Descending connections

The somatosensory cortex has a reciprocal connection with all of the subcortical structures that relay sensory input to it. The downward pathway is made by the corticospinal (pyramidal) tract either directly or through its connections with the brainstem reticular nuclei. Such back projections have a somatotopic mapping exactly in register with the ascending DCML pathway. They are possibly the vehicle by which the somatosensory input can be selectively filtered as an attention mechanism. For illustration, a lot of the time we are not aware of the sensations caused by the clothes.