Narrow Results

The ability of nonlinear dynamical systems to process incoming information is a key problem of many fundamental and applied sciences. Information processing by computation with attractors (steady states, limit cycles and strange attractors) has been a subject of many publications. In this paper, we discuss a new direction in information dynamics based on neurophysiological experiments that can be applied for the explanation and prediction of many phenomena in living biological systems and for the design of new paradigms in neural computation. This new concept is the Winnerless Competition (WLC) principle. The main point of this principle is the transformation of the incoming identity or spatial inputs into identity-temporal output based on the intrinsic switching dynamics of the neural system. In the presence of stimuli the sequence of the switching, whose geometrical image in the phase space is a heteroclinic contour, uniquely depends on the incoming information. The key problem in the realization of the WLC principle is the robustness against noise and, simultaneously, the sensitivity of the switching to the incoming input. In this paper we prove two theorems about the stability of the sequential switching and give several examples of WLC networks that illustrate the coexistence of sensitivity and robustness.

Many biological networks are constructed with both regular and random connections between neurons. Bio-inspired systems should prevent this mixed topology of biological networks while the artificial system is still realizable. In this work, a bio-inspired network which has many analog realizations, Cellular Neural Network (CNN) is investigated under existing random connections in addition to its regular connections: Small-World Cellular Neural Network (SWCNN). Antennal Lobe, an organ in the olfaction system of insects, is modeled with SWCNN by extending the network with the use of two types of processors on the same network. The model combined with a classifier, SVM and overall system is tested with a five-class odor classification problem. While all neurons are connected to each other with direct or indirect connections in CNNs, the idea of short-cuts does not provide an improvement in classification performance but the results show that the fault tolerance ability of SWCNN is better than the classical CNN.

The purpose of this study was to evaluate the integrative effects of visual stimuli with chemical senses (olfactory and gustatory) stimuli in humans. Noninvasive measurement tools such as magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) are used to describe the mechanism of olfactory information processing in the human brain, and the neurophysiological properties of olfactory-related neurons are described.

The first study analyzed the interaction between visual and olfactory stimuli. Two odors (lemon and iso-valeric acid) were selected as pleasant and unpleasant odors, respectively and pleasant and unpleasant images were also selected. These cross-modal stimulus combinations were presented to the subject at random, and responses were measured by fMRI using an event related task. These results revealed that active brain areas with pleasant/unpleasant stimuli and matched/mismatched stimuli were different for memory and cognition.

The second study analyzed the interaction between visual and gustatory stimuli. Total four conditions (hunger–not hunger, and intake–not intake of monosodium glutamate (MSG)) were tested. Visual stimuli were food-related and nonfood-related photos. A visual analog scale (VAS) was also used to evaluate before and at regular time intervals after intake of MSG, and responses were measured using fMRI. Brain activity related to feeding desire after intake of MSG occurred near the insula cortex, and orbito-frontal cortex, among other areas.

These results on the integrative effects of visual stimuli with olfactory and gustatory stimuli, cross-modal and complex effects on olfaction and gustation were suggested to be obtained as an emotional response such as "pleasantness/unpleasantness" and as cognitive and memory responses such as "matching/mismatching" or the responses such as "feeding desire" afterwards intake of foods.