Michael Denham - Academia.edu (original) (raw)

Papers by Michael Denham

IJCNN'01. International Joint Conference on Neural Networks. Proceedings (Cat. No.01CH37222)

ABSTRACT

Reviews in the Neurosciences, 1999

The superiority of the human brain in information retrieval (IR) tasks seems to come firstly from... more The superiority of the human brain in information retrieval (IR) tasks seems to come firstly from its ability to read and understand the concepts, ideas or meanings central to documents, in order to reason out the usefulness of documents to information needs, and secondly from its ability to learn from experience and be adaptive to the environment. In this work we attempt to incorporate these properties into the development of an IR model to improve document retrieval. We investigate the applicability of concept lattices, which are based on the theory of Formal Concept Analysis (FCA), to the representation of documents. This allows the use of more elegant representation units, as opposed to keywords, in order to better capture concepts/ideas expressed in natural language text. We also investigate the use of a reinforcement leaming strategy to learn and improve document representations, based on the information present in query statements and user relevance feedback. Features or conc...

Understanding the neocortical neural architecture and circuitry in the brain that subserves our p... more Understanding the neocortical neural architecture and circuitry in the brain that subserves our perceptual and cognitive abilities will be an important component of a “Grand Challenge” which aims at an understanding of the architecture of mind and brain. We have recently embarked on a new five-year collaborative research programme, the primary aim of which is to build a computational model of minimal complexity that captures the fundamental information processing properties of the laminar microcircuitry of the primary visual area of neocortex. Specifically the properties we aim to capture are those of self-organisation, adaptation, and plasticity, which would enable the model to: (i). develop feature selective neuronal properties and cortical preference maps in response to a combination of intrinsic, spontaneously-generated activity and complex naturalistic external stimuli; and (ii) display experience-dependent and adaptation-induced plasticity, which optimally modifies the feature...

1998 Ieee International Joint Conference on Neural Networks Proceedings Ieee World Congress on Computational Intelligence, May 4, 1998

The perception of double vowel stimuli has previously been modelled on the basis of determining t... more The perception of double vowel stimuli has previously been modelled on the basis of determining the pitch of the component sounds, using this information to segregate frequency channels which comprise each of the sounds, and then using a "vowel" template to identify the stimulus. Such models fail to adequately account for the human ability to distinguish vowels with the same fundamental frequency, or the effects of vowel inharmonicity, and have difficulty in explaining the results of experiments using short duration stimuli. The model we describe is based on the connectivity of the thalamocortical system and shows how a competitive recognition process and topdown suppression of the dominant vowel can lead to the identification of both vowels even in the absence of pitch grouping cues. This model provides a novel explanation for the perception of double vowel stimuli and is consistent with results showing the dependence of the phenomenon on stimulus duration.

Major aspects of current research in the field of discrete event control system design are identi... more Major aspects of current research in the field of discrete event control system design are identified, and the requirements for future research, in particular related to CAD methods and tools, are discussed. Existing modelling methods for discrete and hybrid systems are summarised, then the establishment of a control theory and the derivation of controllers is discussed. The properties of hybrid and discrete event models include the ability to model control software directly.

1998 Ieee International Joint Conference on Neural Networks Proceedings Ieee World Congress on Computational Intelligence, May 4, 1998

The auditory system segregates incoming acoustic signals into perceptual representations of sound... more The auditory system segregates incoming acoustic signals into perceptual representations of sound sources within the environment, but how and where this is done is not yet clear. Psychophysical experiments on auditory streaming provide many clues about processing within the auditory system and offer a good basis for the development of models of auditory processing within a simplified paradigm. We propose a physiological basis for the process of primitive streaming, exploring our ideas by means of a computational model of the system. The model provides a novel explanation of the formation of auditory streams, and a basis for the integration of other grouping cues and attention.

The authors research programme has concentrated on two areas: (i) investigation of the dynamic be... more The authors research programme has concentrated on two areas: (i) investigation of the dynamic behaviour of networks composed of arrays of coupled nonlinear differential equations, each equation modelling the leaky integrator shunting dynamics of membrane potential; (ii) the development of an initial outline scheme for a sensory-motor coordination and control system for an intelligent robot based on oscillatory neural networks and synchronous association mechanisms. The authors discuss the background to the research and then present their preliminary results of simulation experiments (synchronised oscillations and chaotic behaviour) and of coordination and control system. >

1991 Proceedings of the 30th Ieee Conference on Decision and Control, Dec 11, 1991

The authors describe some preliminary results on the application of oscillatory neural networks t... more The authors describe some preliminary results on the application of oscillatory neural networks to the coordination and control of nonrhythmic, sensor-induced, free movement in intelligent adaptive industrial robots. In such devices, as appears to be the case in living creatures, sensory stimuli arrive at specific sensors and generate oscillatory space-time neural activity which results in recognition, association, and generation of

1998 Ieee International Joint Conference on Neural Networks Proceedings Ieee World Congress on Computational Intelligence, May 4, 1998

We propose a model of predictive learning in the rat hippocampus which is based on the synaptic p... more We propose a model of predictive learning in the rat hippocampus which is based on the synaptic potentiation of hippocampal pyramidal cells during temporally asymmetric pairing of EPSPs and backpropagating action potentials. The proposal is that potentiation of the synapses that mossy fibre projections of the dentate gyrus make with pyramidal cells in the CA3 region of the hippocampus causes a gradual shift backward in time of the postsynaptic activity of the CA3 cells, the firing of which initially corresponded to the rat being in a particular location. Thus these "place cells" now fire before the rat reaches this location, causing an apparent backward shift in space of the place field of the cell. The model offers both an explanation of this phenomenon which has been observed experimentally, and a possible basis for further understanding of the role of the hippocampus.

Describes a theory and procedure for the analysis and synthesis of supervisory controllers for di... more Describes a theory and procedure for the analysis and synthesis of supervisory controllers for discrete-event systems such as computing, communication and manufacturing systems. The approach described is based on the use of a Petri net model of the discrete-event system. The approach involves the control of the logical behaviour of the system, rather than its control to meet quantitative performance measures. >

1986 25th Ieee Conference on Decision and Control, 1986

This paper considers the problem of devising an adequate theory in which the behaviour of flexibl... more This paper considers the problem of devising an adequate theory in which the behaviour of flexible manufacturing systems, at the level of coordination and control of a set of interacting, communicating concurrent processes, can be modelled and analysed. Existing approaches to a solution are reviewed and the outline of a proposed new approach based on some recent concepts such as object oriented systems is described.

... Centre for Neural and Adaptive Systems, University of Plymouth, UK rohan/mike@soc.plym.ac. uk... more ... Centre for Neural and Adaptive Systems, University of Plymouth, UK rohan/mike@soc.plym.ac. uk ... Amongst are the one proposed by Kosko[15], the originator of BAMs and that proposed byRadim B lohlávek [2]. A real threshold i x ( j y) is assigned to the ith neuron of the first ...

IJCNN'01. International Joint Conference on Neural Networks. Proceedings (Cat. No.01CH37222)

ABSTRACT

Reviews in the Neurosciences, 1999

The superiority of the human brain in information retrieval (IR) tasks seems to come firstly from... more The superiority of the human brain in information retrieval (IR) tasks seems to come firstly from its ability to read and understand the concepts, ideas or meanings central to documents, in order to reason out the usefulness of documents to information needs, and secondly from its ability to learn from experience and be adaptive to the environment. In this work we attempt to incorporate these properties into the development of an IR model to improve document retrieval. We investigate the applicability of concept lattices, which are based on the theory of Formal Concept Analysis (FCA), to the representation of documents. This allows the use of more elegant representation units, as opposed to keywords, in order to better capture concepts/ideas expressed in natural language text. We also investigate the use of a reinforcement leaming strategy to learn and improve document representations, based on the information present in query statements and user relevance feedback. Features or conc...

Understanding the neocortical neural architecture and circuitry in the brain that subserves our p... more Understanding the neocortical neural architecture and circuitry in the brain that subserves our perceptual and cognitive abilities will be an important component of a “Grand Challenge” which aims at an understanding of the architecture of mind and brain. We have recently embarked on a new five-year collaborative research programme, the primary aim of which is to build a computational model of minimal complexity that captures the fundamental information processing properties of the laminar microcircuitry of the primary visual area of neocortex. Specifically the properties we aim to capture are those of self-organisation, adaptation, and plasticity, which would enable the model to: (i). develop feature selective neuronal properties and cortical preference maps in response to a combination of intrinsic, spontaneously-generated activity and complex naturalistic external stimuli; and (ii) display experience-dependent and adaptation-induced plasticity, which optimally modifies the feature...

1998 Ieee International Joint Conference on Neural Networks Proceedings Ieee World Congress on Computational Intelligence, May 4, 1998

The perception of double vowel stimuli has previously been modelled on the basis of determining t... more The perception of double vowel stimuli has previously been modelled on the basis of determining the pitch of the component sounds, using this information to segregate frequency channels which comprise each of the sounds, and then using a "vowel" template to identify the stimulus. Such models fail to adequately account for the human ability to distinguish vowels with the same fundamental frequency, or the effects of vowel inharmonicity, and have difficulty in explaining the results of experiments using short duration stimuli. The model we describe is based on the connectivity of the thalamocortical system and shows how a competitive recognition process and topdown suppression of the dominant vowel can lead to the identification of both vowels even in the absence of pitch grouping cues. This model provides a novel explanation for the perception of double vowel stimuli and is consistent with results showing the dependence of the phenomenon on stimulus duration.

Major aspects of current research in the field of discrete event control system design are identi... more Major aspects of current research in the field of discrete event control system design are identified, and the requirements for future research, in particular related to CAD methods and tools, are discussed. Existing modelling methods for discrete and hybrid systems are summarised, then the establishment of a control theory and the derivation of controllers is discussed. The properties of hybrid and discrete event models include the ability to model control software directly.

1998 Ieee International Joint Conference on Neural Networks Proceedings Ieee World Congress on Computational Intelligence, May 4, 1998

The auditory system segregates incoming acoustic signals into perceptual representations of sound... more The auditory system segregates incoming acoustic signals into perceptual representations of sound sources within the environment, but how and where this is done is not yet clear. Psychophysical experiments on auditory streaming provide many clues about processing within the auditory system and offer a good basis for the development of models of auditory processing within a simplified paradigm. We propose a physiological basis for the process of primitive streaming, exploring our ideas by means of a computational model of the system. The model provides a novel explanation of the formation of auditory streams, and a basis for the integration of other grouping cues and attention.

The authors research programme has concentrated on two areas: (i) investigation of the dynamic be... more The authors research programme has concentrated on two areas: (i) investigation of the dynamic behaviour of networks composed of arrays of coupled nonlinear differential equations, each equation modelling the leaky integrator shunting dynamics of membrane potential; (ii) the development of an initial outline scheme for a sensory-motor coordination and control system for an intelligent robot based on oscillatory neural networks and synchronous association mechanisms. The authors discuss the background to the research and then present their preliminary results of simulation experiments (synchronised oscillations and chaotic behaviour) and of coordination and control system. >

1991 Proceedings of the 30th Ieee Conference on Decision and Control, Dec 11, 1991

The authors describe some preliminary results on the application of oscillatory neural networks t... more The authors describe some preliminary results on the application of oscillatory neural networks to the coordination and control of nonrhythmic, sensor-induced, free movement in intelligent adaptive industrial robots. In such devices, as appears to be the case in living creatures, sensory stimuli arrive at specific sensors and generate oscillatory space-time neural activity which results in recognition, association, and generation of

1998 Ieee International Joint Conference on Neural Networks Proceedings Ieee World Congress on Computational Intelligence, May 4, 1998

We propose a model of predictive learning in the rat hippocampus which is based on the synaptic p... more We propose a model of predictive learning in the rat hippocampus which is based on the synaptic potentiation of hippocampal pyramidal cells during temporally asymmetric pairing of EPSPs and backpropagating action potentials. The proposal is that potentiation of the synapses that mossy fibre projections of the dentate gyrus make with pyramidal cells in the CA3 region of the hippocampus causes a gradual shift backward in time of the postsynaptic activity of the CA3 cells, the firing of which initially corresponded to the rat being in a particular location. Thus these "place cells" now fire before the rat reaches this location, causing an apparent backward shift in space of the place field of the cell. The model offers both an explanation of this phenomenon which has been observed experimentally, and a possible basis for further understanding of the role of the hippocampus.

Describes a theory and procedure for the analysis and synthesis of supervisory controllers for di... more Describes a theory and procedure for the analysis and synthesis of supervisory controllers for discrete-event systems such as computing, communication and manufacturing systems. The approach described is based on the use of a Petri net model of the discrete-event system. The approach involves the control of the logical behaviour of the system, rather than its control to meet quantitative performance measures. >

1986 25th Ieee Conference on Decision and Control, 1986

This paper considers the problem of devising an adequate theory in which the behaviour of flexibl... more This paper considers the problem of devising an adequate theory in which the behaviour of flexible manufacturing systems, at the level of coordination and control of a set of interacting, communicating concurrent processes, can be modelled and analysed. Existing approaches to a solution are reviewed and the outline of a proposed new approach based on some recent concepts such as object oriented systems is described.

... Centre for Neural and Adaptive Systems, University of Plymouth, UK rohan/mike@soc.plym.ac. uk... more ... Centre for Neural and Adaptive Systems, University of Plymouth, UK rohan/mike@soc.plym.ac. uk ... Amongst are the one proposed by Kosko[15], the originator of BAMs and that proposed byRadim B lohlávek [2]. A real threshold i x ( j y) is assigned to the ith neuron of the first ...