4 YEAR PhD IN NEUROSCIENCE
Population coding in sensory systems
Our research is dedicated to understanding how information about the outside world is represented in the joint activity of populations of sensory neurons. For the last half century, physiologists have attempted to understand sensory systems by observing the activity of one neuron at a time. While this approach has yielded a basic understanding of sensory function, it has also revealed the importance of interactions between neurons. Recent technological developments have finally enabled the observation of the activity of many neurons in parallel, and our work takes advantage of these developments to study the role of neuronal interactions in sensory processing. The work in our lab is evenly split between auditory experiments (in vivo multi-electrode recordings) and computation (development of methods for the analysis and modeling of population spike trains). We also study the visual system together with our numerous collaborators.
- Adaptation of population interactions - Adaptation, the adjustment of neuronal processing strategies to changes in the statistical properties of sensory signals, is critical for sensory function in natural environments. Studies of adaptation in single neurons have revealed numerous important adaptive phenomena, but further study is required to determine whether additional forms of adaptation are emergent at the population level.
- Functional organization of the auditory midbrain - All of the information about the outside world that flows from our ears to our cortex is routed through the midbrain, the so-called ‘hub’ of the auditory system. Given recent demonstrations of the promise of the midbrain as a location for prosthetic implants in patients with neural deafness, it is critical that we gain a detailed understanding of its organization as soon as possible. New developments in multi-electrode recording technology enable large-scale electrical imaging and application of this technology to the auditory midbrain could provide a complete picture of its functional organization.
- Development of information theoretic tools for the study of population interactions - Information theory provides a quantitative framework for the study of the relationship between sensory stimuli and neuronal activity. While information theory has become invaluable in the study of single neurons, new methods must be developed for the analysis of the joint activity of multiple neurons.
N. A. Lesica and B. Grothe. Dynamic Spectrotemporal Feature Selectivity in the Auditory Midbrain. J. Neurosci. 28, 5412-5421 (2008).
N. A. Lesica, J. Jin, C. Weng, C. I. Yeh, D. A. Butts, G. B. Stanley, J. M. Alonso. Adaptation to stimulus contrast and correlations in the early visual pathway. Neuron. 55, 479-491 (2007).
N. A. Lesica, C. Weng, J. Jin, C. I. Yeh, J. M. Alonso, G. B. Stanley. Dynamic encoding of natural luminance sequences by LGN bursts. PLoS Biol 4(7): e209 (2006).