John Milton - Academia.edu (original) (raw)
Papers by John Milton
Conference Proceedings., IEEE International Conference on Systems, Man and Cybernetics
World Congress of Nonlinear Analysts '92, 1996
ABSTRACT Nonlinear second-order differential equations with delayed displacement dependent feedba... more ABSTRACT Nonlinear second-order differential equations with delayed displacement dependent feedback arise in the setting of the control of neuro-muscular systems with electronic feedback. Here we examine the dynamics of such models of physiological parameter ranges using local stability analysis and computer simulations. The results are discussed with respect to two types of delayed feedback: 1) negative, and 2) “mixed”.
Epilepsy as a Dynamic Disease, 2003
ABSTRACT A seizure involves the synchronization of the activity of a very large population of per... more ABSTRACT A seizure involves the synchronization of the activity of a very large population of periodically firing neurons [4,483]. It is well known that periodic electrical or sensory stimulation can be used to trigger the onset of a seizure. Here we discuss the use of periodic stimuli to abort seizures once they are occurring.
2008 47th IEEE Conference on Decision and Control, 2008
The detection of transient responses, i.e. nonstationarities, that arise in a varying and small f... more The detection of transient responses, i.e. nonstationarities, that arise in a varying and small fraction of the total number of neural spike trains recorded from chronically implanted multielectrode grids becomes increasingly difficult as the number of electrodes grows. This paper presents a novel application of an unsupervised neural network for clustering neural spike trains with transient responses. This network is constructed by incorporating projective clustering into an adaptive resonance type neural network (ART) architecture resulting in a PART neural network. Since comparisons are made between inputs and learned patterns using only a subset of the total number of available dimensions, PART neural networks are ideally suited to the detection of transients. We show that PART neural networks are an effective tool for clustering neural spike trains that is easily implemented, computationally inexpensive, and well suited for detecting neural responses to dynamic environmental stimuli.
Understanding Complex Systems, 2007
... represented a state of “hypersynchrony”, ie synchronous activity in a very large popu-lation ... more ... represented a state of “hypersynchrony”, ie synchronous activity in a very large popu-lation of neurons (Penfield and Jasper 1954 ... Theoretical (Lasota and Mackey 1994; Milton and Mackey 2000) and experimental (Cole 1991) investigations have shown that it is possible for the ...
Electroencephalography and Clinical Neurophysiology, 1995
Human electrocorticographic findings recorded from subdural arrays of electrodes were topographic... more Human electrocorticographic findings recorded from subdural arrays of electrodes were topographically mapped directly onto magnetic resonance images of gyral anatomy. With this technique gyri involved in generating somatosensory evoked potentials and epileptic phenomena are easily identified. Regions of the cortex which exhibit local spectral changes associated with cognitive tasks can also be visualized. These composite images of structure and function can provide insight regarding the functional organization of human cortex in relation to gyral anatomy and localized pathologic rhythms.
Physical Review E, 1997
The multistability that arises in delayed feedback control mechanisms has applications for dynami... more The multistability that arises in delayed feedback control mechanisms has applications for dynamic short term memory storage. Here we investigate the effects of multiplicative, Gaussian-distributed white noise on an integrate-and-fire model of a recurrent inhibitory neural loop: when the neuron fires an inhibitory pulse decreases the membrane potential by an amount ⌬ at time later. For appropriate choices of and ⌬, multistability occurs in the form of qualitatively different neuron firing patterns. In the absence of noise, the number and nature of the coexistent attractors can be precisely determined. When noise is added to ⌬, noise-induced transitions occur between the attractors. The mechanism for these transitions is characterized and it is shown that the rate of transitions has a nonexponential dependence on the noise variance. An electronic circuit is constructed to assess the impact of noise on memory storage. ͓S1063-651X͑97͒08404-3͔
Physica D: Nonlinear Phenomena, 1995
Sufficient conditions for the asymptotic stability (strong convergence) of density evolution in f... more Sufficient conditions for the asymptotic stability (strong convergence) of density evolution in finite dimensional piecewise monotone map lattices with both constant and state dependent coupling are given. These conditions are quite useful in numerical work since they allow one to precisely define where one expects to see numerical signatures of asymptotic stability. Asymptotic stability is illustrated with several examples. It is also shown that in constantly coupled lattices the density formed by collapsing the higher dimensional density into one dimension can be approximated by the evolution of densities under the action of an appropriately perturbed one-dimensional map.
Physica D: Nonlinear Phenomena, 1995
This paper investigates the statistical properties of networks of chaotic elements modeled by cou... more This paper investigates the statistical properties of networks of chaotic elements modeled by coupled map lattices. Transitions separating statistically stable and periodic phases are numerically observed in generic models of excitable media. Similar transitions are studied analytically in lattices of piecewise expanding maps by considering the spectral properties of the Perron-Frobenius operator using the theory of functions of bounded variation in ~".
NeuroImage, 2007
Extraordinary motor skills required for expert athletic or music performance require longstanding... more Extraordinary motor skills required for expert athletic or music performance require longstanding and intensive practice leading to two critical skills, a level of maximal performance that far exceeds that of non-experts and a degree of privileged focus on motor performance that excludes intrusions. This study of motor planning in expert golfers demonstrated their brain activation during their pre-shot routine to be radically different than in novices. The posterior cingulate, the amygdala-forebrain complex, and the basal ganglia were active only in novices, whereas experts had activation primarily in the superior parietal lobule, the dorsal lateral premotor area, and the occipital area. The fact that these differences are apparent before the golfer swings the club suggests that the disparity between the quality of the performance of novice and expert golfers lies at the level of the organization of neural networks during motor planning. In particular, we suggest that extensive practice over a long period of time leads experts to develop a focused and efficient organization of task-related neural networks, whereas novices have difficulty filtering out irrelevant information.
Neural Computation, 2011
We develop a new neural network architecture for projective clustering of data sets that incorpor... more We develop a new neural network architecture for projective clustering of data sets that incorporates adaptive transmission delays and signal transmission information loss. The resultant selective output signaling mechanism does not require the addition of multiple hidden layers but instead is based on the assumption that the signal transmission velocity between input processing neurons and clustering neurons is proportional to the similarity between the input pattern and the feature vector (the top-down weights) of the clustering neuron. The mathematical model governing the evolution of the signal transmission delay, the short-term memory traces, and the long-term memory traces represents a new class of large-scale delay differential equations where the evolution of the delay is described by a nonlinear differential equation involving the similarity measure already noted. We give a complete description of the computational performance of the network for a wide range of parameter va...
Nature, 2008
DNA sequence information underpins genetic research, enabling discoveries of important biological... more DNA sequence information underpins genetic research, enabling discoveries of important biological or medical benefit. Sequencing projects have traditionally used long (400-800 base pair) reads, but the existence of reference sequences for the human and many other genomes makes it possible to develop new, fast approaches to re-sequencing, whereby shorter reads are compared to a reference to identify intraspecies genetic variation. Here we report an approach that generates several billion bases of accurate nucleotide sequence per experiment at low cost. Single molecules of DNA are attached to a flat surface, amplified in situ and used as templates for synthetic sequencing with fluorescent reversible terminator deoxyribonucleotides. Images of the surface are analysed to generate high-quality sequence. We demonstrate application of this approach to human genome sequencing on flow-sorted X chromosomes and then scale the approach to determine the genome sequence of a male Yoruba from Ibadan, Nigeria. We build an accurate consensus sequence from .303 average depth of paired 35-base reads. We characterize four million single-nucleotide polymorphisms and four hundred thousand structural variants, many of which were previously unknown. Our approach is effective for accurate, rapid and economical whole-genome re-sequencing and many other biomedical applications.
Nature, 2003
Elderly but healthy people are often seriously injured in falls. Exploiting the phenomenon of sto... more Elderly but healthy people are often seriously injured in falls. Exploiting the phenomenon of stochastic resonance, biological physicists have designed a shoe with a vibrating insole that helps maintain balance.
The Modern Language Review, 1958
Mathematical Modelling of Natural Phenomena, 2011
The question, how does an organism maintain balance? provides a unifying theme to introduce under... more The question, how does an organism maintain balance? provides a unifying theme to introduce undergraduate students to the use of mathematics and modeling techniques in biological research. The availability of inexpensive high speed motion capture cameras makes it possible to collect the precise and reliable data that facilitates the development of relevant mathematical models. An in-house laboratory component ensures that students have the opportunity to directly compare prediction to observation and motivates the development of projects that push the boundaries of the subject. The projects, by their nature, readily lend themselves to the formation of inter-disciplinary student research teams. Thus students have the opportunity to learn skills essential for success in today's workplace including productive team work, critical thinking, problem solving, project management, and effective communication.
Journal of Proteomics, 2014
Seasonal weight loss is the main limitation to animal production worldwide, significantly affecti... more Seasonal weight loss is the main limitation to animal production worldwide, significantly affecting the productivity of milk, meat and wool farms, particularly in drought-prone areas of the world where most of the large-scale wool production farms are located. Although the effect of nutritional status on wool quality parameters has been extensively studied, little is known on how it affects wool protein composition. Here, a proteomic approach has been applied to study changes in fiber structure and protein composition in wool from merino sheep subjected to experimentally induced weight loss. Results indicate that there is a significant reduction in the fiber diameter of wool from the animals on a restricted diet over a 42-day period. At the same time, significant increases in the expression of the high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family in the wools from the animals on the restricted diet were also detected. Such findings have strong implications for the wool industry that favors finer wool. Seasonal weight loss caused by poor pasture availability has strong effects on wool productivity parameters and quality traits. In this work we determine that experimentally induced weight loss causes a decrease in fiber diameter associated with an increase in the level of high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family. The implication of this is that decreasing the fiber diameter of the wool by this process could result in a fiber reduced prickle but with reduced wearability and appearance retention.
Journal of Physiology-Paris, 2000
Statistical periodicity is a statistical property of densities which arises in the description of... more Statistical periodicity is a statistical property of densities which arises in the description of retarded dynamical systems. This property is particularly attractive as a possible mechanism for the ensemble coding of information in the nervous system because it operates rapidly and has high storage capacity. For a population of neurons which exhibits statistical periodicity, information would not be encoded by the periodicity, but rather by the spatio-temporal distributions of neural activity. Statistical periodicity is discussed in relation to the temporal binding hypothesis and to the occurrence of multistability in neural systems. © 2000 É ditions scientifiques et médicales Elsevier SAS coding / ensemble / densities / statistical periodicity
Conference Proceedings., IEEE International Conference on Systems, Man and Cybernetics
World Congress of Nonlinear Analysts '92, 1996
ABSTRACT Nonlinear second-order differential equations with delayed displacement dependent feedba... more ABSTRACT Nonlinear second-order differential equations with delayed displacement dependent feedback arise in the setting of the control of neuro-muscular systems with electronic feedback. Here we examine the dynamics of such models of physiological parameter ranges using local stability analysis and computer simulations. The results are discussed with respect to two types of delayed feedback: 1) negative, and 2) “mixed”.
Epilepsy as a Dynamic Disease, 2003
ABSTRACT A seizure involves the synchronization of the activity of a very large population of per... more ABSTRACT A seizure involves the synchronization of the activity of a very large population of periodically firing neurons [4,483]. It is well known that periodic electrical or sensory stimulation can be used to trigger the onset of a seizure. Here we discuss the use of periodic stimuli to abort seizures once they are occurring.
2008 47th IEEE Conference on Decision and Control, 2008
The detection of transient responses, i.e. nonstationarities, that arise in a varying and small f... more The detection of transient responses, i.e. nonstationarities, that arise in a varying and small fraction of the total number of neural spike trains recorded from chronically implanted multielectrode grids becomes increasingly difficult as the number of electrodes grows. This paper presents a novel application of an unsupervised neural network for clustering neural spike trains with transient responses. This network is constructed by incorporating projective clustering into an adaptive resonance type neural network (ART) architecture resulting in a PART neural network. Since comparisons are made between inputs and learned patterns using only a subset of the total number of available dimensions, PART neural networks are ideally suited to the detection of transients. We show that PART neural networks are an effective tool for clustering neural spike trains that is easily implemented, computationally inexpensive, and well suited for detecting neural responses to dynamic environmental stimuli.
Understanding Complex Systems, 2007
... represented a state of “hypersynchrony”, ie synchronous activity in a very large popu-lation ... more ... represented a state of “hypersynchrony”, ie synchronous activity in a very large popu-lation of neurons (Penfield and Jasper 1954 ... Theoretical (Lasota and Mackey 1994; Milton and Mackey 2000) and experimental (Cole 1991) investigations have shown that it is possible for the ...
Electroencephalography and Clinical Neurophysiology, 1995
Human electrocorticographic findings recorded from subdural arrays of electrodes were topographic... more Human electrocorticographic findings recorded from subdural arrays of electrodes were topographically mapped directly onto magnetic resonance images of gyral anatomy. With this technique gyri involved in generating somatosensory evoked potentials and epileptic phenomena are easily identified. Regions of the cortex which exhibit local spectral changes associated with cognitive tasks can also be visualized. These composite images of structure and function can provide insight regarding the functional organization of human cortex in relation to gyral anatomy and localized pathologic rhythms.
Physical Review E, 1997
The multistability that arises in delayed feedback control mechanisms has applications for dynami... more The multistability that arises in delayed feedback control mechanisms has applications for dynamic short term memory storage. Here we investigate the effects of multiplicative, Gaussian-distributed white noise on an integrate-and-fire model of a recurrent inhibitory neural loop: when the neuron fires an inhibitory pulse decreases the membrane potential by an amount ⌬ at time later. For appropriate choices of and ⌬, multistability occurs in the form of qualitatively different neuron firing patterns. In the absence of noise, the number and nature of the coexistent attractors can be precisely determined. When noise is added to ⌬, noise-induced transitions occur between the attractors. The mechanism for these transitions is characterized and it is shown that the rate of transitions has a nonexponential dependence on the noise variance. An electronic circuit is constructed to assess the impact of noise on memory storage. ͓S1063-651X͑97͒08404-3͔
Physica D: Nonlinear Phenomena, 1995
Sufficient conditions for the asymptotic stability (strong convergence) of density evolution in f... more Sufficient conditions for the asymptotic stability (strong convergence) of density evolution in finite dimensional piecewise monotone map lattices with both constant and state dependent coupling are given. These conditions are quite useful in numerical work since they allow one to precisely define where one expects to see numerical signatures of asymptotic stability. Asymptotic stability is illustrated with several examples. It is also shown that in constantly coupled lattices the density formed by collapsing the higher dimensional density into one dimension can be approximated by the evolution of densities under the action of an appropriately perturbed one-dimensional map.
Physica D: Nonlinear Phenomena, 1995
This paper investigates the statistical properties of networks of chaotic elements modeled by cou... more This paper investigates the statistical properties of networks of chaotic elements modeled by coupled map lattices. Transitions separating statistically stable and periodic phases are numerically observed in generic models of excitable media. Similar transitions are studied analytically in lattices of piecewise expanding maps by considering the spectral properties of the Perron-Frobenius operator using the theory of functions of bounded variation in ~".
NeuroImage, 2007
Extraordinary motor skills required for expert athletic or music performance require longstanding... more Extraordinary motor skills required for expert athletic or music performance require longstanding and intensive practice leading to two critical skills, a level of maximal performance that far exceeds that of non-experts and a degree of privileged focus on motor performance that excludes intrusions. This study of motor planning in expert golfers demonstrated their brain activation during their pre-shot routine to be radically different than in novices. The posterior cingulate, the amygdala-forebrain complex, and the basal ganglia were active only in novices, whereas experts had activation primarily in the superior parietal lobule, the dorsal lateral premotor area, and the occipital area. The fact that these differences are apparent before the golfer swings the club suggests that the disparity between the quality of the performance of novice and expert golfers lies at the level of the organization of neural networks during motor planning. In particular, we suggest that extensive practice over a long period of time leads experts to develop a focused and efficient organization of task-related neural networks, whereas novices have difficulty filtering out irrelevant information.
Neural Computation, 2011
We develop a new neural network architecture for projective clustering of data sets that incorpor... more We develop a new neural network architecture for projective clustering of data sets that incorporates adaptive transmission delays and signal transmission information loss. The resultant selective output signaling mechanism does not require the addition of multiple hidden layers but instead is based on the assumption that the signal transmission velocity between input processing neurons and clustering neurons is proportional to the similarity between the input pattern and the feature vector (the top-down weights) of the clustering neuron. The mathematical model governing the evolution of the signal transmission delay, the short-term memory traces, and the long-term memory traces represents a new class of large-scale delay differential equations where the evolution of the delay is described by a nonlinear differential equation involving the similarity measure already noted. We give a complete description of the computational performance of the network for a wide range of parameter va...
Nature, 2008
DNA sequence information underpins genetic research, enabling discoveries of important biological... more DNA sequence information underpins genetic research, enabling discoveries of important biological or medical benefit. Sequencing projects have traditionally used long (400-800 base pair) reads, but the existence of reference sequences for the human and many other genomes makes it possible to develop new, fast approaches to re-sequencing, whereby shorter reads are compared to a reference to identify intraspecies genetic variation. Here we report an approach that generates several billion bases of accurate nucleotide sequence per experiment at low cost. Single molecules of DNA are attached to a flat surface, amplified in situ and used as templates for synthetic sequencing with fluorescent reversible terminator deoxyribonucleotides. Images of the surface are analysed to generate high-quality sequence. We demonstrate application of this approach to human genome sequencing on flow-sorted X chromosomes and then scale the approach to determine the genome sequence of a male Yoruba from Ibadan, Nigeria. We build an accurate consensus sequence from .303 average depth of paired 35-base reads. We characterize four million single-nucleotide polymorphisms and four hundred thousand structural variants, many of which were previously unknown. Our approach is effective for accurate, rapid and economical whole-genome re-sequencing and many other biomedical applications.
Nature, 2003
Elderly but healthy people are often seriously injured in falls. Exploiting the phenomenon of sto... more Elderly but healthy people are often seriously injured in falls. Exploiting the phenomenon of stochastic resonance, biological physicists have designed a shoe with a vibrating insole that helps maintain balance.
The Modern Language Review, 1958
Mathematical Modelling of Natural Phenomena, 2011
The question, how does an organism maintain balance? provides a unifying theme to introduce under... more The question, how does an organism maintain balance? provides a unifying theme to introduce undergraduate students to the use of mathematics and modeling techniques in biological research. The availability of inexpensive high speed motion capture cameras makes it possible to collect the precise and reliable data that facilitates the development of relevant mathematical models. An in-house laboratory component ensures that students have the opportunity to directly compare prediction to observation and motivates the development of projects that push the boundaries of the subject. The projects, by their nature, readily lend themselves to the formation of inter-disciplinary student research teams. Thus students have the opportunity to learn skills essential for success in today's workplace including productive team work, critical thinking, problem solving, project management, and effective communication.
Journal of Proteomics, 2014
Seasonal weight loss is the main limitation to animal production worldwide, significantly affecti... more Seasonal weight loss is the main limitation to animal production worldwide, significantly affecting the productivity of milk, meat and wool farms, particularly in drought-prone areas of the world where most of the large-scale wool production farms are located. Although the effect of nutritional status on wool quality parameters has been extensively studied, little is known on how it affects wool protein composition. Here, a proteomic approach has been applied to study changes in fiber structure and protein composition in wool from merino sheep subjected to experimentally induced weight loss. Results indicate that there is a significant reduction in the fiber diameter of wool from the animals on a restricted diet over a 42-day period. At the same time, significant increases in the expression of the high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family in the wools from the animals on the restricted diet were also detected. Such findings have strong implications for the wool industry that favors finer wool. Seasonal weight loss caused by poor pasture availability has strong effects on wool productivity parameters and quality traits. In this work we determine that experimentally induced weight loss causes a decrease in fiber diameter associated with an increase in the level of high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family. The implication of this is that decreasing the fiber diameter of the wool by this process could result in a fiber reduced prickle but with reduced wearability and appearance retention.
Journal of Physiology-Paris, 2000
Statistical periodicity is a statistical property of densities which arises in the description of... more Statistical periodicity is a statistical property of densities which arises in the description of retarded dynamical systems. This property is particularly attractive as a possible mechanism for the ensemble coding of information in the nervous system because it operates rapidly and has high storage capacity. For a population of neurons which exhibits statistical periodicity, information would not be encoded by the periodicity, but rather by the spatio-temporal distributions of neural activity. Statistical periodicity is discussed in relation to the temporal binding hypothesis and to the occurrence of multistability in neural systems. © 2000 É ditions scientifiques et médicales Elsevier SAS coding / ensemble / densities / statistical periodicity