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  • 机译 脑和小脑皮质的发展和演变
    摘要:Cerebral cortex and cerebellar cortex both vary enormously across species in their size and complexity of convolutions. We discuss the development and evolution of cortical structures in terms of anatomy and functional organization. We propose that the distinctive shapes of cerebral and cerebellar cortex can be explained by relatively few developmental processes, notably including mechanical tension along axons and dendrites. Regarding functional organization, we show how maps of myelin content in cerebral cortex are evolutionarily conserved across primates but differ in the proportion of cortex devoted to sensory, cognitive, and other functions. We summarize recent progress and challenges in (i) parcellating cerebral cortex into a mosaic of distinct areas, (ii) distinguishing cortical areas that correspond across species from those that are present in one species but not another, and (iii) using this information along with surface-based interspecies registration to gain deeper insights into cortical evolution. We also comment on the methodological challenges imposed by the differences in anatomical and functional organization of cerebellar cortex relative to cerebral cortex.
  • 机译 弱电鱼中Δ9-四氢大麻酚的选择性和情境依赖性社会和行为影响。
    摘要:Cannabinoid (CB) receptors are widespread in the nervous system and influence a variety of behaviors. Weakly electric fish has been a useful model system in the study of the neural basis of behavior, but we know nothing of the role played by the CB system. Here, we determine the overall behavioral effect of a nonselective CB receptor agonist (i.e., Δ9-tetrahydrocannabinol, THC) in the weakly electric fish A. leptorhynchus. Using various behavioral paradigms involving social stimuli, we show that THC decreases locomotor behavior, as in many species, and influences the communication and social behavior. Across the different experiments, we found that the propensity to emit communication signals (chirps) and to seek social interactions was affected in a context-dependent manner. We explicitly tested this hypothesis by comparing the behavioral effects of THC injection in fish placed in a novel versus familiar social and physical environments. THC-injected fish were less likely to chirp than control in familiar situations but not in novel ones. The tendency to be in close proximity to other fish was affected only in novel environments with control fish clustering more than THC-injected ones. By identifying behaviors affected by CB agonists, our study can guide further comparative and neurophysiological studies of the role of the CB system using weakly electric fish as a model.
  • 机译 雌性中鳍鱼Porichthys notatus对同种和异种社会声学信号的响应的大脑激活模式
    摘要:While the peripheral auditory system of fishes has been well studied, less is known about how the fish’s brain and central auditory system process complex social acoustic signals. The plainfin midshipman fish, Porichthys notatus, has become a good species for investigating the neural basis of acoustic communication because the production and reception of acoustic signals is paramount for this species’ reproductive success. Nesting males produce long duration advertisement calls that females detect and localize amongst the noise in the intertidal zone to successfully find mates and spawn. How female midshipman are able to discriminate male advertisement calls from environmental noise and other acoustic stimuli is unknown. Using the immediate early gene product cFos as a marker for neural activity, we quantified neural activation of the ascending auditory pathway in female midshipman exposed to conspecific advertisement calls, heterospecific white seabass calls or ambient environment noise. We hypothesized that auditory hindbrain nuclei would be activated by general acoustic stimuli (ambient noise and other biotic acoustic stimuli) whereas auditory neurons in the midbrain and forebrain would be selectively activated by conspecific advertisement calls. We show that neural activation in two regions of the auditory hindbrain, the rostral intermediate division of the descending octaval nucleus and the ventral division of the secondary octaval nucleus, did not differ via cFos immunoreactive (cFos-ir) activity when exposed to different acoustic stimuli. In contrast, female midshipman exposed to conspecific advertisement calls showed greater cFos-ir in the nucleus centralis of the midbrain torus semicircularis compared to fish exposed only to ambient noise. No difference in cFos-ir was observed in the torus semicircularis of animals exposed to conspecific versus heterospecific calls. However, cFos-ir was greater in two forebrain structures that receive auditory input, the central posterior nucleus of the thalamus and the anterior tuberal hypothalamus, when exposed to conspecific calls versus exposure to either ambient noise or heterospecific calls. Our results suggest that higher order neurons in the female midshipman midbrain torus semicircularis, thalamic central posterior nucleus and hypothalamic anterior tuberal nucleus may be necessary for the discrimination of complex, specie-specific social acoustic signals. Furthermore, neurons in the central posterior and anterior tuberal nuclei are differentially activated by exposure to conspecific vs. other acoustic stimuli.
  • 机译 一些半角鲨在端脑的放射室中表达哺乳动物小胶质细胞特异性蛋白。
    摘要:Ionized calcium-binding adapter molecule 1 (Iba1), also known as allograft inflammatory factor 1 (AIF-1), is a highly conserved cytoplasmic scaffold protein. Studies strongly suggest that Iba1 is associated with immune-like reactions in all Metazoa. In the mammalian brain, it is abundantly expressed in microglial cells and is used as a reliable marker for this cell type. The present study used multiple-label microscopy and Western blotting to examine Iba1 expression in the telencephalon of two galeomorph shark species, the swellshark (Cephaloscyllium ventriosum) and the horn shark (Heterodontus francisci), a member of an ancient extant order. In the swellshark, high Iba1 expression was found in radial ependymoglial cells, many of which also expressed glial fibrillary acidic protein (GFAP). Iba1 expression was absent from most cells in the horn shark (with the possible exception of perivascular cells). The difference in Iba1 expression between the two species was supported by protein analysis. These results suggest that radial ependymoglia of the elasmobranchs may be functionally related to mammalian microglia and that Iba1 expression has undergone evolutionary changes in this cartilaginous fish group.
  • 机译 非人类灵长类动物的矢状中脑变异:人类前突神经进化的见解
    摘要:The precuneus is a major element of the superior parietal lobule, positioned on the medial side of the hemisphere and reaching the dorsal surface of the brain. It is a crucial functional region for visuospatial integration, visual imagery, and body coordination. Previously, we argued that the precuneus expanded in recent human evolution, based on a combination of paleontological, comparative, and intra-specific evidence from fossil and modern human endocasts as well as from human and chimpanzee brains. The longitudinal proportions of this region are a major source of anatomical variation among adult humans, and the main characteristic differentiating human midsagittal brain morphology from that of our closest living primate relative, the chimpanzee, being much larger in Homo sapiens. In the current shape analysis, we examine precuneus variation in non-human primates through landmark-based models, to evaluate the general pattern of variability in non-human primates, and to test whether precuneus proportions are influenced by allometric effects of brain size. Results show that precuneus proportions do not covary with brain size, and that the main difference between monkeys and apes involves a vertical expansion of the frontal and occipital regions in apes. Such differences might reflect differences in brain proportions or differences in cranial architecture. In this sample, precuneus variation is apparently not influenced by phylogenetic or allometric factors, but does vary consistently within species, at least in chimpanzees and macaques. This result further supports the hypothesis that precuneus expansion in modern humans is not merely a consequence of increasing brain size or of allometric scaling, but rather represents a species-specific morphological change in our lineage.
  • 机译 非哺乳动物脊椎动物脑干中声源定位电路的演变
    摘要:The earliest vertebrate ears likely subserved a gravistatic function for orientation in the aquatic environment. However, in addition to the detection of acceleration created by the animal’s own movements, the otolithic end organs that detect linear acceleration would have responded to particle movement created by external sources. The potential to identify and localize these external sources may have been a major selection force in the evolution of the early vertebrate ear and in the processing of sound in the central nervous system. The intrinsic physiological polarization of sensory hair cells on the otolith organs confers sensitivity to the direction of stimulation, including the direction of particle motion at auditory frequencies. In extant fishes, afferents from otolithic end organs encode the axis of particle motion, which is conveyed to the dorsal regions of first-order octaval nuclei. This directional information is further enhanced by bilateral computations in the medulla and the auditory midbrain. We propose that similar direction-sensitive neurons were present in the early aquatic tetrapods and that selection for sound localization in air acted upon pre-existing brain stem circuits like those in fishes. With movement onto land, the early tetrapods may have retained some sensitivity to particle motion, transduced by bone conduction, and later acquired new auditory papillae and tympanic hearing. Tympanic hearing arose in parallel within each of the major tetrapod lineages and would have led to increased sensitivity to a broader frequency range and to modification of the pre-existing circuitry for sound source localization.
  • 机译 感知毛细胞的外部和自身运动,从发育和进化的角度比较侧线和前庭系统
    摘要:Detection of motion is a feature essential to any living animal. In vertebrates, mechanosensory hair cells organized into the lateral line and vestibular systems are used to detect external water or head/body motion, respectively. While the neuronal components to detect these physical attributes are similar between the two sensory systems, the organizational pattern of the receptors in the periphery and the distribution of hindbrain afferent and efferent projections are adapted to the specific functions of the respective system. Here we provide a concise review comparing the functional organization of the vestibular and lateral line systems from the development of the organs to the wiring from the periphery and the first processing stages. The goal of this review is to highlight the similarities and differences to demonstrate how evolution caused a common neuronal substrate to adapt to different functions, one for the detection of external water stimuli and the generation of sensory maps and the other for the detection of self-motion and the generation of motor commands for immediate behavioral reactions.
  • 机译 亲属关系中的歌曲与欧洲八哥犬中多巴胺和神经降压素相关基因的神经表达有关
    摘要:Some animals, including songbirds, vocalize at high rates when alone or in large groups. In songbirds, vocal behavior in these contexts is important for song learning and group cohesion. It is not obviously targeted at any particular individual and is described as “undirected.” Studies suggest a role for dopamine in undirected song. The neuropeptide neurotensin can enhance dopaminergic signaling upon binding to the neurotensin receptor 1 (NTR1) and is found in regions where dopamine can influence song, including the ventral tegmental area (VTA), septum, and the song-control nucleus Area X. To begin to test the hypothesis that neurotensin and dopamine in these regions interact to influence undirected song, we used quantitative real time PCR to relate undirected singing to mRNA expression of neurotensin, NTR1, tyrosine hydroxylase (a synthetic enzyme for dopamine), and D1 and D2 receptors in male European starlings. Tyrosine hydroxylase and neurotensin expression in VTA, and neurotensin and D1 expression in Area X, positively correlated with song. Neurotensin markers also correlated positively with dopamine markers in VTA. Given the role of VTA projections to Area X in song learning, these results suggest that interactions between neurotensin and dopamine in these regions may contribute to vocal learning. In septum, NTR1 expression positively correlated with song, and neurotensin and dopamine markers were correlated, suggesting that neurotensin in this region may influence dopaminergic transmission to facilitate undirected vocalizations. Overall, these findings implicate interactions between neurotensin and dopamine in affiliative communication.
  • 机译 利用3D形状分析对软骨鱼类小脑叶片的定量分类(类:软骨鱼类)及其对进化生物学的意义
    摘要:A true cerebellum appeared at the onset of the chondrichthyan radiation and is known to be essential for executing fast, accurate, and efficient movement. In addition to a high degree of variation in size, the corpus cerebellum in this group has a high degree of variation in convolution (or foliation) and symmetry, which ranges from a smooth cerebellar surface to deep, branched convexities and folds, although the functional significance of this trait is unclear. As variation in the degree of foliation similarly exists throughout vertebrate evolution, it becomes critical to understand this evolutionary process in a wide variety of species. However, current methods are either qualitative and lack numerical rigor or are restricted to two dimensions. In this paper, a recently developed method for the characterization of shapes embedded within noisy, three-dimensional (3D) data called the spherical wave decomposition (SWD) is applied to the problem of characterizing cerebellar foliation in cartilaginous fishes. The SWD method provides a quantitative characterization of shapes in terms of well-defined mathematical functions. An additional feature of the SWD method is the construction of a statistical criterion for the optimal fit, which represents the most parsimonious choice of parameters that fits to the data, without overfitting to background noise. We propose that this optimal fit can replace a previously described qualitative visual foliation index (VFI) in cartilaginous fishes with a quantitative analogue, the cerebellar foliation index (CFI). The capability of the SWD method is demonstrated on a series of volumetric images of brains from different chondrichthyan species that span the range of foliation gradings currently described for this group. The CFI is consistent with the qualitative grading provided by the VFI, delivers a robust measure of cerebellar foliation, and can provide a quantitative basis for brain shape characterization across taxa.
  • 机译 三种掠食者的合理定位策略
    摘要:In this review we will discuss some of the neural strategies for sound localization and encoding interaural time differences (ITDs) in three predatory species of Reptilia, alligators, barn owls and geckos. Birds and crocodilians are sister groups among the extant archosaurs, while geckos are lepidosaurs. Despite the similar organization of their auditory systems, archosaurs and lizards use different strategies for encoding the ITDs that underlie localization of sound in azimuth. Barn owls encode ITD information using a place map, composed of neurons serving as labeled lines tuned for preferred spatial locations, while geckos may use a meter strategy, or population code composed of broadly sensitive neurons that represent ITD via changes in firing rate.
  • 机译 非洲蹄兔(Procavia capensis)的振动系统的细化和神经支配
    摘要:Mammalian tactile hairs are commonly found on specific, restricted regions of the body, but Florida manatees represent a unique exception, exhibiting follicle-sinus complexes (FSCs, also known as vibrissae or tactile hairs) on their entire body. The orders Sirenia (including manatees and dugongs) and Hyracoidea (hyraxes) are thought to have diverged approximately 60 mya, yet hyraxes are among the closest relatives to sirenians. We investigated the possibility that hyraxes, like manatees, are tactile specialists with vibrissae that cover the entire post-facial body. Previous studies suggested that rock hyraxes possess post-facial vibrissae in addition to pelage hair, but this observation was not verified through histological examination. Using a detailed immunohistochemical analysis, we characterized the gross morphology, innervation, and mechanoreceptors present in FSCs sampled from facial and post-facial vibrissae body regions to determine that the long post-facial hairs on the hyrax body are in fact true vibrissae. The types and relative densities of mechanoreceptors associated with each FSC also appeared to be relatively consistent between facial and post-facial FSCs. The presence of vibrissae covering the hyrax body presumably facilitates navigation in the dark caves and rocky crevices of the hyrax's environment where visual cues are limited, and may alert the animal to predatory or conspecific threats approaching the body. Furthermore, the presence of vibrissae on the post-facial body in both manatees and hyraxes indicates that this distribution may represent the ancestral condition for the supraorder Paenungulata.
  • 机译 杀手级饥饿游戏:目标规模和速度可预测寻求追踪的决定
    摘要:Predatory animals have evolved to optimally detect their prey using exquisite sensory systems such as vision, olfaction and hearing. It may not be so surprising that vertebrates, with large central nervous systems, excel at predatory behaviors. More striking is the fact that many tiny insects, with their miniscule brains and scaled down nerve cords, are also ferocious, highly successful predators. For predation, it is important to determine whether a prey is suitable before initiating pursuit. This is paramount since pursuing a prey that is too large to capture, subdue or dispatch will generate a substantial metabolic cost (in the form of muscle output) without any chance of metabolic gain (in the form of food). In addition, during all pursuits, the predator breaks its potential camouflage and thus runs the risk of becoming prey itself. Many insects use their eyes to initially detect and subsequently pursue prey. Dragonflies, which are extremely efficient predators, therefore have huge eyes with relatively high spatial resolution that allow efficient prey size estimation before initiating pursuit. However, much smaller insects, such as killer flies, also visualize and successfully pursue prey. This is an impressive behavior since the small size of the killer fly naturally limits the neural capacity and also the spatial resolution provided by the compound eye. Despite this, we here show that killer flies efficiently pursue natural (Drosophila melanogaster) and artificial (beads) prey. The natural pursuits are initiated at a distance of 7.9 ± 2.9 cm, which we show is too far away to allow for distance estimation using binocular disparities. Moreover, we show that rather than estimating absolute prey size prior to launching the attack, as dragonflies do, killer flies attack with high probability when the ratio of the prey's subtended retinal velocity and retinal size is 0.37. We also show that killer flies will respond to a stimulus of an angular size that is smaller than that of the photoreceptor acceptance angle, and that the predatory response is strongly modulated by the metabolic state. Our data thus provide an exciting example of a loosely designed matched filter to Drosophila, but one which will still generate successful pursuits of other suitable prey.
  • 机译 运动性系统中的儿茶酚胺能纤维神经支配在硬骨动物中具有两性异形,并具有其他生殖策略
    摘要:Catecholamines, which include the neurotransmitters dopamine and noradrenaline, are known modulators of sensorimotor function, reproduction, and sexually motivated behaviors across vertebrates, including vocal-acoustic communication. Recently, we demonstrated robust catecholaminergic (CA) innervation throughout the vocal-motor system in the plainfin midshipman fish, Porichtys notatus, a seasonal breeding marine teleost that produces vocal signals for social communication. There are two distinct male reproductive morphs in this species: Type I males establish nests and court females with a long duration advertisement call, while type II males sneak-spawn to steal fertilizations from type I males. Like females, type II males can only produce brief, agonistic, grunt-type vocalizations. Here, we tested the hypothesis that intrasexual differences in the numbers of CA neurons and their fiber innervation patterns throughout the vocal-motor pathway may provide neural substrates underlying divergence in reproductive behavior between morphs. We employed immunofluorescence (-ir) histochemistry to measure tyrosine hydroxylase (TH, rate-limiting enzyme in catecholamine synthesis) neuron numbers in several forebrain and hindbrain nuclei as well as TH-ir fiber innervation throughout the vocal pathway in type I and type II males collected from nests during the summer reproductive season. After controlling for differences in body size, only one group of CA neurons displayed an unequivocal difference between male morphs: the extraventricular vagal-associated TH-ir neurons, located just lateral to the dimorphic vocal motor nucleus (VMN), were significantly greater in number in type II males. In addition, type II males exhibited greater TH-ir fiber density within the VMN and greater numbers of TH-ir varicosities with putative contacts on vocal motor neurons. This strong inverse relationship between the predominant vocal morphotype and CA innervation of vocal motor neurons suggests catecholamines may function to inhibit vocal output in midshipman. These findings support catecholamines as direct modulators of vocal behavior and differential CA input appears reflective of social and reproductive behavioral divergence between male midshipman morphs.
  • 机译 睾丸激素介导热带鸟类中歌曲控制核的季节性生长
    摘要:In mid- to high-latitude songbirds seasonal reproduction is stimulated by increasing daylength accompanied by elevated plasma sex steroid levels, increased singing, and growth of the song control nuclei (SCN). Plasticity of the SCN and song behavior are primarily mediated by testosterone (T) and its metabolites in most species studied thus far. However, the majority of bird species are tropical and have less pronounced seasonal reproductive cycles. We have previously documented that equatorial rufous-collared sparrows (Zonotrichia capensis) exhibit seasonal neuroplasticity in the SCN. Manipulating T in these birds, however, did not alter singing behavior. In the current study we investigated whether T mediates plasticity of the SCN in a similar manner to temperate songbirds. In the first experiment we treated captive male birds with T or blank implants during the non-breeding season. In a second experiment we treated captive males with either blank implants, T-filled implants, T with Flutamide (FLU; an androgen receptor antagonist) or T with FLU and 1,4,6-androstatriene-3,17-dione (ATD; an estrogen synthesis inhibitor) during the breeding season. In both experiments, the volumes of brain areas HVC, Area X, and RA were measured along with singing behavior. In summary, T stimulated growth of HVC and RA and the combined effect of FLU and ATD reversed this effect in HVC. Area X was not affected by testosterone treatment in either experiment. Neither T-treated birds nor controls sang in captivity during either experiment. Together these data indicate that T mediates seasonal changes in the HVC and RA of both tropical and higher latitude bird species even if the environmental signals differ. However, unlike most higher latitude songbirds, we found no evidence that motivation to sing or growth of Area X are stimulated by T under captive conditions.
  • 机译 使用比较基因组学解码人类认知的分子进化
    摘要:Identification of genetic and molecular factors responsible for the specialized cognitive abilities of humans is expected to provide important insights into the mechanisms responsible for disorders of cognition such as autism, schizophrenia, and Alzheimer’s disease. Here, we discuss the use of comparative genomics for identifying salient genes and gene networks that may underlie cognition. We focus on the comparison of human and non-human primate brain gene expression and the utility of building gene co-expression networks for prioritizing hundreds of genes that differ in expression among the species queried. We also discuss the importance and methods for functional studies of individual genes identified. Together, this integration of comparative genomics with cellular and animal models should provide improved systems for developing effective therapeutics for disorders of cognition.
  • 机译 灵长类动物中央沟形态的演变
    摘要:The central sulcus (CS) divides the pre- and post-central gyri along the dorsal-ventral plane of which all motor and sensory functions are topographically organized. The motor-hand area of the precentral gyrus or knob has been described as the anatomical substrate of the hand in humans. Given the importance of the hand in primate evolution, here we examined the evolution of the motor-hand area by comparing the relative size and pattern of cortical folding of the CS surface area from magnetic resonance images in 131 primates including Old World monkeys, apes, and humans. We found that humans and great apes have a well-formed motor-hand area that can be seen in the variation in depth of the CS along the dorsal-ventral plane. We further found that great apes have relatively large CS surface areas compared to Old World monkeys. However, relative to great apes, humans have a small motor-hand area in terms of both adjusted and absolute surface areas.
  • 机译 哺乳动物大脑皮层的进化与发展
    摘要:Comparative developmental studies of the mammalian brain can identify key changes that can generate the diverse structures and functions of brains. We have studied how the neocortex of early mammals became organized into functionally distinct areas, and how the current level of cortical cellular and laminar specialization arose from the simpler premammalian cortex. We demonstrate the neocortical organization in early mammals that is most informative for an understanding of how the large, complex human brain evolved from a long line of ancestors. The radial and tangential enlargement of the cortex was driven by changes in the patterns of cortical neurogenesis, including alterations in the proportions of distinct progenitor types. Some cortical cell populations travel to the cortex through tangential migration, others migrate radially. A number of recent studies have begun to characterize the chick, mouse, human and non-human primate cortical transcriptome to help us understand how gene expression relates to the development, and to the anatomical and functional organization of the adult neocortex. Although all mammalian forms share the basic layout of cortical areas, the areal proportions and distributions are driven by distinct evolutionary pressures acting on sensory and motor experiences during the individual ontogenies.
  • 机译 NSF研讨会报告:通过比较各种物种的大脑图来发现神经系统组织的一般原则
    摘要:Efforts to understand nervous system structure and function have received new impetus from the federal Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Comparative analyses can contribute to this effort by leading to the discovery of general principles of neural circuit design, information processing, and gene-structure-function relationships that are not apparent from studies on single species. We here propose to extend the comparative approach to nervous system ‘maps’ comprising molecular, anatomical, and physiological data. This research will identify which neural features are likely to generalize across species, and which are unlikely to be broadly conserved. It will also suggest causal relationships between genes, development, adult anatomy, physiology, and, ultimately, behavior. These causal hypotheses can then be tested experimentally. Finally, insights from comparative research can inspire and guide technological development. To promote this research agenda, we recommend that teams of investigators coalesce around specific research questions and select a set of ‘reference species’ to anchor their comparative analyses. These reference species should be chosen not just for practical advantages, but also with regard for their phylogenetic position, behavioral repertoire, well-annotated genome, or other strategic reasons. We envision that the nervous systems of these reference species will be mapped in more detail than those of other species. The collected data may range from the molecular to the behavioral, depending on the research question. To integrate across levels of analysis and across species, standards for data collection, annotation, archiving, and distribution must be developed and respected. To that end, it will help to form networks or consortia of researchers and centers for science, technology, and education that focus on organized data collection, distribution, and training. These activities could be supported, at least in part, through existing mechanisms at NSF, NIH, and other agencies. It will also be important to develop new integrated software and database systems for cross-species data analyses. Multidisciplinary efforts to develop such analytical tools should be supported financially. Finally, training opportunities should be created to stimulate multidisciplinary, integrative research into brain structure, function, and evolution.
  • 机译 Evo-devo和灵长类动物等皮质:神经发生的固有梯度的中心组织作用。
    摘要:Spatial gradients in the initiation and termination of basic processes, such as cytogenesis, cell-type specification and dendritic maturation are ubiquitous in developing nervous systems. Such gradients can produce a niche adaptation in a particular species. For example, the high density of photoreceptors and neurons in the “area centralis” of some vertebrate retinas result from the early maturation of its center relative to its periphery. Across species, regularities in allometric scaling of brain regions can derive from conserved spatial gradients: longer neurogenesis in the alar versus the basal plate of the neural tube is associated with relatively greater expansion of alar plate derivatives in larger brains. We describe gradients of neurogenesis within the isocortex and their effects on adult cytoarchitecture within and across species. Longer duration of neurogenesis in the caudal isocortex is associated with increased neuron number and density per column relative to the rostral isocortex. Later-maturing features of single neurons, such as soma size and dendritic spine numbers reflect this gradient. Considering rodents and primates, the longer duration of isocortical neurogenesis in each species, the greater the rostral-to-caudal difference in neuron number and density per column. Extended developmental duration produces substantial, predictable changes in the architecture of the isocortex in larger brains, and presumably, a progressively changed functional organization whose properties we do not yet fully understand. Many features of isocortical architecture previously viewed as species- or niche-specific adaptations can now be integrated as the natural outcomes of spatiotemporal gradients that are deployed in larger brains.
  • 机译 双重比较方法:整合人类进化神经解剖学和神经发育障碍的证据
    摘要:The evolution of the human brain has been marked by a nearly three-fold increase in size since our divergence from the last common ancestor shared with chimpanzees and bonobos. Despite increased interest in comparative neuroanatomy and phylogenetic methods, relatively little is known regarding the effects that this enlargement has had on its internal organization, and how certain areas of the brain have differentially expanded over evolutionary time. Analyses of the microstructure of several regions of the human cortex and subcortical structures have demonstrated subtle changes at the cellular and molecular level, suggesting that the human brain is more than simply a ‘scaled-up’ primate brain. Ongoing research in comparative neuroanatomy has much to offer our understanding of human brain evolution. Through analysis of the neuroanatomical phenotype at the level of reorganization in cytoarchitecture and cellular morphology, new data continue to highlight changes in cell density and organization associated with volumetric changes in discrete regions. An understanding of the functional significance of variation in neural circuitry can further be approached through studies of atypical human development. Many neurodevelopmental disorders cause disruption in systems associated with uniquely human features of cognition, including language and social cognition. Understanding the genetic and developmental mechanisms that underlie variation in the human cognitive phenotype can help to clarify the functional significance of interspecific variation. By uniting approaches from comparative neuroanatomy and neuropathology, insights can be gained that clarify trends in human evolution. Here, we explore these lines of evidence, and their significance for understanding functional variation between species, and within neuropathological variation in the human brain.

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