
doi: 10.1007/bf00657007
pmid: 7290912
Although latency-corrected averaging and selective averaging represent frequency used alternatives to the time-locked averaging, little is known about the changes of the signal-to-noise ratio (SNR) associated with their application. For this reason, visual evoked responses (VERs) to blank and checkerboard patterned flashes of light (5.6 cd/m2) were recorded in 15 subjects using a referential (Oz - A1 + 2) and a bipolar (Oz - Pz) derivation, and interstimulus intervals (ISI) of 1.4s and 2.4s; SNRs were calculated for all combinations. With time-locked averaging (referential derivation) the mean SNR of single VERs was 0.35 to blank stimuli and 0.68 to patterned stimuli. With latency-corrected averaging, the means SNR rose to 0.56 (0.74), and with selective averaging it increased to 0.81 (1.00). A combined procedure of selective and latency-corrected averaging yielded the highest mean SNR values of single VERs: 0.98 (1.21). Increasing ISIs from 1.4 - 2.4s did not change the results; the mean SNR values were always higher in bipolar than in referential derivations. The selective, latency-corrected averaging produced higher SNRs, and the group mean number of detectable single VERs (62% of the single VERs to blank stimuli, and 74% of the single VERs to patterned stimuli) and the latency variability of the single VERs: -0.33 +/- 14.5 ms (blank stimulation) and -0.48 +/- 13.96 ms (patterned stimulation).
Adult, Electricity, Methods, Reaction Time, Evoked Potentials, Visual, Humans, Electroencephalography, Middle Aged, Mathematics, Photic Stimulation
Adult, Electricity, Methods, Reaction Time, Evoked Potentials, Visual, Humans, Electroencephalography, Middle Aged, Mathematics, Photic Stimulation
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 8 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 10% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
