The ability to improve and refine sensory facilities with practice - a process known as perceptual learning - is critical for the acquisition of a variety of complex behaviors, including speech and language. The fundamental importance of perceptual learning in shaping our day-to-day actions and perceptions makes it of vital interest to determine how training-based improvements are implemented in the brain.  The Caras lab explores this issue by measuring and manipulating the activation of neural circuits in freely-moving, behaving animals, with a primary focus on plasticity in auditory and top-down modulatory networks. The laboratory employs a number of advanced approaches, including wireless recordings from multichannel electrode arrays, optogenetics, chemogenetics, pharmacology, quantitative animal behavior, and neuroanatomical tracing.