Associative memory retrieval induced by fluctuations in a pulsed neural network

Chaotic pattern transitions in pulse neural networks

In models of associative memory composed of pulse neurons, chaotic pattern transitions where the pattern retrieved by the network changes chaotically were found. The network is composed of multiple modules of pulse neurons, and when the inter-module connection strength decreased, the stability of pattern retrieval changed from stable to chaotic. It was found that the mixed pattern of stored patterns plays an important role in chaotic pattern transitions.

Noise-enhanced categorization in a recurrently reconnected neural network

We investigate the interplay of recurrence and noise in neural networks trained to categorize spatial patterns of neural activity. We develop the following procedure to demonstrate how, in the presence of noise, the introduction of recurrence permits to significantly extend and homogenize the operating range of a feed-forward neural network. We first train a two-level perceptron in the absence of noise. Following training, we identify the input and output units of the feed-forward network, and thus convert it into a two-layer recurrent network. We show that the performance of the reconnected network has features reminiscent of nondynamic stochastic resonance: the addition of noise enables the network to correctly categorize stimuli of subthreshold strength, with optimal noise magnitude significantly exceeding the stimulus strength. We characterize the dynamics leading to this effect and contrast it to the behavior of a more simple associative memory network in which noise-mediated categorization fails.

Fluctuation-induced memory retrieval in a pulsed neural network storing sparse patterns with hierarchical correlations

An associative memory in a pulsed neural network composed of the FitzHugh-Nagumo models storing sparse patterns with hierarchical correlations is investigated. The memory patterns composed of 0/1 digits are represented by the synchronous periodic firings of the neurons. It is found that the target pattern and the OR pattern are retrieved individually by controlling the intensity of fluctuations in the system.