Monday, February 6, 2017, 12:00– 1:30 pm, in 489 Minor Hall
Optical Tools for Unraveling Whole-brain Neuronal Circuit Dynamics Underlying Behavior: From Retina to the Cortex
Alipasha Vaziri, PhD
The Rockefeller University, New York, NY
Optical technologies have been transformative for our current understanding of structure and function of neuronal circuits underlying behavior and are in many cases the limiting factors for pushing our understanding of the brain forward. I will discuss two different areas of research in our lab in this context.
In vision science despite of investigations for over seventy years, the absolute limits of human vision have remained unclear. Rod cells have been shown to respond to individual photons, yet whether this information is processed by the brain and is accessible on the behavioral level has remained a fundamental open question.
We have recently been able to show that humans can report a single photon incident on the eye with a probability significantly above chance . This was achieved by combining a two-alterative forced choice psychophysics procedure with quantum light source; a tool that allowed us to eliminate the irreducible variability of photon numbers in previous experiments. Furthermore, we found that the probability for reporting a single photon is modulated by the presence of an earlier photon. Our results and other applications of this tool may open up fundamentally new avenues for investigating yet undiscovered retinal pathways using quantum technologies.
Capturing the functional dynamics of large-scale neuronal circuits in awake behaving mammals at high speed and resolution has remained one of the main frontiers in systems neuroscience. I will discuss different high speed volumetric calcium imaging modalities developed in our lab that have allowed us to capture whole-brain neuronal dynamics at single cell resolution in small model systems [2-4] as well as the dynamics of several thousand neurons across cortical layers and in the hippocampus of awake behaving mice .
1. Tinsley, J. et al. Direct Detection of a Single Photon by Humans, Nature Communications, (2016) 7, 12172
2. Schrodel, T., et al., Brain-wide 3D imaging of neuronal activity in Caenorhabditis elegans with sculpted light. Nature Methods, (2013) 10(10): p. 1013
3. Prevedel, R., et al., Simultaneuos whole-animal 3D-imaging of neuronal activity using light-field microscopy. Nature Methods, (2014) 11, 727–730
4. Prevedel, R., et al., Fast volumetric calcium imaging across multiple cortical layers using sculpted light Nature Methods, (2016) 13, 1021-1028