1 Hebb pointed at the tight connection between synchronization at the population level, representation, and learning. He suggested that the “… the simplest instance of a representative process (image or idea)” is a neuronal assembly, a group of “association-area cells” that share similar static and dynamic response properties when activated through specific receptors. Moreover, viewed from a perspective of purely mathematical principles derived from the machine learning and artificial intelligence realms, any agent that can learn complex Inhibitors,research,lifescience,medical tasks must develop some kind of internal representation of the outside world in which it resides. These and related conjectures from

the fields of psychology, engineering, and neurophysiology lead to the conclusion that the function of the nervous system, at the population or neuronal network level, can be studied in terms of three axes: representation, development, and learning. Representation denotes the study of how outside objects and sensations Inhibitors,research,lifescience,medical are “encoded” by neuronal Inhibitors,research,lifescience,medical activity and how these

activities interact to form higher-level complex functionality. Learning consists of the modification of these representations, their schemes, and the internal Selleck SB939 relations between them. The environment–development problem reduces to the following (rather vague) question: How does the richness of the environment experienced by a neural network during development affect its mature structure, topology, and functional capacities? In what follows we describe the use of multi-site interaction with large cortical networks developing ex vivo, in a culture dish, to study basic biophysical aspects of Inhibitors,research,lifescience,medical synchronization,

adaptation, learning, and representation Inhibitors,research,lifescience,medical in neuronal assemblies. We will briefly describe the experimental system, basic results regarding the self-organization of activity in this system, and the dynamical properties of neurons and networks in response to external stimulation. We show that the individual neurons and networks display very complex, history-dependent response patterns that pose constraints on possible representation schemes. Moreover, we will show the feasibility Thymidine kinase of such representation schemes and implications of their usage. Finally we will pose some future questions and research directions. THE EXPERIMENTAL SYSTEM: THE NEURONAL NETWORK OR ASSEMBLY Much of the research work aimed at the fundamental issues mentioned above, at the population level, has been carried out at the theoretical level. These theories are based on physiological data from small numbers of entities (neurons, synapses) and complemented by large-scale computer simulations. Most notable of these are physical theories of artificial neuronal networks.