Chapter 7 FIG. 4. Changes in the size of a convergent, cutaneous receptive field of a spinal dorsal horn neu- ron following repetitive colorectal distention (CRD) (80 mm Hg, 20 sec) and after colonic instillation of 25% turpentine in peanut oil. There was no change in size of the receptive field during the first 2 hr of study (not shown), but the receptive field size increased during 2 hr of repeated CRD (every 4 min) and further increased 2 hr after irritation of the colon with turpentine. (From Ness and Gebhart, unpublished.) Click here to see the graphic at a different resolution