Figure 5.

Differing effects of intrathecal (i.t.) application of morphine on responses to innocuous brushing. A, Example of a pruriceptive VTT neuron's baseline response to brushing and greatly increased response in the presence of morphine. B, Mean histograms of response of pruriceptive cells (n = 10) to brushing under three conditions. C, Example of a nociceptive VTT neuron's baseline response to brushing and similar response in the presence of morphine. D, Mean histograms of response of nociceptive cells (n = 10) to brushing under three conditions. E, Normalized mean discharge rates during brushing for pruriceptive cells during four conditions. F, Effects of i.t. application of vehicle and morphine on normalized mean responses of nociceptive, pruriceptive, and low-threshold (n = 5) VTT neurons to brushing.