Jozien Goense and Nikos K. Logothetis
- Published in print:
- 2010
- Published Online:
- May 2010
- ISBN:
- 9780195372731
- eISBN:
- 9780199776283
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195372731.003.0002
- Subject:
- Neuroscience, Techniques
Functional magnetic resonance imaging (fMRI) and other non-invasive imaging methods have greatly expanded our knowledge of human brain function. Although MRI was invented in the early 1970s and has ...
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Functional magnetic resonance imaging (fMRI) and other non-invasive imaging methods have greatly expanded our knowledge of human brain function. Although MRI was invented in the early 1970s and has been used clinically since the mid-1980s, its use in cognitive neuroscience expanded greatly with the advent of blood oxygenation level dependent (BOLD) functional imaging, and by now, fMRI is a mainstay of neuroscience research. This chapter gives an overview of the relation between the BOLD signal and the underlying neural signals. It focuses on intracortically recorded neural signals, recorded with microelectrodes.Less
Functional magnetic resonance imaging (fMRI) and other non-invasive imaging methods have greatly expanded our knowledge of human brain function. Although MRI was invented in the early 1970s and has been used clinically since the mid-1980s, its use in cognitive neuroscience expanded greatly with the advent of blood oxygenation level dependent (BOLD) functional imaging, and by now, fMRI is a mainstay of neuroscience research. This chapter gives an overview of the relation between the BOLD signal and the underlying neural signals. It focuses on intracortically recorded neural signals, recorded with microelectrodes.
Donald Eugene Canfield
- Published in print:
- 2014
- Published Online:
- October 2017
- ISBN:
- 9780691145020
- eISBN:
- 9781400849888
- Item type:
- book
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691145020.001.0001
- Subject:
- Environmental Science, Climate
The air we breathe is 21 percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? ...
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The air we breathe is 21 percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? This book covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. The book guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, the book takes readers on a remarkable journey through the history of the oxygenation of our planet.Less
The air we breathe is 21 percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? This book covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. The book guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, the book takes readers on a remarkable journey through the history of the oxygenation of our planet.
Donald Eugene Canfield
- Published in print:
- 2014
- Published Online:
- October 2017
- ISBN:
- 9780691145020
- eISBN:
- 9781400849888
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691145020.003.0010
- Subject:
- Environmental Science, Climate
This chapter considers the significance of the Ediacaran Fauna. Until the late 1980s, the Ediacaran Fauna were usually thought to represent ancient, primitive animal forms. Debate was sparked when ...
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This chapter considers the significance of the Ediacaran Fauna. Until the late 1980s, the Ediacaran Fauna were usually thought to represent ancient, primitive animal forms. Debate was sparked when leading paleontologist Dolf Seilacher from Tubingen, Germany, reinterpreted these fossils as something completely different. He argued that, instead of animals, they were long-extinct varieties of living organisms, a result of failed lineages with no successors. The rocks on the Avalon Peninsula of southeastern Newfoundland house the oldest known representatives of the Ediacaran Fauna. These so-called rangeomorphs date back to 575 million ago and appear relatively soon after the end of the Gaskiers glaciation some 580 million years ago. Evidence suggests that Ediacaran Fauna of the Avalon Peninsula emerged into an ocean undergoing oxygenation.Less
This chapter considers the significance of the Ediacaran Fauna. Until the late 1980s, the Ediacaran Fauna were usually thought to represent ancient, primitive animal forms. Debate was sparked when leading paleontologist Dolf Seilacher from Tubingen, Germany, reinterpreted these fossils as something completely different. He argued that, instead of animals, they were long-extinct varieties of living organisms, a result of failed lineages with no successors. The rocks on the Avalon Peninsula of southeastern Newfoundland house the oldest known representatives of the Ediacaran Fauna. These so-called rangeomorphs date back to 575 million ago and appear relatively soon after the end of the Gaskiers glaciation some 580 million years ago. Evidence suggests that Ediacaran Fauna of the Avalon Peninsula emerged into an ocean undergoing oxygenation.
Nikolai Axmacher
- Published in print:
- 2012
- Published Online:
- September 2012
- ISBN:
- 9780199580286
- eISBN:
- 9780191739408
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199580286.003.0021
- Subject:
- Neuroscience, Disorders of the Nervous System, Behavioral Neuroscience
This chapter first summarizes data on the neural correlate of the initial step of declarative memory formation, i.e., of encoding which either leads to a feeling of familiarity or to conscious ...
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This chapter first summarizes data on the neural correlate of the initial step of declarative memory formation, i.e., of encoding which either leads to a feeling of familiarity or to conscious recollection. It summarizes evidence showing that the relationship between the blood oxygenation level-dependent (BOLD) signal (recorded with fMRI) and the underlying neural activity appears to be particularly ambiguous in the medial temporal lobe (MTL); in particular, the BOLD signal does not convey clear information about the level of excitation or inhibition in this brain region. The chapter focuses on electrophysiological recordings in animals and intracranial EEG data from epilepsy patients. It argues that memory formation relies on an inhibitory signal in the medial temporal lobe, which renders hippocampal and neocortical stimulus representations sparser, and on oscillatory activity in the gamma and theta frequency ranges. The second part of the chapter discusses the relationship of these phenomena to epileptiform activity and to memory impairments in epilepsy patients. It gives a brief overview on the neural patterns underlying the second step of memory formation, consolidation. It then describes overlapping neural phenomena during consolidation and epilepsy, such as sharp waves and ripples/fast ripples.Less
This chapter first summarizes data on the neural correlate of the initial step of declarative memory formation, i.e., of encoding which either leads to a feeling of familiarity or to conscious recollection. It summarizes evidence showing that the relationship between the blood oxygenation level-dependent (BOLD) signal (recorded with fMRI) and the underlying neural activity appears to be particularly ambiguous in the medial temporal lobe (MTL); in particular, the BOLD signal does not convey clear information about the level of excitation or inhibition in this brain region. The chapter focuses on electrophysiological recordings in animals and intracranial EEG data from epilepsy patients. It argues that memory formation relies on an inhibitory signal in the medial temporal lobe, which renders hippocampal and neocortical stimulus representations sparser, and on oscillatory activity in the gamma and theta frequency ranges. The second part of the chapter discusses the relationship of these phenomena to epileptiform activity and to memory impairments in epilepsy patients. It gives a brief overview on the neural patterns underlying the second step of memory formation, consolidation. It then describes overlapping neural phenomena during consolidation and epilepsy, such as sharp waves and ripples/fast ripples.
William A. Silverman
- Published in print:
- 1999
- Published Online:
- September 2009
- ISBN:
- 9780192630889
- eISBN:
- 9780191723568
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780192630889.003.0045
- Subject:
- Public Health and Epidemiology, Public Health, Epidemiology
This chapter presents a 1997 commentary on the extracorporeal membrane oxygenation (ECMO) trial for neonates with respiratory failure. The ECMO experiences shows that there are significant national ...
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This chapter presents a 1997 commentary on the extracorporeal membrane oxygenation (ECMO) trial for neonates with respiratory failure. The ECMO experiences shows that there are significant national differences in the factors and dynamics that come into play in the spread of high-cost, high-tech, high-risk modern interventions in medicine. It addresses the question: How can we balance the technical challenge of perfecting hardware for life-support against medicine's humane imperative to avoid needless pain and suffering?Less
This chapter presents a 1997 commentary on the extracorporeal membrane oxygenation (ECMO) trial for neonates with respiratory failure. The ECMO experiences shows that there are significant national differences in the factors and dynamics that come into play in the spread of high-cost, high-tech, high-risk modern interventions in medicine. It addresses the question: How can we balance the technical challenge of perfecting hardware for life-support against medicine's humane imperative to avoid needless pain and suffering?
Paul M. Matthews
- Published in print:
- 2001
- Published Online:
- March 2012
- ISBN:
- 9780192630711
- eISBN:
- 9780191724770
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780192630711.003.0001
- Subject:
- Neuroscience, Techniques
This chapter provides an overview of functional magnetic resonance imaging (fMRI) methods and applications, highlighting key concepts and strategies, and includes the full range of techniques by ...
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This chapter provides an overview of functional magnetic resonance imaging (fMRI) methods and applications, highlighting key concepts and strategies, and includes the full range of techniques by which physiological changes accompanying brain activity are defined. It focuses on the changes in blood oxygenation and flow that have been used for the functional magnetic resonance imaging methods. Direct imaging of the blood flow response using perfusion MRI is also discussed. The study furthermore deals with elegant methods that have been developed and allow an extension of this simple concept for one-dimensional imaging into methods for multi-slice two-dimensional or three-dimensional imaging. It outlines the major issues in statistical analysis for fMRI and addresses ways in which the data can be prepared for analysis to minimize artefacts and maximize sensitivity for the detection of activation changes. Finally, the chapter discusses the various applications of fMRI in neuroscience.Less
This chapter provides an overview of functional magnetic resonance imaging (fMRI) methods and applications, highlighting key concepts and strategies, and includes the full range of techniques by which physiological changes accompanying brain activity are defined. It focuses on the changes in blood oxygenation and flow that have been used for the functional magnetic resonance imaging methods. Direct imaging of the blood flow response using perfusion MRI is also discussed. The study furthermore deals with elegant methods that have been developed and allow an extension of this simple concept for one-dimensional imaging into methods for multi-slice two-dimensional or three-dimensional imaging. It outlines the major issues in statistical analysis for fMRI and addresses ways in which the data can be prepared for analysis to minimize artefacts and maximize sensitivity for the detection of activation changes. Finally, the chapter discusses the various applications of fMRI in neuroscience.
Richard A. Jones, Jason A. Brookes, and Chrit T.W. Moonen
- Published in print:
- 2001
- Published Online:
- March 2012
- ISBN:
- 9780192630711
- eISBN:
- 9780191724770
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780192630711.003.0004
- Subject:
- Neuroscience, Techniques
Brain activation is known to lead to enhanced perfusion which, together with other physiological changes, results in a decreased deoxyhaemoglobin concentration in regions of neuronal activity. This ...
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Brain activation is known to lead to enhanced perfusion which, together with other physiological changes, results in a decreased deoxyhaemoglobin concentration in regions of neuronal activity. This effect is referred to as the blood oxygenation level dependent (BOLD) effect. The main purpose of this chapter is to outline the acquisition methods for ultra-fast BOLD functional magnetic resonance imaging (fMRI). It helps to explain the basics of echo planar imaging and alternative ultra-fast imaging techniques, discusses possible artefacts and pitfalls, and also studies the requirements for BOLD fMRI acquisition methods, focusing on echo planar imaging (EPI). The chapter discusses the two basic types of spin echo sequences that have been employed for fMRI studies, namely multiple echo sequences and spin echo EPI. The methods discussed traverse k-space in a rectilinear fashion. Moreover, the chapter also describes promising recent developments and mentions that ultra-fast 3D methods are under development which will potentially provide better signal-to-noise ratio and BOLD contrast per unit time than EPI, and which are also less sensitive to inflow effects.Less
Brain activation is known to lead to enhanced perfusion which, together with other physiological changes, results in a decreased deoxyhaemoglobin concentration in regions of neuronal activity. This effect is referred to as the blood oxygenation level dependent (BOLD) effect. The main purpose of this chapter is to outline the acquisition methods for ultra-fast BOLD functional magnetic resonance imaging (fMRI). It helps to explain the basics of echo planar imaging and alternative ultra-fast imaging techniques, discusses possible artefacts and pitfalls, and also studies the requirements for BOLD fMRI acquisition methods, focusing on echo planar imaging (EPI). The chapter discusses the two basic types of spin echo sequences that have been employed for fMRI studies, namely multiple echo sequences and spin echo EPI. The methods discussed traverse k-space in a rectilinear fashion. Moreover, the chapter also describes promising recent developments and mentions that ultra-fast 3D methods are under development which will potentially provide better signal-to-noise ratio and BOLD contrast per unit time than EPI, and which are also less sensitive to inflow effects.
Jon F. Harrison, H. Arthur Woods, and Stephen P. Roberts
- Published in print:
- 2012
- Published Online:
- December 2013
- ISBN:
- 9780199225941
- eISBN:
- 9780191774607
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199225941.003.0006
- Subject:
- Biology, Animal Biology, Ecology
This chapter talks about the central insect respiratory problem – their capability of regulating oxygen delivery to tissues under variable internal and external conditions – pinpointing in particular ...
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This chapter talks about the central insect respiratory problem – their capability of regulating oxygen delivery to tissues under variable internal and external conditions – pinpointing in particular which physiological mechanisms insects use to regulate oxygen, and how their bodies do so. It also covers the consequences of oxygen deprivation and of oxygen surplus, taking into account a few selected topics that highlight recent progress, rather than aiming for an encyclopedic scope of the subject. The first part of the chapter narrows in on the problems of tissue hypoxia, which is when insects encounter a decreased supply of oxygen. Oftentimes, the reason that tissue oxygenation turns problematic is because there is gross mismatch between supply and demand. This insufficient tissue oxygenation often occurs when an insect transitions from rest to vigorous activity, or when their environment itself contains a decreased supply of oxygen.Less
This chapter talks about the central insect respiratory problem – their capability of regulating oxygen delivery to tissues under variable internal and external conditions – pinpointing in particular which physiological mechanisms insects use to regulate oxygen, and how their bodies do so. It also covers the consequences of oxygen deprivation and of oxygen surplus, taking into account a few selected topics that highlight recent progress, rather than aiming for an encyclopedic scope of the subject. The first part of the chapter narrows in on the problems of tissue hypoxia, which is when insects encounter a decreased supply of oxygen. Oftentimes, the reason that tissue oxygenation turns problematic is because there is gross mismatch between supply and demand. This insufficient tissue oxygenation often occurs when an insect transitions from rest to vigorous activity, or when their environment itself contains a decreased supply of oxygen.
