Cognition is a collective term for complex but sophisticated mental processes such as attention, learning, social interaction, language production, decision making and other executive functions. For normal brain function, these higher-order functions need to be aptly regulated and controlled, and the physiology and cellular substrates for cognitive functions are under intense investigation. The loss of cognitive control is intricately related to pathological states such as schizophrenia, depression, attention deficit hyperactive disorder and addiction.Synchronized neural activity can be observed when the brain performs several important functions, including cognitive processes. As an example, gamma activity (30-80 Hz) predicts the allocation of attention and theta activity (4-12 Hz) is tightly linked to memory processes. A large body of work indicates that the integrity of local and global neural synchrony is mediated by interneuron networks and actuated by the balance of different neuromodulators.However, much knowledge is still needed on the functional role interneurons play in cognitive processes, i.e. how the interneurons contribute to local and global network processes subserving cognition, and ultimately play a role in behavior. In addition, we need to understand how neuro-modulators, such as dopamine, regulate interneuron function.The proposed project aims to functionally determine the specific role the parvalbumin interneurons and the neuromodulator dopamine in aspects of cognition, and in behavior. In addition, we ask the question if cognition can be enhanced.We are employing a true multidisciplinary approach where brain activity is recorded in conjunctions with optogenetic manipulations of parvalbumin interneurons in animals performing cognitive tasks. In one set of experiments knock-down of dopamine receptors specifically in parvalbumin interneurons is employed to probe how this neuromodulator regulate network functions.