Comme je vous demande des références précises, je vous en offre sur ce point. Toutes récentes, toutes en partie sur l'évolution du cerveau humain, certaines élaborant sur le développement:
Kornack DR (2000) Neurogenesis and the evolution of cortical diversity: mode, tempo, and partitioning during development and persistence in adulthood. Brain Behav Evol;55(6):336-44
The mammalian cerebral cortex varies enormously in absolute and relative size across species. These size differences reflect phyletic differences in the number and organization of cortical neurons, which in turn imply evolutionary changes in the developmental program that generates these neurons. Whereas patterns of symmetric and asymmetric modes of progenitor cell division during cortical neurogenesis are widely conserved among species, other proliferation parameters, including the timing and number of cell divisions, vary considerably. This variation contributes to the development of cortical size differences in mammals in general, and the expansion of neocortex in anthropoid primates (monkeys, apes, and humans) in particular. The disproportionate enlargement of anthropoid neocortex might also arise from regional 'border-shifting' within the embryonic telencephalon, causing expansion of the neurogenic region allocated for producing neocortex and concomitant diminution of neighboring olfactory regions. Neurogenesis also shows substantial phyletic differences in adult hippocampus, an archicortical structure. Therefore, variation in neurogenesis across species is not only a feature of early development, but is also a trait of adult cortical diversity.
Krubitzer L, Huffman KJ (2000) Arealization of the neocortex in mammals: genetic and epigenetic contributions to the phenotype. Brain Behav Evol;55(6):322-35
The neocortex is composed of areas that are functionally, anatomically and histochemically distinct. In comparison to most other mammals, humans have an expanded neocortex, with a pronounced increase in the number of cortical areas. This expansion underlies many complex behaviors associated with human capabilities including perception, cognition, language and volitional motor responses. In the following review we consider data from comparative studies as well as from developmental studies to gain insight into the mechanisms involved in arealization, and discuss how these mechanisms may have been modified in different lineages over time to produce the remarkable degree of organizational variability observed in the neocortex of mammals. Because any phenotype is a result of the complex interactions between genotypic influences and environmental factors, we also consider environmental, or epigenetic, contributions to the organization of the neocortex.
Hof PR, Glezer II, Nimchinsky EA, Erwin JM (2000) Neurochemical and cellular specializations in the mammalian neocortex reflect phylogenetic relationships: evidence from primates, cetaceans, and artiodactyls. Brain Behav Evol;55(6):300-10
Most of the available data on the cytoarchitecture of the cerebral cortex in mammals rely on Nissl, Golgi, and myelin stains and few studies have explored the differential morphologic and neurochemical phenotypes of neuronal populations. In addition, the majority of studies addressing the distribution and morphology of identified neuronal subtypes have been performed in common laboratory animals such as the rat, mouse, cat, and macaque monkey, as well as in postmortem analyses in humans. Several neuronal markers, such as neurotransmitters or structural proteins, display a restricted cellular distribution in the mammalian brain, and recently, certain cytoskeletal proteins and calcium-binding proteins have emerged as reliable markers for morphologically distinct subpopulations of neurons in a large number of mammalian species. In this article, we review the morphologic characteristics and distribution of three calcium-binding proteins, parvalbumin, calbindin, and calretinin, and of the neurofilament protein triplet, a component of the neuronal cytoskeleton, to provide an overview of the presence and cellular typology of these proteins in the neocortex of various mammalian taxa. Considering the remarkable diversity in gross morphological patterns and neuronal organization that occurred during the evolution of mammalian neocortex, the distribution of these neurochemical markers may help define taxon-specific patterns. In turn, such patterns can be used as reliable phylogenetic traits to assess the degree to which neurochemical specialization of neurons, as well as their regional and laminar distribution in the neocortex, represent derived or ancestral features, and differ in certain taxa from the laboratory species that are most commonly studied.
Uylings HH (2000) Development of the cerebral cortex in rodents and Man. Eur J Morphol, 38(5):309-12
Studies mainly in rodents and man have contributed to new vistas on mammalian cerebral cortex development. Due to the much longer development in man and the larger size of the human brain, particular features (such as the existence of the subplate and tangential migration) were first detected in the human cortex. In addition, experimental techniques that can only be applied in nonhuman mammals revealed the pattern of neuronal generation, and demonstrated the different ways of neuronal migration and the formation of neuronal pathways. In this short review the present vistas on neuronal generation and migration, and the occurrence of transient layers are summarized.
Smeets WJ, Marin O, Gonzalez A (2000) Evolution of the basal ganglia: new perspectives through a comparative approach. J Anat;196 ( Pt 4):501-17
The basal ganglia (BG) have received much attention during the last 3 decades mainly because of their clinical relevance. Our understanding of their structure, organisation and function in terms of chemoarchitecture, compartmentalisation, connections and receptor localisation has increased equally. Most of the research has been focused on the mammalian BG, but a considerable number of studies have been carried out in nonmammalian vertebrates, in particular reptiles and birds. The BG of the latter 2 classes of vertebrates, which together with mammals constitute the amniotic vertebrates, have been thoroughly studied by means of tract-tracing and immunohistochemical techniques. The terminology used for amniotic BG structures has frequently been adopted to indicate putative corresponding structures in the brain of anamniotes, i.e. amphibians and fishes, but data for such a comparison were, until recently, almost totally lacking. It has been proposed several times that the occurrence of well developed BG structures probably constitutes a landmark in the anamniote-amniote transition. However, our recent studies of connections, chemoarchitecture and development of the basal forebrain of amphibians have revealed that tetrapod vertebrates share a common pattern of BG organisation. This pattern includes the existence of dorsal and ventral striatopallidal systems, reciprocal connections between the striatopallidal complex and the diencephalic and mesencephalic basal plate (striatonigral and nigrostriatal projections), and descending pathways from the striatopallidal system to the midbrain tectum and reticular formation. The connectional similarities are paralleled by similarities in the distribution of chemical markers of striatal and pallidal structures such as dopamine, substance P and enkephalin, as well as by similarities in development and expression of homeobox genes. On the other hand, a major evolutionary trend is the progressive involvement of the cortex in the processing of the thalamic sensory information relayed to the BG of tetrapods. By using the comparative approach, new insights have been gained with respect to certain features of the BG of vertebrates in general, such as the segmental organisation of the midbrain dopaminergic cell groups, the occurrence of large numbers of dopaminergic cell bodies within the telencephalon itself and the variability in, among others, connectivity and chemoarchitecture. However, the intriguing question whether the basal forebrain organisation of nontetrapods differs essentially from that observed in tetrapods still needs to be answered.
Je vous signale que votre dossier, même s'il est plein de "peut-être", est toujours vide de preuves. C'est ça le point le plus négatif de la théorie de la Création: une profonde stérilité factuelle.
Jean-François