17 Result(s)
within
T. Geisel
Neurosciences
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Chapter and Conference Paper
Hidden Assembly Dynamics and Correlated Neuronal Responses
Oscillatory neuronal responses have been suspected to reveal assembly formation by synchronization. We analyse these data in terms of a hidden-state model, the parameters of which are estimated directly from e...
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Chapter and Conference Paper
Emergence of Transient Oscillations in an Ensemble of Neurons
An interesting property of oscillatory responses in various areas of cat and monkey visual cortex as well as monkey sensorimotor cortex is that the local oscillations and spatial correlations do not persist du...
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Chapter
Alternating Predictable and Unpredictable States in Data From Cat Visual Cortex
Visual inspection of data from cat visual cortex reveals, that the recently discovered 50-Hz-oscillations do not consist of a permanent oscillatory signal during the whole period of stimulation, but instead di...
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Chapter
Field Discontinuities and Islands in a Model of Cortical Map Formation
The existence of field discontinuities, i.e. discontinuities in cortical maps of the retina is well established by neurophysiological investigations in a variety of species [1–4]. In cat, additional geometric ano...
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Chapter and Conference Paper
Map Structure from Pinwheel Position
We propose a mathematical description for the spatial organization of orientation preference in the visual cortex. In this approach the spatial pattern of orientation preference is predicted from position and ...
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Chapter and Conference Paper
Unification of Complementary Feature Map Models
Selforganizing feature maps serve as models for the organization of primary sensory areas and have many applications in technical pattern recognition. In most models the evolution of receptive field centers w : X
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Chapter and Conference Paper
Emergence of Long Range Order in Maps of Orientation Preference
The formation of feature-maps in the develo** visual cortex has become a central system for the study of cooperative phenomena in large neural networks, both theoretically[l, 2] and experimentally [3, 4]. Wi...
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Article
Formation of field discontinuities and islands in visual cortical maps
The representations of visual hemifields in the extrastriate areas of various species exhibit field discontinuities and islands. We propose that these violations of retinotopy are a developmental consequence o...
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Article
Uncovering the synchronization dynamics from correlated neuronal activity quantifies assembly formation
Synchronous network excitation is believed to play an outstanding role in neuronal information processing. Due to the stochastic nature of the contributing neurons, however, those synchronized states are diffi...
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Chapter and Conference Paper
Precise restoration of cortical orientation maps explained by hebbian dynamics of geniculocortical connections
It is widely assumed that experience dependence and variability of the individual layout of cortical columns are the hallmarks of activity-dependent self-organization during development. Recent optical imaging...
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Article
Analyzing phase transitions in high-dimensional self-organizing maps
The self-organizing map (SOM), a widely used algorithm for the unsupervised learning of neural maps, can be formulated in a low-dimensional ‘feature map’ variant which requires prespecified parameters (‘featur...
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Chapter
Reorganization of Ocular Dominance Columns
Formation of ocular dominance columns in many models can be analyzed in terms of the spectra of eigenvalues of the linearized dynamics. Depending on the noise level and on boundary conditions, the correspondin...
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Chapter
Identifying Oscillatory and Stochastic Neuronal Behavior with High Temporal Precision in Macaque Monkey Visual Cortex
We characterize the network dynamics underlying multi-unit activities from area MT of macaque monkey in terms of a hidden markov model (HMM) and compare our results to those previously obtained from cat visual...
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Chapter
Activity-Dependent Self-Organization of Orientation Preference Predicts a Transient Overproduction of Pinwheels during Visual Development
The pinwheel-like arrangement of iso-orientation domains around orientation centers is a ubiquitous structural element of orientation preference maps in primary visual cortex. Here we investigate how activity-...
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Chapter and Conference Paper
A Cortical Interpretation of ASSOMs
Self-organizing maps have been successfully used to model map formation in the visual cortex of mammals. When applying natural images as stimuli, properties of the maps obtained for low-dimensional input manif...
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Chapter and Conference Paper
Analysing the Context Dependence of Receptive Fields in Visual Cortex
Stimuli outside the classical receptive field of orientation-selective cells in the visual cortex can strongly modulate the response properties of these cells. Normally, stimuli with orientation contrasts lead...
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Article
Action Potential Onset Dynamics and the Response Speed of Neuronal Populations
The result of computational operations performed at the single cell level are coded into sequences of action potentials (APs). In the cerebral cortex, due to its columnar organization, large number of neurons ...
