Organization and morphology of thalamocortical neurons of mouse ventral lateral thalamus

The ventral lateral nucleus of the thalamus (VL) serves as a central integrative center for motor control, receiving inputs from the cerebellum, striatum, and cortex and projecting to the primary motor cortex. We aimed to determine the somatotopy and morphological features of the thalamocortical neurons within mouse VL. Retrograde tracing studies revealed that whisker-related VL neurons were found relatively anterior and medial to those labeled following injection of retrograde tracer into hindpaw motor areas. Simultaneous injections of fluorescent microspheres in both cortical regions did not result in double-labeled neurons in VL. Quantitative analysis of dendritic and somatic morphologies did not reveal any differences between hindpaw and whisker thalamocortical neurons within VL. The morphology of the thalamocortical neurons within mouse VL is similar to those in other mammals and suggests that mouse can be used as a model system for studying thalamocortical transformations within the motor system as well as plasticity following sensory deprivation or enrichment.