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31
Dynamic field theory of movement preparation
- PSYCHOL REV 109:545–572
, 2002
"... A theoretical framework for understanding movement preparation is proposed. Movement parameters are represented by activation fields, distributions of activation defined over metric spaces. The fields evolve under the influence of various sources of localized input, representing information about up ..."
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Cited by 141 (14 self)
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A theoretical framework for understanding movement preparation is proposed. Movement parameters are represented by activation fields, distributions of activation defined over metric spaces. The fields evolve under the influence of various sources of localized input, representing information about upcoming movements. Localized patterns of activation self-stabilize through cooperative and competitive interactions within the fields. The task environment is represented by a 2nd class of fields, which preshape the movement parameter representation. The model accounts for a sizable body of empirical findings on movement initiation (continuous and graded nature of movement preparation, dependence on the metrics of the task, stimulus uncertainty effect, stimulus–response compatibility effects, Simon effect, precuing paradigm, and others) and suggests new ways of exploring the structure of motor representations.
Testing the dynamic field theory: Working memory for locations becomes more spatially precise over development
- CHILD DEVELOPMENT
, 2003
"... The dynamic field theory predicts that biases toward remembered locations depend on the separation between targets, and the spatial precision of interactions in working memory that become enhanced over development. This was tested by varying the separation between A and B locations in a sandbox. Chi ..."
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Cited by 45 (14 self)
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The dynamic field theory predicts that biases toward remembered locations depend on the separation between targets, and the spatial precision of interactions in working memory that become enhanced over development. This was tested by varying the separation between A and B locations in a sandbox. Children searched for an object 6 times at an A location, followed by 3 trials at a B location. Two- and 4-year-olds’, but not 6-year-olds’, responses were biased toward A when A and B were 9-in. and 6-in. apart. When A and B were separated by 2 in., however, 4- and 6-year-olds’ responses were biased toward A. Thus, the separation at which responses were biased toward A decreased across age groups, supporting the predictions of the theory.
Connectionism and dynamic systems: are they really different?
, 2003
"... We propose that connectionism and dynamic systems theory are strong contenders for a general theory of development that holds true whatever the content domain. We illustrate, through our own career narratives, the origins of these theories in motor and language development. We situate connectionism ..."
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Cited by 28 (0 self)
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We propose that connectionism and dynamic systems theory are strong contenders for a general theory of development that holds true whatever the content domain. We illustrate, through our own career narratives, the origins of these theories in motor and language development. We situate connectionism and dynamic systems among other classic and contemporary theories and conclude that, although there are meaningful differences, these differences pale in relation to the shared assumptions about the fundamental processes and mechanisms of change.
Dynamical changes and temporal precision of synchronised spiking activity in monkey motor cortex during movement preparation
- Journal of Physiology
, 2000
"... Abstract -Movement preparation is considered to be based on central processes which are responsible for improving motor performance. For instance, it has been shown that motor cortical neurones change their activity selectively in relation to prior information about movement parameters. However, it ..."
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Cited by 23 (6 self)
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Abstract -Movement preparation is considered to be based on central processes which are responsible for improving motor performance. For instance, it has been shown that motor cortical neurones change their activity selectively in relation to prior information about movement parameters. However, it is not clear how groups of neurones dynamically organize their activity to cope with computational demands. The aim of the study was to compare the firing rate of multiple simultaneously recorded neurones with the interaction between them by describing not only the frequency of occurrence of epochs of significant synchronization, but also its modulation in time and its changes in temporal precision during an instructed delay. Multiple single-neurone activity was thus recorded in monkey motor cortex during the performance of two different delayed multi-directional pointing tasks. In order to detect conspicuous spike coincidences in simultaneously recorded spike trains by tolerating temporal jitter ranging from 0 to 20 ms and to calculate their statistical significance, a modified method of the 'Unitary Events' analysis was used. Two main results were obtained. First, simultaneously recorded neurones synchronize their spiking activity in a highly dynamic way. Synchronization becomes significant only during short periods (about 100 to 200 ms). Several such periods occurred during a behavioural trial more or less regularly. Second, in many pairs of neurones, the temporal precision of synchronous activity was highest at the end of the preparatory period. As a matter of fact, at the beginning of this period, after the presentation of the preparatory signal, neurones significantly synchronize their spiking activity, but with low temporal precision. As time advances, significant synchronization becomes more precise. Data indicate that not only the discharge rate is involved in preparatory processes, but also temporal aspects of neuronal activity as expressed in the precise synchronization of individual action potentials. © 2000 É ditions scientifiques et médicales Elsevier SAS monkey / motor cortex / multiple single-neurone recordings / precise spike coincidences / cell assemblies
Multiple movement representations in the human brain: an event-related fMRI study
- J. Cogn. Neurosci
, 2002
"... & Neurovascular correlates of response preparation have been investigated in human neuroimaging studies. However, conventional neuroimaging cannot distinguish, within the same trial, between areas involved in response selection and/ or response execution and areas specifically involved in respon ..."
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Cited by 21 (5 self)
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& Neurovascular correlates of response preparation have been investigated in human neuroimaging studies. However, conventional neuroimaging cannot distinguish, within the same trial, between areas involved in response selection and/ or response execution and areas specifically involved in response preparation. The specific contribution of parietal and frontal areas to motor preparation has been explored in electrophysiological studies in monkey. However, the asso-ciative nature of sensorimotor tasks calls for the additional contributions of other cortical regions. In this article, we have investigated the functional anatomy of movement represen-tations in the context of an associative visuomotor task with instructed delays. Neural correlates of movement representa-tions have been assessed by isolating preparatory activity that
Distributional population codes and multiple motion models
- In Advances in Neural Information Processing Systems 11
, 1999
"... Most theoretical and empirical studies of population codes make the assumption that underlying neuronal activities is a unique and unambiguous value of an encoded quantity. However, population activities can contain additional information about such things as multiple values of or uncertainty about ..."
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Cited by 19 (3 self)
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Most theoretical and empirical studies of population codes make the assumption that underlying neuronal activities is a unique and unambiguous value of an encoded quantity. However, population activities can contain additional information about such things as multiple values of or uncertainty about the quantity. We have previously suggested a method to recover extra information by treating the activities of the population of cells as coding for a complete distribution over the coded quantity rather than just a single value. We now show how this approach bears on psychophysical and neurophysiological studies of population codes for motion direction in tasks involving transparent motion stimuli. We show that, unlike standard approaches, it is able to recover multiple motions from population responses, and also that its output is consistent with both correct and erroneous human performance on psychophysical tasks. A population code can be defined as a set of units whose activities collectively encode some underlying variable (or variables). The standard view is that population codes are useful for accurately encoding the underlying variable when the individual units are noisy. Current statistical approaches to interpreting population activity reflect this view, in that they determine the optimal single value that explains the observed activity pattern given a particular model of the noise (and possibly a loss function). In our work, we have pursued an alternative hypothesis, that the population encodes additional information about the underlying variable, including multiple values and uncertainty. The Distributional Population Coding (DPC) framework finds the best probability distribution across values that fits the population activity
A dynamic neural field model of visual working memory and change detection
- Psychological Science
"... A dynamic neural field model of visual working memory and change detection ..."
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Cited by 16 (6 self)
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A dynamic neural field model of visual working memory and change detection
Preparation for action: one of the key functions of the motor cortex
- In Riehle, A. & Vaadia, E. (Eds), Motor Cortex in Voluntary Movements: a Distributed System for Distributed Functions, CRC-Press, Boca Raton, FL
, 2005
"... One of the most striking processes involved in motor behavior is preparation for action. It is considered to be based on central processes, which are responsible for the maximally efficient organization of motor performance. A strong argument in favor of such an efficiency hypothesis of preparatory ..."
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Cited by 9 (0 self)
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One of the most striking processes involved in motor behavior is preparation for action. It is considered to be based on central processes, which are responsible for the maximally efficient organization of motor performance. A strong argument in favor of such an efficiency hypothesis of preparatory processes is the fact that providing prior information about movement parameters and/or removing time uncertainty about when to move significantly shortens reaction time. In this chapter, I will briefly summarize the behavioral effects of prior information and then describe some underlying neuronal correlates encountered in motor cortical areas of behaving monkeys. The types of changes in neuronal activity and their selectivity during preparation will be portrayed and compared with other cortical areas, which are involved in motor behavior. Furthermore, by linking motor cortical activity directly to behavioral performance, the trial-by-trial correlation between single neuron firing rate and reaction time revealed strong task-related cortical dynamics. Finally, the cooperative interplay among neurons, expressed by precise synchronization of their action potentials, will be illustrated and compared with changes in firing rate of the same neurons. New concepts including the notion of coordinated ensemble activity and their functional implication during movement preparation will be discussed.
Cortical Belief Networks
"... Most theoretical and empirical studies of cortical population codes make the assumption that underlying neuronal activities is a unique and unambiguous value of an encoded quantity. We propose an alternative hypothesis, that neural populations represent, and effectively compute probabilities. Und ..."
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Cited by 8 (0 self)
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Most theoretical and empirical studies of cortical population codes make the assumption that underlying neuronal activities is a unique and unambiguous value of an encoded quantity. We propose an alternative hypothesis, that neural populations represent, and effectively compute probabilities. Under this hypothesis, population activities can contain additional information about such things as multiple values of or uncertainty about the quantity. We discuss methods for recovering this extra information, and show how this approach bears on psychophysical and neurophysiological studies. A natural extension of this probabilistic interpretation hypothesis casts interacting populations as a belief network, a structure which permits the analysis of information propagation from one population to another. This novel framework for population codes opens up new avenues for studying a diverse set of problems, including cue combination, decision-making, and visual attention. 1 Introductio...
