Organization of the cortico-thalamic connections

This video shows a composite of 80 injection sites of a viral tracer in the cortex (round spheres) and their major projections into the thalamus. We can clearly see that the spatial pattern of the injections is conserved in the thalamus. This kind of information was only previously available in piecemeal form, but with the comprehensive, standardized data in the Allen Mouse Brain Connectivity Atlas, we can reproducibly measure and visualize this topography.

Interestingly, projections pass through fiber tracts in the striatum, narrowing through the globus pallidus before fanning out throughout the thalamus, maintaining a high degree of spatial preservation from its cortical location.