UC San Diego

Every day we are immersed in a rich environment of signals to which our nervous system needs to sense and respond. At the sensory periphery, neurons instantaneously respond to stimuli like light and sound, laying the foundation for our perceptual experiences. As we ascend to higher-level brain areas, our cognitive landscape expands, embracing abstract concepts such as space. In this thesis, we unravel the hierarchical organization of neural responses in two specific brain regions, which provided insights into the underlying structure of their neural codes. Additionally, we explored the statistics of natural acoustics and delineated the hierarchies governing their organization.In Chapter 1, we studied spatial representation in hippocampus and demonstrated how neural circuits can achieve efficient representations with dynamic hierarchical organization. In Chapter 2, we studied auditory encoding in inferior colliculus and deciphered the coding scheme used there to support segmental processing of sounds. This involves a hierarchical organization of neural responses reflecting these neurons different response nonlinearities. In Chapter 3, we decomposed natural acoustics into fundamental building blocks and used hyperbolic geometry to capture the correlation statistics among them. The results informed us of the layered structures within various natural acoustics, which also implied a generative model of sounds.