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"Brain plasticity"
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The PSA-NCAM-Positive “Immature” Neurons: An Old Discovery Providing New Vistas on Brain Structural Plasticity
Studies on brain plasticity have undertaken different roads, tackling a wide range of biological processes: from small synaptic changes affecting the contacts among neurons at the very tip of their processes, to birth, differentiation, and integration of new neurons (adult neurogenesis). Stem cell-driven adult neurogenesis is an exception in the substantially static mammalian brain, yet, it has dominated the research in neurodevelopmental biology during the last thirty years. Studies of comparative neuroplasticity have revealed that neurogenic processes are reduced in large-brained mammals, including humans. On the other hand, large-brained mammals, with respect to rodents, host large populations of special “immature” neurons that are generated prenatally but express immature markers in adulthood. The history of these “immature” neurons started from studies on adhesion molecules carried out at the beginning of the nineties. The identity of these neurons as “stand by” cells “frozen” in a state of immaturity remained un-detected for long time, because of their ill-defined features and because clouded by research ef-forts focused on adult neurogenesis. In this review article, the history of these cells will be reconstructed, and a series of nuances and confounding factors that have hindered the distinction between newly generated and “immature” neurons will be addressed.
Journal Article
Hormones and brain plasticity
One of the most fascinating developments in the field of neuroscience in the second half of the 20th century was the discovery of the endogenous capacity of the brain for reorganization during adult life. Morphological and functional mechanisms underlying brain plasticity have been extensively explored and characterized. However, our understanding of the functional significance of these plastic changes is still fragmentary. This book shows that brain plasticity plays an essential role in the regulation of hormonal levels. The second aim is to propose that hormones orchestrate the multiple endogenous plastic events of the brain for the generation of adequate physiological and behavioral responses in adaptation to and in prediction of changing life conditions. The book starts by introducing the conceptual backgrounds on the interactions of hormones and brain plasticity. It then devotes itself to the analysis of the role of brain plasticity in the regulation of the activity of endocrine glands. It examines different hormonal influences on brain plasticity. Then, it goes on to cover the interactions of hormones and brain plasticity along the life cycle under physiological and pathological conditions.
eBook
An enriched environment promotes synaptic plasticity and cognitive recovery after permanent middle cerebral artery occlusion in mice
Cerebral ischemia activates an endogenous repair program that induces plastic changes in neurons. In this study, we investigated the effects of environmental enrichment on spatial learning and memory as well as on synaptic remodeling in a mouse model of chronic cerebral ischemia, produced by subjecting adult male C57BL/6 mice to permanent left middle cerebral artery occlusion. Three days postoperatively, mice were randomly assigned to the environmental enrichment and standard housing groups. Mice in the standard housing group were housed and fed a standard diet. Mice in the environmental enrichment group were housed in a cage with various toys and fed a standard diet. Then, 28 days postoperatively, spatial learning and memory were tested using the Morris water maze. The expression levels of growth-associated protein 43, synaptophysin and postsynaptic density protein 95 in the hippocampus were analyzed by western blot assay. The number of synapses was evaluated by electron microscopy. In the water maze test, mice in the environmental enrichment group had a shorter escape latency, traveled markedly longer distances, spent more time in the correct quadrant (northeast zone), and had a higher frequency of crossings compared with the standard housing group. The expression levels of growth-associated protein 43, synaptophysin and postsynaptic density protein 95 were substantially upregulated in the hippocampus in the environmental enrichment group compared with the standard housing group. Furthermore, electron microscopy revealed that environmental enrichment increased the number of synapses in the hippocampal CA1 region. Collectively, these findings suggest that environmental enrichment ameliorates the spatial learning and memory impairment induced by permanent middle cerebral artery occlusion. Environmental enrichment in mice with cerebral ischemia likely promotes cognitive recovery by inducing plastic changes in synapses.
Journal Article
Zero to birth : how the human brain is built
\"By the time a baby is born, its brain has nearly 100 billion intricately shaped neurons wired together to comprise a small, soft-matter supercomputer. How is this incredibly complicated organ built in just nine months? This book is a step-by-step guide to what we know about the development of the human brain, from its earliest embryonic origin to birth and a little beyond. Written from an experimental neuroscientist's perspective, this book provides readers with a conceptual understanding of the field of developmental neurobiology, outlining both the biological mechanisms (genetic, environmental, and stochastic) that play significant and interrelated roles in neural development, and how we have come to understand the human brain's construction and function. Highlighting the major questions that have propelled the field forward - including those pushing at the frontiers of the field today - and the stories of major discoveries made by pioneering scientists around the world, the book describes how the structures and mechanisms of the developing brain were discovered. Chapters progress chronologically, tracking the actual growth and development of the human brain from conception to just after birth, as well as the history of how these mechanisms were revealed. Throughout, findings from studies of model organisms, such as nematodes, flies, frogs, fish, birds, mice, and sometimes non-human primates, are woven into the narrative and put into the context of a human embryo or fetus, as there are clear indications that the same processes involving the same genes are found across species. The book concludes with a discussion of what makes individual brains unique and how research on early neural development is helping us better understand the genetic and embryonic origins of many neurological and cognitive traits that only reveal themselves later in life\"-- Provided by publisher.
BOOK
Why and how does early adversity influence development? Toward an integrated model of dimensions of environmental experience
Two extant frameworks – the harshness-unpredictability model and the threat-deprivation model – attempt to explain which dimensions of adversity have distinct influences on development. These models address, respectively, why, based on a history of natural selection, development operates the way it does across a range of environmental contexts, and how the neural mechanisms that underlie plasticity and learning in response to environmental experiences influence brain development. Building on these frameworks, we advance an integrated model of dimensions of environmental experience, focusing on threat-based forms of harshness, deprivation-based forms of harshness, and environmental unpredictability. This integrated model makes clear that the why and the how of development are inextricable and, together, essential to understanding which dimensions of the environment matter. Core integrative concepts include the directedness of learning, multiple levels of developmental adaptation to the environment, and tradeoffs between adaptive and maladaptive developmental responses to adversity. The integrated model proposes that proximal and distal cues to threat-based and deprivation-based forms of harshness, as well as unpredictability in those cues, calibrate development to both immediate rearing environments and broader ecological contexts, current and future. We highlight actionable directions for research needed to investigate the integrated model and advance understanding of dimensions of environmental experience.
Journal Article
Fractality of sensations and the brain health: the theory linking neurodegenerative disorder with distortion of spatial and temporal scale-invariance and fractal complexity of the visible world
The theory that ties normal functioning and pathology of the brain and visual system with the spatial-temporal structure of the visual and other sensory stimuli is described for the first time in the present study. The deficit of fractal complexity of environmental influences can lead to the distortion of fractal complexity in the visual pathways of the brain and abnormalities of development or aging. The use of fractal light stimuli and fractal stimuli of other modalities can help to restore the functions of the brain, particularly in the elderly and in patients with neurodegenerative disorders or amblyopia. Non-linear dynamics of these physiological processes have a strong base of evidence, which is seen in the impaired fractal regulation of rhythmic activity in aged and diseased brains. From birth to old age, we live in a non-linear world, in which objects and processes with the properties of fractality and non-linearity surround us. Against this background, the evolution of man took place and all periods of life unfolded. Works of art created by man may also have fractal properties. The positive influence of music on cognitive functions is well-known. Insufficiency of sensory experience is believed to play a crucial role in the pathogenesis of amblyopia and age-dependent diseases. The brain is very plastic in its early development, and the plasticity decreases throughout life. However, several studies showed the possibility to reactivate the adult's neuroplasticity in a variety of ways. We propose that a non-linear structure of sensory information on many spatial and temporal scales is crucial to the brain health and fractal regulation of physiological rhythms. Theoretical substantiation of the author's theory is presented. Possible applications and the future research that can experimentally confirm or refute the theoretical concept are considered.
Journal Article
Non-Invasive Brain Stimulation: Enhancing Motor and Cognitive Functions In Healthy Old Subjects
Healthy aging is accompanied by changes in cognitive and motor functions that result in impairment of activities of daily living. This process involves a number of modifications in the brain and is associated with metabolic, structural, and physiological changes; some of these serving as adaptive responses to the functional declines. Up to date there are no universally accepted strategies to ameliorate declining functions in this population. An essential basis to develop such strategies is a better understanding of neuroplastic changes during healthy aging. In this context, non-invasive brain stimulation techniques, such as transcranial direct current or transcranial magnetic stimulation, provide an attractive option to modulate cortical neuronal assemblies, even with subsequent changes in neuroplasticity. Thus, in the present review we discuss the use of these techniques as a tool to study underlying cortical mechanisms during healthy aging and as an interventional strategy to enhance declining functions and learning abilities in aged subjects.
Journal Article