INTERACTIVITY INFLUENCES THE MAGNITUDE OF VIRTUAL REALITY ANALGESIA.

Despite medication with opioids and other powerful pharmacologic pain medications, most patients rate their pain during severe burn wound care as severe to excruciating. Excessive pain is a widespread medical problem in a wide range of patient populations. Immersive virtual reality (VR) distraction may help reduce pain associated with medical procedures. Recent research manipulating immersiveness has shown that a high tech VR helmet reduces pain more effectively than a low tech VR helmet. The present study explores the effect of interactivity on the analgesic effectiveness of virtual reality. Using a double blind design, in the present study, twenty-one volunteers were randomly assigned to one of two groups, and received a thermal pain stimulus during either interactive VR, or during non-interactive VR. Subjects in both groups individually glided through the virtual world, but one group could look around and interact with the environment using the trackball, whereas participants in the other group had no trackball. Afterwards, each participant provided subjective 0-10 ratings of cognitive, sensory and affective components of pain, and the amount of fun during the pain stimulus. Compared to the non-interactive VR group, participants in the interactive VR group showed 75% more reduction in pain unpleasantness (p < .005) and 74% more reduction in worst pain (p < .005). Interactivity increased the analgesic effectiveness of immersive virtual reality.

Fructose supports energy metabolism of some, but not all, axons in adult mouse optic nerve.

We used transmission electron microscopy (TEM) and electrophysiological techniques to characterize the morphology and stimulus-evoked compound action potential (CAP), respectively, of the adult mouse optic nerve (MON). Electrophysiological recordings demonstrated an identical CAP profile for each MON. An initial peak, smallest in area and presumably composed of the fastest-conducting axons displayed the lowest threshold for activation as expected for large axons. The second peak, the largest, was presumably composed of axons of intermediate diameter and conduction velocity, and the third peak was composed of the slowest and presumably smallest axons. In 10 mM fructose, the first CAP peak area was reduced by 78%, but the second and third peaks were unaffected. Histological analysis revealed a cross-sectional area of 33,346 microm2, containing 24,068 axons per MON. All axons were myelinated and axon diameter ranged from 0.09 to 2.58 microm, although 80 +/- 6% of the axons were <0.75 microm in diameter and only 0.6 +/- 0.3% of the axons were >2 microm in diameter. After bathing in fructose for 2 h 94 +/- 2% of normal appearing axons were <0.75 microm in diameter and none were >1.5 microm-all of the larger axons being grossly abnormal in structure. We conclude that fructose is unable to support function of the larger axons contributing to the first CAP peak, thus enabling us to identify a distinct population of axons that contributes to that peak.