Jay A. Liveson and Dong M. Ma
- Published in print:
- 1999
- Published Online:
- March 2012
- ISBN:
- 9780195129243
- eISBN:
- 9780199847792
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195129243.003.0011
- Subject:
- Neuroscience, Techniques
It is well known that the sensory cortex responds to peripheral input, and that sensory stimuli evoke a cortical response. In fact, in cases of myoclonic epilepsy, the response to a peripheral ...
More
It is well known that the sensory cortex responds to peripheral input, and that sensory stimuli evoke a cortical response. In fact, in cases of myoclonic epilepsy, the response to a peripheral stimulus can be detected using standard electroencephalogram (EEG ) recording. In normal subjects, however, the responses are of much lower amplitude. The normal EEG activity and the normal “noise” in the recording devices are of high enough voltage to mask any evoked response. With the onset of averaging technology, these small potentials became detectable. The procedure is to time-lock a peripheral stimulus to another which triggers the sweep of a computer of average transients. Any evoked potential that recurs with a fixed relationship to this peripheral stimulus is summed by the computer. All non-related potentials, or random waves, are progressively diminished and eventually cancel out. Thus, with adequate averaging, smaller and smaller evoked potentials can be extracted from the background activity.Less
It is well known that the sensory cortex responds to peripheral input, and that sensory stimuli evoke a cortical response. In fact, in cases of myoclonic epilepsy, the response to a peripheral stimulus can be detected using standard electroencephalogram (EEG ) recording. In normal subjects, however, the responses are of much lower amplitude. The normal EEG activity and the normal “noise” in the recording devices are of high enough voltage to mask any evoked response. With the onset of averaging technology, these small potentials became detectable. The procedure is to time-lock a peripheral stimulus to another which triggers the sweep of a computer of average transients. Any evoked potential that recurs with a fixed relationship to this peripheral stimulus is summed by the computer. All non-related potentials, or random waves, are progressively diminished and eventually cancel out. Thus, with adequate averaging, smaller and smaller evoked potentials can be extracted from the background activity.
Malcolm Burrows
- Published in print:
- 1996
- Published Online:
- March 2012
- ISBN:
- 9780198523444
- eISBN:
- 9780191724411
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198523444.003.0004
- Subject:
- Neuroscience, Invertebrate Neurobiology
A functional nervous system must be laid down embryonically and be capable of producing adaptive movements in response to particular sensory stimuli as soon as the diminutive larval locust emerges ...
More
A functional nervous system must be laid down embryonically and be capable of producing adaptive movements in response to particular sensory stimuli as soon as the diminutive larval locust emerges from the ground. During embryonic development, the majority of central neurons are formed and have established their connections, as have the majority of proprioceptors at the joints. For example, all the motor neurons innervating the leg muscles have formed, all the proprioceptors at the leg joints are in place, and all the peripheral nerve pathways are established. Many exteroceptors are also formed and have established connections in the central nervous system, but others will develop postembryonically as the surface area of the body increases.Less
A functional nervous system must be laid down embryonically and be capable of producing adaptive movements in response to particular sensory stimuli as soon as the diminutive larval locust emerges from the ground. During embryonic development, the majority of central neurons are formed and have established their connections, as have the majority of proprioceptors at the joints. For example, all the motor neurons innervating the leg muscles have formed, all the proprioceptors at the leg joints are in place, and all the peripheral nerve pathways are established. Many exteroceptors are also formed and have established connections in the central nervous system, but others will develop postembryonically as the surface area of the body increases.
G. N. Orlovsky, T. G. Deliagina, and S. Grillner
- Published in print:
- 1999
- Published Online:
- March 2012
- ISBN:
- 9780198524052
- eISBN:
- 9780191724497
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198524052.003.0009
- Subject:
- Neuroscience, Sensory and Motor Systems
This chapter focuses on the swimming characteristics of toads. The toad tadpole presents a unique vertebrate animal model for studying the nervous control of locomotion, and has been used extensively ...
More
This chapter focuses on the swimming characteristics of toads. The toad tadpole presents a unique vertebrate animal model for studying the nervous control of locomotion, and has been used extensively to investigate the spinal mechanisms of undulatory swimming. The main object for studies of the cellular and network mechanisms of undulatory swimming is the embryo of the toad Xenopus laevis. The embryos can swim if released from their egg membrane shortly before they normally hatch. Swimming is due to the waves of lateral body flexion that propagate periodically, at a frequency of 10–25 Hz, from the head towards the tail. Swimming can be evoked as an escape reaction to different sensory stimuli. Swimming in the tadpole is based on caudally propagating periodical waves of lateral body flexions controlled by the spinal cord. In the escape reaction, the spinal central patter generator is activated by sensory input.Less
This chapter focuses on the swimming characteristics of toads. The toad tadpole presents a unique vertebrate animal model for studying the nervous control of locomotion, and has been used extensively to investigate the spinal mechanisms of undulatory swimming. The main object for studies of the cellular and network mechanisms of undulatory swimming is the embryo of the toad Xenopus laevis. The embryos can swim if released from their egg membrane shortly before they normally hatch. Swimming is due to the waves of lateral body flexion that propagate periodically, at a frequency of 10–25 Hz, from the head towards the tail. Swimming can be evoked as an escape reaction to different sensory stimuli. Swimming in the tadpole is based on caudally propagating periodical waves of lateral body flexions controlled by the spinal cord. In the escape reaction, the spinal central patter generator is activated by sensory input.
Reza Shadmehr and Sandro Mussa-Ivaldi
- Published in print:
- 2012
- Published Online:
- August 2013
- ISBN:
- 9780262016964
- eISBN:
- 9780262301282
- Item type:
- book
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262016964.001.0001
- Subject:
- Neuroscience, Research and Theory
This book presents a theoretical framework for understanding the regularity of the brain’s perceptions, its reactions to sensory stimuli, and its control of movements. The book offers an account of ...
More
This book presents a theoretical framework for understanding the regularity of the brain’s perceptions, its reactions to sensory stimuli, and its control of movements. The book offers an account of perception as the combination of prediction and observation: the brain builds internal models that describe what should happen and then combines this prediction with reports from the sensory system to form a belief. Considering the brain’s control of movements, and variations despite biomechanical similarities among old and young, healthy and unhealthy, and humans and other animals, chapters review evidence suggesting that motor commands reflect an economic decision made by our brain weighing reward and effort. This evidence also suggests that the brain prefers to receive a reward sooner than later, devaluing or discounting reward with the passage of time; then as the value of the expected reward changes in the brain with the passing of time (because of development, disease, or evolution), the shape of the movements will also change. The internal models formed by the brain provide it with an essential survival skill: the ability to predict based on past observations. The formal concepts presented by the authors offer a way to describe how representations are formed, what structure they have, and how the theoretical concepts can be tested.Less
This book presents a theoretical framework for understanding the regularity of the brain’s perceptions, its reactions to sensory stimuli, and its control of movements. The book offers an account of perception as the combination of prediction and observation: the brain builds internal models that describe what should happen and then combines this prediction with reports from the sensory system to form a belief. Considering the brain’s control of movements, and variations despite biomechanical similarities among old and young, healthy and unhealthy, and humans and other animals, chapters review evidence suggesting that motor commands reflect an economic decision made by our brain weighing reward and effort. This evidence also suggests that the brain prefers to receive a reward sooner than later, devaluing or discounting reward with the passage of time; then as the value of the expected reward changes in the brain with the passing of time (because of development, disease, or evolution), the shape of the movements will also change. The internal models formed by the brain provide it with an essential survival skill: the ability to predict based on past observations. The formal concepts presented by the authors offer a way to describe how representations are formed, what structure they have, and how the theoretical concepts can be tested.
Catherine Wilson
- Published in print:
- 2017
- Published Online:
- March 2017
- ISBN:
- 9780198779643
- eISBN:
- 9780191824692
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198779643.003.0005
- Subject:
- Philosophy, History of Philosophy
What is a ‘veridical visual experience’? This irreducibly normative notion confusingly suggests a ‘match’ between experiences and an unseen or unperceivable reality. And although the notion of an ...
More
What is a ‘veridical visual experience’? This irreducibly normative notion confusingly suggests a ‘match’ between experiences and an unseen or unperceivable reality. And although the notion of an ‘optical illusion’ appears in technical discussions of the processing of sensory stimuli, it is obvious that natural science cannot supply criteria for veridicality. The Meditations seems to tell us both that all our visual experiences are radically false and that we can trust them as mostly true, but I argue that Descartes grasped the problem of understanding veridicality and provided the framework for a solution, which I develop in this chapter. Two key ideas are required: the notion of a ‘quasinormative’ animal machine whose experiences are not ‘matched’ to the world but to the behavioural outputs it needs to live, and the notion of a circumstantial ‘defeater’ of the organism’s efforts on some occasion.Less
What is a ‘veridical visual experience’? This irreducibly normative notion confusingly suggests a ‘match’ between experiences and an unseen or unperceivable reality. And although the notion of an ‘optical illusion’ appears in technical discussions of the processing of sensory stimuli, it is obvious that natural science cannot supply criteria for veridicality. The Meditations seems to tell us both that all our visual experiences are radically false and that we can trust them as mostly true, but I argue that Descartes grasped the problem of understanding veridicality and provided the framework for a solution, which I develop in this chapter. Two key ideas are required: the notion of a ‘quasinormative’ animal machine whose experiences are not ‘matched’ to the world but to the behavioural outputs it needs to live, and the notion of a circumstantial ‘defeater’ of the organism’s efforts on some occasion.
Reza Shadmehr and Sandro Mussa-Ivaldi
- Published in print:
- 2012
- Published Online:
- August 2013
- ISBN:
- 9780262016964
- eISBN:
- 9780262301282
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262016964.003.0001
- Subject:
- Neuroscience, Research and Theory
This book concentrates on the regularity in how the brain perceives the world, the regularity in how the brain reacts to sensory stimuli, and most crucially, the regularity in how the brain controls ...
More
This book concentrates on the regularity in how the brain perceives the world, the regularity in how the brain reacts to sensory stimuli, and most crucially, the regularity in how the brain controls the movements. It first introduces this regularity and then tries to make sense of it using theory—in particular, theory of the kind that relies on mathematics. It also reports mathematical concepts that relate to the formation of internal models in movement control and perception. In a way, this book is about mathematical models of brain models.Less
This book concentrates on the regularity in how the brain perceives the world, the regularity in how the brain reacts to sensory stimuli, and most crucially, the regularity in how the brain controls the movements. It first introduces this regularity and then tries to make sense of it using theory—in particular, theory of the kind that relies on mathematics. It also reports mathematical concepts that relate to the formation of internal models in movement control and perception. In a way, this book is about mathematical models of brain models.
