Dara L. Dickstein, John H. Morrison, and Patrick R. Hof
- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780195328875
- eISBN:
- 9780199864836
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195328875.003.0003
- Subject:
- Neuroscience, Techniques, Development
Alzheimer's disease (AD) is characterized by extensive, yet selective, neuron death in the cerebral neocortex leading to dramatic decline in cognitive abilities and memory. A more modest disruption ...
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Alzheimer's disease (AD) is characterized by extensive, yet selective, neuron death in the cerebral neocortex leading to dramatic decline in cognitive abilities and memory. A more modest disruption of memory occurs frequently in normal aging, in humans and in animal models. Significant neuron death does not appear to be the cause of such age-related memory deficits, but in AD, hippocampal and long association corticocortical circuits are devastated. Evidence from rodent and nonhuman primate models reveals that these same circuits exhibit subtle age-related changes in neurochemical phenotype, dendritic and spine morphology, and synaptic integrity that correlate with impaired function. Molecular alterations of synapses, such as shifts in expression of excitatory receptors, also contribute to these deficits. These brain regions are also responsive to circulating estrogen levels. Interactions between reproductive senescence and brain aging may affect cortical synaptic transmission, implying that certain synaptic alterations in aging may be reversible. As such, integrity of spines and synapses may reflect age-related memory decline, whereas the loss of select cortical circuits is a crucial substrate for functional decline in AD.Less
Alzheimer's disease (AD) is characterized by extensive, yet selective, neuron death in the cerebral neocortex leading to dramatic decline in cognitive abilities and memory. A more modest disruption of memory occurs frequently in normal aging, in humans and in animal models. Significant neuron death does not appear to be the cause of such age-related memory deficits, but in AD, hippocampal and long association corticocortical circuits are devastated. Evidence from rodent and nonhuman primate models reveals that these same circuits exhibit subtle age-related changes in neurochemical phenotype, dendritic and spine morphology, and synaptic integrity that correlate with impaired function. Molecular alterations of synapses, such as shifts in expression of excitatory receptors, also contribute to these deficits. These brain regions are also responsive to circulating estrogen levels. Interactions between reproductive senescence and brain aging may affect cortical synaptic transmission, implying that certain synaptic alterations in aging may be reversible. As such, integrity of spines and synapses may reflect age-related memory decline, whereas the loss of select cortical circuits is a crucial substrate for functional decline in AD.
Franck Polleux and Anirvan Ghosh
- Published in print:
- 2007
- Published Online:
- March 2012
- ISBN:
- 9780198566564
- eISBN:
- 9780191724206
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198566564.003.0004
- Subject:
- Neuroscience, Molecular and Cellular Systems
Information processing in neurons is critically dependent on dendritic morphology. The overall extent and orientation of dendrites determines the kinds of input a neuron receives. Fine dendritic ...
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Information processing in neurons is critically dependent on dendritic morphology. The overall extent and orientation of dendrites determines the kinds of input a neuron receives. Fine dendritic appendages called spines act as subcellular compartments devoted to processing synaptic information, and the dendritic branching pattern determines the efficacy with which synaptic information is transmitted to the soma. The development of the dendritic tree is influenced by a number of factors. Studies in Drosophila have identified key components of the genetic program that regulates dendritic morphogenesis. Parallel studies in vertebrates have revealed that extracellular signals and neuronal activity exert a major influence on the growth and branching of dendrites and the formation of dendritic spines. The identification of genes that mediate these processes is providing important insight into the molecular mechanisms of dendritic morphogenesis.Less
Information processing in neurons is critically dependent on dendritic morphology. The overall extent and orientation of dendrites determines the kinds of input a neuron receives. Fine dendritic appendages called spines act as subcellular compartments devoted to processing synaptic information, and the dendritic branching pattern determines the efficacy with which synaptic information is transmitted to the soma. The development of the dendritic tree is influenced by a number of factors. Studies in Drosophila have identified key components of the genetic program that regulates dendritic morphogenesis. Parallel studies in vertebrates have revealed that extracellular signals and neuronal activity exert a major influence on the growth and branching of dendrites and the formation of dendritic spines. The identification of genes that mediate these processes is providing important insight into the molecular mechanisms of dendritic morphogenesis.
Zachary F. Mainen and Larry F. Abbott
- Published in print:
- 2007
- Published Online:
- March 2012
- ISBN:
- 9780198566564
- eISBN:
- 9780191724206
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198566564.003.0018
- Subject:
- Neuroscience, Molecular and Cellular Systems
Most synapses are made onto dendrites, and most excitatory connections are made onto dendritic spines. Synaptic plasticity is thus an intrinsically dendritic phenomenon, but the functional ...
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Most synapses are made onto dendrites, and most excitatory connections are made onto dendritic spines. Synaptic plasticity is thus an intrinsically dendritic phenomenon, but the functional significance of the structural, electrical, and molecular properties of dendrites for synaptic plasticity is still very poorly understood. Do dendrites have a computational or cell biological role in the modification of synaptic strength that is more than circumstantial? This chapter aims to summarize experimental data and theoretical considerations that may be relevant to the role of dendrites in synaptic plasticity. The focus is on associative Hebbian synaptic plasticity, including spike-timing-dependent forms, mediated by NMDA receptor activation.Less
Most synapses are made onto dendrites, and most excitatory connections are made onto dendritic spines. Synaptic plasticity is thus an intrinsically dendritic phenomenon, but the functional significance of the structural, electrical, and molecular properties of dendrites for synaptic plasticity is still very poorly understood. Do dendrites have a computational or cell biological role in the modification of synaptic strength that is more than circumstantial? This chapter aims to summarize experimental data and theoretical considerations that may be relevant to the role of dendrites in synaptic plasticity. The focus is on associative Hebbian synaptic plasticity, including spike-timing-dependent forms, mediated by NMDA receptor activation.
Fritjof Helmchen and U. Valentin Nägerl
- Published in print:
- 2016
- Published Online:
- May 2016
- ISBN:
- 9780198745273
- eISBN:
- 9780191819735
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198745273.003.0010
- Subject:
- Neuroscience, Sensory and Motor Systems, Molecular and Cellular Systems
Dendrites have both an electrical and a biochemical character, which are closely linked. This chapter discusses dendritic structures as compartments for chemical signals such as concentration changes ...
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Dendrites have both an electrical and a biochemical character, which are closely linked. This chapter discusses dendritic structures as compartments for chemical signals such as concentration changes of ions or other second messengers, which control enzyme activity and signaling cascades. It focuses on the following question: to what extent can these signals be confined to only part of the dendritic tree or to dendritic spines? Such ‘compartmentalization’ is considered the basis of local modifications of dendritic properties, in particular to achieve input-specific changes in synaptic strength. General factors that affect compartmentalization of chemical signals are first discussed, including diffusion, intracellular binding, and removal mechanisms. Examples are given of measurements of dendritic ion and second messenger signaling, with the main focus on calcium signaling, for which the most detailed information is available from imaging studies. Subsequently, in an attempt to define functional units, an overview of the different spatial scales of dendritic compartmentalization is given, spanning a range of three orders of magnitude. Finally, there are examples of how chemical signals are used for dendritic information processing.Less
Dendrites have both an electrical and a biochemical character, which are closely linked. This chapter discusses dendritic structures as compartments for chemical signals such as concentration changes of ions or other second messengers, which control enzyme activity and signaling cascades. It focuses on the following question: to what extent can these signals be confined to only part of the dendritic tree or to dendritic spines? Such ‘compartmentalization’ is considered the basis of local modifications of dendritic properties, in particular to achieve input-specific changes in synaptic strength. General factors that affect compartmentalization of chemical signals are first discussed, including diffusion, intracellular binding, and removal mechanisms. Examples are given of measurements of dendritic ion and second messenger signaling, with the main focus on calcium signaling, for which the most detailed information is available from imaging studies. Subsequently, in an attempt to define functional units, an overview of the different spatial scales of dendritic compartmentalization is given, spanning a range of three orders of magnitude. Finally, there are examples of how chemical signals are used for dendritic information processing.
Hamilton Andrew and Zito Karen
- Published in print:
- 2011
- Published Online:
- August 2013
- ISBN:
- 9780262015233
- eISBN:
- 9780262295444
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262015233.003.0011
- Subject:
- Neuroscience, Research and Theory
This chapter discusses some of the most exciting recent discoveries concerning the mechanisms of spine synapse plasticity and reviews the most intriguing questions which still loom over these tiny ...
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This chapter discusses some of the most exciting recent discoveries concerning the mechanisms of spine synapse plasticity and reviews the most intriguing questions which still loom over these tiny cytoplasmic extrusions. It reveals that the sensory experience affects spine motility. This chapter shows that the formation of dendritic spines may be potentiated around sites of high synaptic activity. It supports the hypothesis that spine morphological changes underlie experience-dependent changes in neuronal circuits.Less
This chapter discusses some of the most exciting recent discoveries concerning the mechanisms of spine synapse plasticity and reviews the most intriguing questions which still loom over these tiny cytoplasmic extrusions. It reveals that the sensory experience affects spine motility. This chapter shows that the formation of dendritic spines may be potentiated around sites of high synaptic activity. It supports the hypothesis that spine morphological changes underlie experience-dependent changes in neuronal circuits.
Samuel S.-H. Wang, Anthony E. Ambrosini, and Gayle M. Wittenberg
- Published in print:
- 2016
- Published Online:
- May 2016
- ISBN:
- 9780198745273
- eISBN:
- 9780191819735
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198745273.003.0002
- Subject:
- Neuroscience, Sensory and Motor Systems, Molecular and Cellular Systems
Dendrites, the neuronal processes that receive synaptic inputs, are found in all nervous systems. The great diversity of dendrites, both within individual species and across phylogeny, reflects their ...
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Dendrites, the neuronal processes that receive synaptic inputs, are found in all nervous systems. The great diversity of dendrites, both within individual species and across phylogeny, reflects their adaptation to particular functional roles. This chapter explores this diversity to consider dendrites from an evolutionary perspective. The evidence that dendrites scale across phylogeny to preserve the number of synapses per neuron is reviewed, as well as the architecture of local microcircuits, including the number of neurons in a single neocortical column. Dendritic spines may have originated to form and regulate connections, and later acquired the function of maximizing information storage in densely packed neuropil. These observations are consistent with the unifying principle that dendrites have adapted to keep circuit-level function the same, even though per-gram metabolic rates vary widely. Finally, the chapter considers an emerging area of investigation in normal function and in disease: molecular and developmental mechanisms regulating dendritic form, the targets upon which selection has acted.Less
Dendrites, the neuronal processes that receive synaptic inputs, are found in all nervous systems. The great diversity of dendrites, both within individual species and across phylogeny, reflects their adaptation to particular functional roles. This chapter explores this diversity to consider dendrites from an evolutionary perspective. The evidence that dendrites scale across phylogeny to preserve the number of synapses per neuron is reviewed, as well as the architecture of local microcircuits, including the number of neurons in a single neocortical column. Dendritic spines may have originated to form and regulate connections, and later acquired the function of maximizing information storage in densely packed neuropil. These observations are consistent with the unifying principle that dendrites have adapted to keep circuit-level function the same, even though per-gram metabolic rates vary widely. Finally, the chapter considers an emerging area of investigation in normal function and in disease: molecular and developmental mechanisms regulating dendritic form, the targets upon which selection has acted.
Gordon M. Shepherd (ed.)
- Published in print:
- 2004
- Published Online:
- May 2009
- ISBN:
- 9780195159561
- eISBN:
- 9780199864447
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195159561.001.1
- Subject:
- Neuroscience, Molecular and Cellular Systems, Development
Synapses are the contact sites that enable neurons to form connections between each other in order to transmit and process neural information. Synaptic organization is concerned with the principles ...
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Synapses are the contact sites that enable neurons to form connections between each other in order to transmit and process neural information. Synaptic organization is concerned with the principles by which neurons form circuits that mediate the specific functional operations of different brain regions. One of the aims of this book is to show that the study of synaptic organization—in its full multidisciplinary, multilevel, and theoretical dimension—is a powerful means of integrating brain information to give clear insights into the neural basis of behavior. This book, which has been revised in this the fifth edition, details local circuits in the different regions of the brain. The results of the mouse and human genome projects are incorporated. Also the book contains support from neuroscience databases. Among the new advances covered are 2-photon confocal laser microscopy of dendrites and dendritic spines, biochemical analyses, and dual patch and multielectrode recordings, applied together with an increasing range of behavioral and gene-targeting methods.Less
Synapses are the contact sites that enable neurons to form connections between each other in order to transmit and process neural information. Synaptic organization is concerned with the principles by which neurons form circuits that mediate the specific functional operations of different brain regions. One of the aims of this book is to show that the study of synaptic organization—in its full multidisciplinary, multilevel, and theoretical dimension—is a powerful means of integrating brain information to give clear insights into the neural basis of behavior. This book, which has been revised in this the fifth edition, details local circuits in the different regions of the brain. The results of the mouse and human genome projects are incorporated. Also the book contains support from neuroscience databases. Among the new advances covered are 2-photon confocal laser microscopy of dendrites and dendritic spines, biochemical analyses, and dual patch and multielectrode recordings, applied together with an increasing range of behavioral and gene-targeting methods.
Rafael Yuste
- Published in print:
- 2010
- Published Online:
- August 2013
- ISBN:
- 9780262013505
- eISBN:
- 9780262259286
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262013505.003.0001
- Subject:
- Neuroscience, Research and Theory
This chapter aims to integrate all current knowledge on dendritic spines, and provide information on the important features of the circuits in which they operate. It discusses the various aspects of ...
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This chapter aims to integrate all current knowledge on dendritic spines, and provide information on the important features of the circuits in which they operate. It discusses the various aspects of the biology of the spines. It then presents a brief summary of each chapter on the book, which explores the different physiological functions of the spine.Less
This chapter aims to integrate all current knowledge on dendritic spines, and provide information on the important features of the circuits in which they operate. It discusses the various aspects of the biology of the spines. It then presents a brief summary of each chapter on the book, which explores the different physiological functions of the spine.
Rafael Yuste
- Published in print:
- 2010
- Published Online:
- August 2013
- ISBN:
- 9780262013505
- eISBN:
- 9780262259286
- Item type:
- book
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262013505.001.0001
- Subject:
- Neuroscience, Research and Theory
Most neurons in the brain are covered by dendritic spines, small protrusions that arise from dendrites, covering them like leaves on a tree. But a hundred and twenty years after spines were first ...
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Most neurons in the brain are covered by dendritic spines, small protrusions that arise from dendrites, covering them like leaves on a tree. But a hundred and twenty years after spines were first described by Ramón y Cajal, their function is still unclear. Dozens of different functions have been proposed, from Cajal's idea that they enhance neuronal interconnectivity to hypotheses that spines serve as plasticity machines, neuroprotective devices, or even digital logic elements. This book attempts to solve the “spine problem,” searching for the fundamental function of spines. The text does this by examining many aspects of spine biology that been sources of fascination over the years, including their structure, development, motility, plasticity, biophysical properties, and calcium compartmentalization. it argues that we may never understand how the brain works without understanding the specific function of spines. The book offers a synthesis of the information that has been gathered on spines (much of which comes from studies of the mammalian cortex), linking their function with the computational logic of the neuronal circuits that use them. It argues that once viewed from the circuit perspective, all the pieces of the spine puzzle fit together nicely into a single, overarching function. The book connects these two topics, integrating current knowledge of spines with that of key features of the circuits in which they operate. It concludes with a speculative chapter on the computational function of spines, searching for the ultimate logic of their existence in the brain.Less
Most neurons in the brain are covered by dendritic spines, small protrusions that arise from dendrites, covering them like leaves on a tree. But a hundred and twenty years after spines were first described by Ramón y Cajal, their function is still unclear. Dozens of different functions have been proposed, from Cajal's idea that they enhance neuronal interconnectivity to hypotheses that spines serve as plasticity machines, neuroprotective devices, or even digital logic elements. This book attempts to solve the “spine problem,” searching for the fundamental function of spines. The text does this by examining many aspects of spine biology that been sources of fascination over the years, including their structure, development, motility, plasticity, biophysical properties, and calcium compartmentalization. it argues that we may never understand how the brain works without understanding the specific function of spines. The book offers a synthesis of the information that has been gathered on spines (much of which comes from studies of the mammalian cortex), linking their function with the computational logic of the neuronal circuits that use them. It argues that once viewed from the circuit perspective, all the pieces of the spine puzzle fit together nicely into a single, overarching function. The book connects these two topics, integrating current knowledge of spines with that of key features of the circuits in which they operate. It concludes with a speculative chapter on the computational function of spines, searching for the ultimate logic of their existence in the brain.
Rafael Yuste
- Published in print:
- 2010
- Published Online:
- August 2013
- ISBN:
- 9780262013505
- eISBN:
- 9780262259286
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262013505.003.0002
- Subject:
- Neuroscience, Research and Theory
This chapter narrates the discovery of dendritic spines. It begins with Santiago Ramón y Cajal, a Spanish professor of Pathology and Histology, and his work entitled Estractura delos centros ...
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This chapter narrates the discovery of dendritic spines. It begins with Santiago Ramón y Cajal, a Spanish professor of Pathology and Histology, and his work entitled Estractura delos centros nerviosos de la aves (Structure of the Nervous Centers in Birds) and how he discovered the spines using the Golgi technique. Cajal defined “spine” on the spines of a rose bush, as it resembled one when he first investigated it in Purkinje cells.Less
This chapter narrates the discovery of dendritic spines. It begins with Santiago Ramón y Cajal, a Spanish professor of Pathology and Histology, and his work entitled Estractura delos centros nerviosos de la aves (Structure of the Nervous Centers in Birds) and how he discovered the spines using the Golgi technique. Cajal defined “spine” on the spines of a rose bush, as it resembled one when he first investigated it in Purkinje cells.
Peter Sterling
- Published in print:
- 2015
- Published Online:
- September 2016
- ISBN:
- 9780262028707
- eISBN:
- 9780262327312
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262028707.003.0014
- Subject:
- Neuroscience, Research and Theory
Learning belongs to a broad principle of biological design: adapt, match, learn, and forget. Organisms respond to changed demands by re-sculpting at all levels to prepare for what will most likely be ...
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Learning belongs to a broad principle of biological design: adapt, match, learn, and forget. Organisms respond to changed demands by re-sculpting at all levels to prepare for what will most likely be next. Physical exercise thickens skin and strengthens muscle; mental practice combined with motor practice refines neural circuits and thereby skills. Circuits at early stages, e.g., V1, re-sculpt to match stable changes in bottom-up statistics. Circuits at later stages can, with extended training and practice, radically rewire. For example, an “object” area can re-wire to recognize and store written symbols and words – as it prunes back circuits that recognize and store objects. Because circuits occupy space in a skull of fixed volume, learning couples inescapably to forgetting. Efficient learning involves all the principles of neural design across all spatial and temporal scales: use chemistry; store only what is needed; store only for as long as needed; store and retrieve information without adding wire. Since learning requires practice, efficient design requires a teaching signal to tell the organism what behaviour to repeat. This is the dopamine reward signal that serves as a final common pathway for many learning systems across the whole brain. A similar circuit operates in insects.Less
Learning belongs to a broad principle of biological design: adapt, match, learn, and forget. Organisms respond to changed demands by re-sculpting at all levels to prepare for what will most likely be next. Physical exercise thickens skin and strengthens muscle; mental practice combined with motor practice refines neural circuits and thereby skills. Circuits at early stages, e.g., V1, re-sculpt to match stable changes in bottom-up statistics. Circuits at later stages can, with extended training and practice, radically rewire. For example, an “object” area can re-wire to recognize and store written symbols and words – as it prunes back circuits that recognize and store objects. Because circuits occupy space in a skull of fixed volume, learning couples inescapably to forgetting. Efficient learning involves all the principles of neural design across all spatial and temporal scales: use chemistry; store only what is needed; store only for as long as needed; store and retrieve information without adding wire. Since learning requires practice, efficient design requires a teaching signal to tell the organism what behaviour to repeat. This is the dopamine reward signal that serves as a final common pathway for many learning systems across the whole brain. A similar circuit operates in insects.
Richard J. Beninger
- Published in print:
- 2018
- Published Online:
- September 2018
- ISBN:
- 9780198824091
- eISBN:
- 9780191862755
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198824091.003.0011
- Subject:
- Neuroscience, Behavioral Neuroscience, Neuroendocrine and Autonomic
Neuroanatomy and dopamine systems explains how sensory signals ascend the central nervous system via a series of nuclei; axons detecting specific elements converge onto higher-order neurons that ...
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Neuroanatomy and dopamine systems explains how sensory signals ascend the central nervous system via a series of nuclei; axons detecting specific elements converge onto higher-order neurons that respond to particular stimulus features. Assemblies of feature-detection cells in the cerebral cortex detect complex stimuli such as faces. These cell assemblies project to motor nuclei of the dorsal and ventral striatum where they terminate on dendritic spines of efferent medium spiny neurons. Dopaminergic projections from ventral mesencephalic nuclei terminate on the same spines. Individual corticostriatal afferents contact relatively few medium spiny neurons and individual dopaminergic neurons contact a far larger number. Stimuli activate specific subsets of corticostriatal synapses. Synaptic activity that is closely followed by a rewarding stimulus, that produces a burst of action potentials in dopaminergic neurons, is modified so that those specific corticostriatal synapses acquire an increased ability to elicit approach and other responses in the future, i.e., incentive learning.Less
Neuroanatomy and dopamine systems explains how sensory signals ascend the central nervous system via a series of nuclei; axons detecting specific elements converge onto higher-order neurons that respond to particular stimulus features. Assemblies of feature-detection cells in the cerebral cortex detect complex stimuli such as faces. These cell assemblies project to motor nuclei of the dorsal and ventral striatum where they terminate on dendritic spines of efferent medium spiny neurons. Dopaminergic projections from ventral mesencephalic nuclei terminate on the same spines. Individual corticostriatal afferents contact relatively few medium spiny neurons and individual dopaminergic neurons contact a far larger number. Stimuli activate specific subsets of corticostriatal synapses. Synaptic activity that is closely followed by a rewarding stimulus, that produces a burst of action potentials in dopaminergic neurons, is modified so that those specific corticostriatal synapses acquire an increased ability to elicit approach and other responses in the future, i.e., incentive learning.
