J Manipulative Physiol Ther. 2000 May; 23(4): 246-51.

Use of a mental rotation reaction-time paradigm to measure the effects of upper cervical adjustments on cortical processing: a pilot study.

Kelly DD, Murphy BA, Backhouse DP.

Research Department, New Zealand School of Chiropractic, Auckland, New Zealand.

OBJECTIVES: To investigate the potential usefulness of a mental rotation paradigm in providing an objective measure of spinal manipulative therapy. To determine if cortical processing, as indicated by response time to a mental rotation reaction-time task, is altered by an upper cervical toggle recoil adjustment. DESIGN: Prospective, double-blind, randomized, controlled trial. SETTING: Chiropractic college clinical training facility. PARTICIPANTS: Thirty-six chiropractic student volunteers with clinical evidence of upper cervical joint dysfunction. INTERVENTION: Participants in the experimental group received a high-velocity, low-amplitude upper cervical adjustment. A non-intervention group was used to control for improvement in the mental rotation task as a result of practice effects. Outcome measures: Reaction time was measured for randomly varying angular orientations of an object appearing either as normal or mirror-reversed on a computer screen. RESULTS: The average decrease in mental rotation reaction time for the experimental group was 98 ms, a 14.9% improvement, whereas the average decrease in mental rotation reaction time for the control group was 58 ms, an 8. 0 improvement. The difference scores after the intervention time were significantly greater for the experimental group compared with the control group, as indicated by a one-tailed, 2-sample, equal variance Student t test, (P < 05). CONCLUSION: The results of this study have demonstrated a significant improvement in a complex reaction-time task after an upper cervical adjustment. These results provide evidence that upper cervical adjustment may affect cortical processing.