Skip to main content
Publications of the Week

Laminar Distribution and Arbor Density of Two Functional Classes of Thalamic Inputs to Primary Visual Cortex

By October 26, 2021No Comments

Read the Publication

This week we profile a recent publication in Cell Reports from the laboratory of Dr. Jun Zhuang (pictured) at the Allen Institute for Brain Science.

Can you provide a brief overview of your lab’s current research focus?

Our lab is interested in understanding the structural and functional organizations of mammalian visual systems, focusing on the anatomical mechanisms of cortical computation. We use the mouse visual system as our model system and study how the visual information from the periphery is processed and perceived by the animal from both computational and anatomical perspectives. We take advantage of the genetic and viral tools developed at the Allen Institute to label specific types of cells, record their activities in response to internal and external stimuli, build mathematical models for their roles in information processing, and interrogate their structure, connectivity, and molecular features. Our overarching goal is to generate comprehensive and detailed knowledge about the components, organizations, and computations of the mammalian early visual system.

What is the significance of the findings in this publication?

Different types of visual information, such as the position of an object or the direction of an object’s motion, take separate routes to the primary visual cortex. In mice, it is under debate that whether the position information and motion direction information arrive at the primary visual cortex at different depths, where different cortical computations take place. To definitively settle this debate is difficult because these visual inputs are carried by tangled and ramifying axons thinner than a thousandth of a millimeter. In this study, by combining physiological and anatomical techniques, we traced and reconstructed complete axon arbors and carefully matched them with their functional imaging data to assign what types of visual information they carry. Our results show that the axons’ sensitive to object position and axons sensitive to motion direction have a similar depth profile but, unexpectedly, with different densities. These results definitively settled the debate in the field and revealed functional organizations of the major inputs to the primary visual cortex unseen before.

What are the next steps for this research?

The specific thalamic inputs to the primary visual cortex are the first step of cortical computation of visual information. Once reached cortex, the visual information is further processed by tens (if not hundreds) of different types of cortical neurons. These interconnected neurons form complex networks that perform specific computations at designated anatomical locations. Because the in vivo functions and in vitro features were mostly studied separately in previous studies, the precise role of each cell type in cortical computation and how they are integrated into the cortical network is unclear. Using the in vivo to in vitro coregistration technique developed in our study, we plan to link the in vivo function, anatomical structure, and molecular features of each cell type which will provide valuable insights into the mechanisms of cortical computation.

If you’d like us to mention your funding sources, please list them.

We wish to thank the Allen Institute for Brain Science founder, Paul G. Allen, for his vision, encouragement, and support. This work is supported by NIH BRAIN Initiative award R01NS104949 from the National Institute of Neurological Disorders and Stroke and award RF1MH117820 from the National Institute of Mental Health.

Read the Publication