphological characteristics of neurons in the cerebellar cortex have been do... more Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee), carnivores (Siberian tiger, clouded leopard), cetartiodactyls (humpback whale, giraffe) and primates (human, common chimpanzee). Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317) of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant) and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967) and rodents (Palay and Chan-Palay, 1974), although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures.
This study presents the results of an examination of the mummified brain of a pleistocene Woolly ... more This study presents the results of an examination of the mummified brain of a pleistocene Woolly mammoth (Mammuthus primigenius) recovered from the Yakutian permafrost in Siberia, Russia. This unique specimen (39 440 - 38 850 years BP) provides the rare opportunity to compare the brain morphology of this extinct species with a related extant species, the African elephant (Loxodonta africana). An anatomical description of the preserved brain of the Woolly mammoth is provided, along with a series of quantitative analyses of various brain structures. These descriptions are based on visual inspection of the actual specimen as well as the qualitative and quantitative comparison of CT imaging data obtained for the Woolly mammoth in comparison to MR imaging data from three African elephant brains. In general, the brain of the Woolly mammoth specimen examined, estimated to weigh between 4230 - 4340 g, showed the typical shape, size and gross structures observed in extant elephants. The quantitative comparative analyses of various features of the brain, such as the amygdala, corpus callosum, cerebellum and gyrnecephalic index, all indicate that the brain of the Woolly mammoth specimen examined has many similarities with that of modern African elephants. The analysis provided herein indicates that a specific brain type representative of the Elephantidae is likely to be a feature of this mammalian family. In addition, the extensive similarities between the Woolly mammoth brain with the African elephant brain indicates that the specializations observed in the extant elephant brain are likely to have been present in the Woolly mammoth. This article is protected by copyright. All rights reserved.
Over the past decade much controversy has surrounded the hypothesis that the megachiroptera, or m... more Over the past decade much controversy has surrounded the hypothesis that the megachiroptera, or megabats, share unique neural characteristics with the primates. These observations, which include similarities in visual pathways, have suggested that the megabats are more closely related to the primates than to the other group of the Chiropteran order, the microbats, and suggests a diphyletic origin of the Chiroptera. To contribute data relevant to this debate, we used immunohistochemical techniques to reveal the architecture of the neuromodulatory systems of the Egyptian rousette (Rousettus aegypticus), an echolocating megabat. Our findings revealed many similarities in the nuclear parcellation of the cholinergic, putative catecholaminergic and serotonergic systems with that seen in other mammals including the microbat. However, there were 11 discrete nuclei forming part of these systems in the brain of the megabat studied that were not evident in an earlier study of a microbat. The o...
The current study was designed to reveal the retinotectal pathway in the brain of the echolocatin... more The current study was designed to reveal the retinotectal pathway in the brain of the echolocating megabat Rousettus aegyptiacus. The retinotectal pathway of other species of megabats shows the primate-like pattern of decussation in the retina; however, it has been reported that the echolocating Rousettus did not share this feature. To test this prior result we injected fluorescent dextran tract
The present study describes the location and nuclear organization of the serotonergic system in a... more The present study describes the location and nuclear organization of the serotonergic system in a representative of the order Crocodylia, the Nile crocodile (Crocodylus niloticus). We found evidence for serotonergic neurons in three regions of the brain, including the diencephalon, rostral and caudal brainstem, as previously reported in several other species of reptile. Within the diencephalon we found neurons in
The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serot... more The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serotonergic systems within the brain of the greater canerat (sometimes spelt cane rat) were identified following immunohistochemistry for tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems when comparing those of the greater canerat
The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serot... more The distribution, morphology and nuclear subdivisions of the putative catecholaminergic and serotonergic systems within the brain of the highveld gerbil were identified following immunohistochemistry for tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems when comparing those of the highveld gerbil with those of the
Although the basic morphological characteristics of neurons in the cerebellar cortex have been do... more Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee), carnivores (Siberian tiger, clouded leopard), cetartiodactyls (humpback whale, giraffe) and primates (human, common chimpanzee). Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317) of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant) and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967) and rodents (Palay and Chan-Palay, 1974), although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures.
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