The VMpo nucleus is an important mating station for pain and temperature signals mediated partly by the tractus spino-thalamicus via the spinal lemnic and partly by the tractus trigemino-thalamicus lateralis via the trigeminal limnic.
VMpo in turn links the pain and temperature signals to the insular cortex.
There are many indications that it is the VMpo core that is responsible for the genuine raw pain sensation regardless of cortical interaction.
The nucleus also receives a small influx of signals from the cerebellar nuclei.
The VMpo nucleus is located at the rear of the ventral posteriora(VP) core complex, which also includes the VPL and VPM nuclei.
Craig, A. D., Bushnell, M. C., Zhang, E.-T. & Blomquist, A. (1994) A thalamic nucleus specific for pain and temperature sensation. Nature 372, 770 - 773.