Cooper, Leon N.
Selectivity and Metaplasticity in a Unified Calcium-Dependent Model
Yeung, Luk Chong, Blais, Brian S., Cooper, Leon N., Shouval, Harel Z.
A unified, biophysically motivated Calcium-Dependent Learning model has been shown to account for various rate-based and spike time-dependent paradigms for inducing synaptic plasticity. Here, we investigate the properties of this model for a multi-synapse neuron that receives inputs with different spike-train statistics. In addition, we present a physiological form of metaplasticity, an activity-driven regulation mechanism, that is essential for the robustness ofthe model.
Interactive Parts Model: An Application to Recognition of On-line Cursive Script
Neskovic, Predrag, Davis, Philip C., Cooper, Leon N.
In this work, we introduce an Interactive Parts (IP) model as an alternative to Hidden Markov Models (HMMs). We tested both models on a database of online cursive script. We show that implementations of HMMs and the IP model, in which all letters are assumed to have the same average width, give comparable results. However, in contrast to HMMs, the IP model can handle duration modeling without an increase in computational complexity.
Interactive Parts Model: An Application to Recognition of On-line Cursive Script
Neskovic, Predrag, Davis, Philip C., Cooper, Leon N.
In this work, we introduce an Interactive Parts (IP) model as an alternative to Hidden Markov Models (HMMs). We tested both models on a database of online cursive script. We show that implementations ofHMMs and the IP model, in which all letters are assumed to have the same average width, give comparable results. However, in contrast to HMMs, the IP model can handle duration modeling without an increase in computational complexity. 1 Introduction Hidden Markov models [9] have been a dominant paradigm in speech and handwriting recognitionover the past several decades. The success of HMMs is primarily due to their ability to model the statistical and sequential nature of speech and handwriting data.
Receptive Field Formation in Natural Scene Environments: Comparison of Single Cell Learning Rules
Blais, Brian S., Intrator, Nathan, Shouval, Harel Z., Cooper, Leon N.
We study several statistically and biologically motivated learning rules using the same visual environment, one made up of natural scenes, and the same single cell neuronal architecture. This allows us to concentrate on the feature extraction and neuronal coding properties of these rules. Included in these rules are kurtosis and skewness maximization, the quadratic form of the BCM learning rule, and single cell ICA. Using a structure removal method, we demonstrate that receptive fields developed using these rules depend on a small portion of the distribution. We find that the quadratic form of the BCM rule behaves in a manner similar to a kurtosis maximization rule when the distribution contains kurtotic directions, although the BCM modification equations are computationally simpler.
PATTERN CLASS DEGENERACY IN AN UNRESTRICTED STORAGE DENSITY MEMORY
Scofield, Christopher L., Reilly, Douglas L., Elbaum, Charles, Cooper, Leon N.
ABSTRACT The study of distributed memory systems has produced a number of models which work well in limited domains. However, until recently, the application of such systems to realworld problemshas been difficult because of storage limitations, and their inherent architectural (and for serial simulation, computational) complexity. Recent development of memories with unrestricted storage capacity and economical feedforward architectures has opened the way to the application of such systems to complex pattern recognition problems. However, such problems are sometimes underspecified by the features which describe the environment, and thus a significant portion of the pattern environment is often non-separable. We will review current work on high density memory systems and their network implementations.