Substrate for Cross-talk Inhibition Between Thalamic Barreloids

A double-labeling protocol was used to determine whether thalamocortical and reticular thalamic cells with overlapping receptive fields form open or closed loop connections in the vibrissal system of the rat. Results show that individual reticular cells exclusively project to the barreloid representing the principal whisker of their receptive field. Furthermore, solid retrograde labeling of relay cells reveals that a large number extend dendrites outside their home barreloid. This feature, together with previous demonstrations that reticular thalamic axons principally contact the dendrites of relay cells, provide a morphological substrate for cross-talk inhibition between thalamic barreloids.