Classifying Stimuli

Alexei Koulakov, Cold Spring Harbor Laboratory

Nervous system often faces the problem of classifying stimuli and making decisions based on these classifications. Neurons involved in these tasks can be divided into sensory and motor, according to their correlation with sensory stimulus or motor response. In this study we define the third class of neurons, responsible for making perceptual decisions. Our mathematical formalism allows weighting neuronal units according to their contribution to decision-making, thus narrowing the field for more detailed studies of the underlying mechanisms. For the purposes of quantifying the contributions of neuronal units to decisions we develop two measures of decision-making. The first, called topological decision-making, describes potential contribution of units based solely on their positioning in the network. It involves the information about network connectivity and does not require the knowledge of neuronal responses. The second measure, called physiological decision-making, describes the actual contributions, employing neuronal responses. We describe applications of our studies to molecular and social networks.