Developmental trends of performance monitoring measures in 7- to 25-year-olds: Unraveling the complex nature of brain measures

This study explores how trial-to-trial latency variability contributes to the developmental trends observed in ERN amplitude found in the incorrect trials of a performance monitoring task, the visual flanker task. An Adaptive Woody filter was used to measure and correct for the trial-to-trial latency variability of the ERN in 240 participants aged 7-25 years. Using three measures of latency variability, the degree of trial-to-trial latency variability was shown to decrease as the age of the participants increased from 7 to 25 years. The success of the Adaptive Woody filter technique to remove the trial-to-trial latency variability was demonstrated in a straightforward manner by the significant changes in the measures of fit and intraindividual variability obtained before and after applying the filter. After the latency variability effects were removed and adjusted averaged ERPs were obtained, a more subtle but significant nonlinear developmental trend was still found in the amplitude of the ERN component.

Low luminance/eyes closed and monochromatic stimulations reduce variability of flash visual evoked potential latency

CONTEXT

Visual evoked potentials are useful in investigating the physiology and pathophysiology of the human visual system. Flash visual evoked potential (FVEP), though technically easier, has less clinical utility because it shows great variations in both latency and amplitude for normal subjects.

AIM

To study the effect of eye closure, low luminance, and monochromatic stimulation on the variability of FVEPs.

SUBJECTS AND METHODS

Subjects in self-reported good health in the age group of 18-30 years were divided into three groups. All participants underwent FVEP recording with eyes open and with white light at 0.6 J luminance (standard technique). Next recording was done in group 1 with closed eyes, group 2 with 1.2 and 20 J luminance, and group 3 with red and blue lights, while keeping all the other parameters constant. Two trials were given for each eye, for each technique. The same procedure was repeated at the same clock time on the following day.

STATISTICAL ANALYSIS

Variation in FVEP latencies between the individuals (interindividual variability) and the variations within the same individual for four trials (intraindividual variability) were assessed using coefficient of variance (COV). The technique with lower COV was considered the better method.

RESULTS

Recording done with closed eyes, 0.6 J luminance, and monochromatic light (blue > red) showed lower interindividual and intraindividual variability in P2 and N2 as compared to standard techniques.

CONCLUSIONS

Low luminance flash stimulations and monochromatic light will reduce FVEP latency variability and may be clinically useful modifications of FVEP recording technique.