Baccus lab

I completed my PhD in 2018 under Steve Baccus, at Stanford University. The lab’s work generally focuses on how the cellular and circuit mechanisms in the retina implement ecologically- relevant visual computations. Much of the work has examined dynamic processing, in which retinal responses depend on the characteristics of the recent inputs. This includes properties such as adaptation, sensitizaition, and processing of natural visual stimuli. Most projects in the lab combine electrophysiology and computational modeling, examining the specific retinal function, the computation it performs, and the way in which it supports behaviors relevant to an animal’s behavior and survival.

Thesis research

My thesis research focuses on a type of dynamic processing discovered in the lab called sensitization. Following strong stimulation, a subset of the output cells in the retina actually increase their sensitivity. This can be understood as allowing the retina to process information even when the energy of the inputs suddenly decreases. A simple ecological example would be a moving predator which suddenly stops; sensitization is one mechanism whereby the visual system might maintain information about the location of the predator.

My own work extends this idea of sensitization, looking at two aspects:

  1. What is the spatial scale in the retina over which sensitization acts?
  2. Does the retina exhibit sensitization to specific patterns of input, rather than just the overall “strength” (or contrast) of the input?

I’ve found another form of sensitization, which acts over much larger distances on the retina than previously understood. This phenomenon, which I call peripheral sensitization, shows that the statistics of visual inputs in the distal retina increases the sensitivity in a local circuit.

In addition, some of my data shows that there are conditions under which this peripheral sensitizaiton is pattern-specific. That is, the sensitization is greater if the distal and proximal visual inputs “look alike”, i.e., have similar spatial and/or temporal statistics.

Publications

  • Long-range sensitization in the vertebrate retina and human perception. Naecker, B.N., & Baccus, S.A. BioRxiv

    This is the main publication derived from my thesis work. I’ve discovered a new type of dynamic processing in the retina, peripheral sensitization. The work demonstrates that input in a peripheral region increases the sensitivity in a central region. I also show an exciting and unusual connection with high-level human perception.

  • Synchronous inhibitory pathways create both efficiency and diversity in the retina. Manu, M., McIntosh, L.T., Kaster, D.B, Naecker, B.N., & Baccus, S.A. BioRxiv

    The work in this paper examines how the two broad classes of inhibitory interneurons (horizontal and amacrine cells) contribute to the linear receptive field surround of retinal ganglion cells.

  • Pyret: A Python package for analysis of neurophysiology data. 2017. Naecker, B.N., Maheswaranathan, N., Ganguli, S., & Baccus, S.A. Journal of Open Source Software.

    This paper documents the pyret Python package, which provides simple, powerful, and efficient implementations of a number of extremely common analyses used throughout sensory neuroscience.

  • Knowing which eye saw what: Utrocular discrimination in the context of 3D motion. Naecker, B.N., Huk, A.C., & Cormack, L.K. (2010). Society for Neuroscience Annual Meeting 2010 Poster.

    This poster paper presented psychophysical studies I performed while a research assistant at UT Austin. It examines the phenomenon of utrocular discrimination, the long-known ability of humans to perceive the eye of origin of a visual stimulus presented to only one of the two eyes. The work characterized the dependence of the phenomenon on the spatial and temporal frequencies of the stimuli.

  • Measurements of sensory readout during perceptual learning by human subjects on coarse and fine direction discrimination tasks. Naecker, B.N. & Gold, J.I. (2009). Society for Neuroscience Annual Meeting 2009 Poster.

    In this poster, I examined how humans learn a basic perceptual task: discriminating the direction in which an object is moving. The psychophysics and modeling work suggest that perceptual learning is achieved by subjects performing a more useful readout of the sensory representation of the object, while that representation itself remains relatively static.