EFFECTS OF PHYSIOLOGICAL-CHANGES OF SERUM GLUCOSE ON THE PATTERN-VEP OF HEALTHY-VOLUNTEERS

The correlation between amplitude and latencies of the pattern-reversa l VEP (1.7-3.6 50% contrast) and the serum glucose was studied in six healthy, male volunteers (21-26 yr.; mean: 23.2 +/- 1.6 yr.). Pattern- VEP and serum glucose were obtained at 2-h intervals during a 8-h expe rimental session. The effect of spatial frequency on VEP (increased la tencies and amplitude with increasing spatial frequency) was removed s tatistically by computing the residuals from the nonlinear regression function vs. the spatial frequency. The residuals were then processed as stimulus-independent variables. At glucose serum concentrations wit hin the physiological range of variability (55-103 mg/dl), the P100 la tency increased (p < 0.04) with increasing serum glucose, with a 6.9% estimated latency difference between lower and higher glucose concentr ations. This correlation depends mostly on the association of shorter and longer P100 latencies with glucose concentration Values in the low er and upper portions of the normal concentration range respectively, but accounts for about 4% of the overall variance and may be accidenta l (therefore a potential bias in otherwise controlled VEP studies) or suggest functional relationships between glucose availability and visi on.