Behavior, in this context, is thought, language, feeling, perception, learning, movement, sensing, planning, creativity, and other meanings that are

attached to the word behavior in everyday use. However, the actual nature of the psychobiological transform is extremely vague. The reason for this vagueness is the apparent complexity of the biological and behavioral realms, which include an Apoptosis Compound Library manufacturer immense number of states and of transitions between states that might be relevant. Operationally, behavioral and brain scientists find themselves in a situation where it is not at all clear what biological level of organization a psychological phenomenon should be transformed to, without losing the explanatory power of the transformation. Inhibitors,research,lifescience,medical Inhibitors,research,lifescience,medical For some researchers the state

of single synapses, potentiated or depressed, with all the molecular intricacies involved, is behaviorally relevant. There are neuroscientists for whom neuronal excitability, determined by the molecular states of membrane-embedded ionic channels, is behaviorally relevant. For others, the mere fact that a cortical neuron is a target for many thousands of other input neurons, none of which is capable on its own of firing the target neuron, suggests that the states of single synapses or single neurons cannot possibly be behaviorally relevant. For these scientists, the behaviorally relevant state concept may be Inhibitors,research,lifescience,medical realized in the form of a temporally structured firing pattern, or as an average firing rate in a population of neurons. Neural network theoreticians Inhibitors,research,lifescience,medical might reason in terms of abstract attractor states, while neurophysiologists might stress, for instance, the state of a rewarding system as defined in terms of electrical or neuro-pharmacological activity. Thus, the question of what biological level of organization a psychological phenomenon should be transformed to, without losing the explanatory power Inhibitors,research,lifescience,medical of that transformation, is open. The assumption underlying the studies reviewed here is that the most relevant

level of description is the level of neuronal populations and interactions between such populations. There is a significant body of data suggesting that even the simplest kind of mammalian behavior imaginable involves at least thousands of neurons, thousands of spikes, and hundreds of thousands of synapses. Indeed, much attention has been devoted to population level descriptions, resulting in theories such as neuronal assemblies, neuronal groups, all synfire chains, population codes, etc., in attempts to understand development and functionality of neural systems. As will be shown below, the study of the dynamical properties at the neuronal networks level gives hope that the gap between levels of description may be partially bridged. The central hypothesis of neuroscience is that behavior can and should be understood in terms of representational processes in the brain.