Plasticity of the juvenile and adult rodent primary auditory cortex

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Mammalian brains are highly plastic during early postnatal life, allowing the developing nervous system to adapt to the particular environment experienced after birth. The primary auditory cortex (A1), responsible for processing complex sounds such as communication signals, exhibits substantially more plasticity in juvenile animals than in adults. However, even adult brains (including A1) retain a significant plasticity potential, providing the neural basis for life-long learning. The present application addresses four fundamental objectives regarding plasticity of the developing and mature A1, using rats as a model organism. #1: Determine the precise role of sensory (sound) experience in guiding the maturation and stabilization of A1 synapses. #2: Characterize the postnatal development of different auditory perceptual skills (e.g., discrimination of loudness, pitch, or rhythmic patterns) and the influence of early sound experience on this developmental trajectory. #3: Assess synaptic mechanisms of auditory learning in the adult A1. #4: Determine the role of brain-generated estrogen (synthesized and released by A1 neurons) in A1 plasticity and auditory learning. These objectives are met by precise manipulations of the acoustic environment during development, behavioral techniques allowing animals to learn to distinguish various sounds, as well as electrophysiological and pharmacological techniques to assess levels of plasticity expressed by A1 neurons. This research program creates rich training opportunities for highly qualified personnel, allowing graduate and undergraduate students to acquire mastery of sophisticated scientific and professional skills, thus preparing them for advanced careers in academic or industrial/technological settings. Overall, the research outlined here will significantly advance our understanding of the development of auditory perceptual skills and auditory learning in adult animals, including brain mechanisms mediating these phenomena. Given the importance of auditory signals in animal (including humans) communication, this work can also provide insights into the evolution and development of sensory and brain systems mediating the sophisticated communicative abilities of many mammalian species.