Research

Research goals and approach

Visual information from the retina targets multiple brain regions, including two image forming centers, the dorsal lateral geniculate of the thalamus and the superior colliculus. These set of connections form the primary and the secondary visual pathway respectively and have been investigated independently for decades. The flow of visual information meets at a later stage, in higher cortical areas. To this date, the respective role of each pathway remains unknown and a clear picture of the orchestrated process that is vision is still lacking. Major obstacles in understanding vision have been the lack of tools to conduct studies in awake animals, discrepancies in findings and approaches, and an oversimplified conceptual framework, in which visual information is processed linearly, from the periphery to the cortex.

 

One of the Savier lab research goal is to understand how and why visual information is distributed in distinct brain centers and how visual information is shaped by our behaviors. To this end, we will harness the power of a comparative approach in awake animals and directly compare the implementation of visual processes in mice and tree shrews. This comparative study will interrogate the role of each visual pathway by comparing the anatomy, the distribution of visual response and how behavior shapes these responses. The development of recent molecular and neuromodulation tools will allow the isolation and manipulation of the same-cell-type across species, thus answering fundamental questions about the emergence of visual response properties and more generally on the neuronal encoding of visual information.

 

Techniques in the lab

Tree shrew and mice:

 The Savier lab will use complementary animal models, the mouse and the tree shrew. Mice have become the gold standard for system neuroscience due to the numerous advantages they offer:  they’re easy to maintain, resilient, display social behavior and thousands of genetically modified strains are readily available. Tree shrews feature an extremely well-developed visual system, with features that are similar to primate, such as a layered lateral geniculate nucleus and orientation columns in the visual cortex. Moreover, their superior colliculus is laminated and greatly expended when compared to mice and primates. These unique characteristics make tree shrews a uniquely well-suited model to investigated the integration of visual integration across structures.

 

Imaging and electrophysiology:

The Savier lab uses electrophysiology and imaging, which have different yields and spatial and temporal resolution. Imaging allows the chronic investigation of neurons and assess how responses vary in different context. In addition, imaging allows the interrogation of the spatial distribution of different cells together with their morphological identification. However, this method lacks the temporal resolution to address subtle changes in cell response properties. Furthermore, investigating deeper layers remains extremely challenging. To overcome these challenges, electrophysiological approaches will be implemented in parallel and used to simultaneously investigate different brain regions in awake animals.