Personality and augmenting/reducing in visual and auditory evoked potentials

Previous studies have indicated a relationship between evoked potential augmenting/reducing and extraversion or sensation seeking. However, the proposed mechanism of protective inhibition can account for this fact only if the relationship generalizes across different modalities and response definitions. The present study was designed to test this, using six intensities of visual and six intensities of auditory stimuli along with the EPI and SSS questionnaires.For the visual stimuli, the slope of the P90-N120 amplitude at the vertex correlated significantly with both the extraversion and the disinhibition scales in the way that augmenting/reducing theory predicts.However, over the primary visual area, no component showed the same personality relationship as the vertex wave, and one early component showed the opposite. This result suggests that personality differences in VEPs may reflect different ways of allocating processing resources between primary and association areas, rather than a generalized tendency to inhibit strong stimuli.In the auditory modality, personality differences were not apparent in the amplitude slopes, possibly due to the confluence from primary and association areas in AEPs in the vertex lead.There was a general tendency for latencies to correlate positively with extraversion and disinhibition, in congruence with Eysenck's theory on the biological basis of extraversion.     

Augmenting/reducing assessed by evoked potentials and the Vando scale

College students selected for extreme evoked potential (EP) augmenting and reducing completed the Vando Reducing-Augmenting Scale (RAS). No significant correlation was found between the EP measure and the Vando RAS, although the RAS was related to sensation-seeking. Researchers are advised that the EP and RAS measures are not comparable.     

Lateral dominance and visual evoked potentials in albinos

Lateral preferences for the use of eye, hand, and foot were assessed in 17 male and female albino subjects, aged 15 to 52 yr. Visual evoked potential (VEP) recordings suggested that optic fibres were abnormally decussated in these subjects, as others have shown. Fewer albino subjects showed the lateral preference for the use of hand/eye and foot/eye similar to that of normals. It is postulated that the abnormal decussation of optic fibres may underlie the reduced preference for the use of the same hand and eye, and foot and eye, in albinos.     

Spatial property of motion visual evoked potentials.

The cortical evoked response to drifting patterns (motion visual evoked potentials) was investigated. When the direction of motion of the stimulus pattern was reversed upward or downward at intervals, the cortical evoked response was triggered at the moment when the pattern changed direction. The polarity reversal of the main negative component occurred between upper and lower visual field stimulations as seen in pattern reversal visual evoked potentials. Our study indicates these potentials have a compound property reflecting the visual field.     

Psychometric intelligence and visual evoked potentials: a replication

Previously we have reported significant correlations between EEG visual evoked potential (EP) parameters and scores on the Raven's Advanced Progressive Matrices (RAPM) test. This study is an attempt to replicate those findings in a new sample of 27 S s. The results provide further evidence that EP amplitude is related to intelligence-test performance. There is also confirmation that stimulus luminance levels influence the magnitude of EP amplitude/intelligence correlations. In addition, the results indicate that age may be a confounding variable.     

A microcomputer-based system for evoked-potential augmenting/reducing measurements

Evoked-potential measurements can readily be implemented on a microcomputer. We present as an example a system for obtaining an evoked-potential augmenting/reducing measure using the Apple II microcomputer. Specialized features of the PASCAL program and peripheral equipment are described.     

Monocular and binocular visual evoked potentials before and after cataract surgery

Visual evoked cortical potentials (VEPs) were recorded from an individual with a mature cataract in one eye. Stimulation was both monocular and binocular and VEPs were obtained from three occipital scalp sites. Comparisons of recordings taken prior to cataract removal and after removal showed a dramatic increase in amplitude of potentials derived through stimulation of the affected eye. Slight differences in hemispheric amplitude prior to surgery suggest a greater degree of opacity in one portion of the affected lens.     

The relationship between impulsiveness subtraits,trait anxiety,and visual N100 augmenting/reducing: A topographic analysis

The relationship between impulsiveness subtraits assessed by the Barratt Impulsiveness Scale (BIS-10), the trait anxiety subscale of the State-Trait Personality Inventory (STPI), and the topographic distribution of visual N100 augmenting/reducing (AR) was examined. Topographic event-related potential (ERP) data were collected from an array of 14 electrodes covering the left side of the head while subjects counted the total number of light flashes presented at two different but equiprobable intensities. Principal components analysis of the ERP data yielded a factor accounting for 13.9% of the total variance around the grand mean waveform that corresponded to the N100 wave clearly visible in the raw waveforms. For each subject by scalp locus combination, an AR score was computed by subtracting the factor score associated with the bright flashes from the factor score associated with the dim flashes. The correlations between AR scores and scores on the BIS-10 cognitive impulsiveness subscale were significant (P < 0.01) at all scalp loci with the exception of the extreme frontal and occipital poles. Correlations with the BIS-10 motor impulsiveness subscale had a similar scalp distribution. Correlations with the BIS-10 non-planning impulsiveness subscale were significant over the frontal third of the scalp, including the frontal pole. Trait anxiety was not significantly related at the 0.01 level to AR scores. Theoretical implications of these findings are discussed.     

Visual adaptation to a spatial contrast enhances visual evoked potentials

The effects of adaptation to the visual contrast of a counterphase grating were studied with visual evoked potentials (VEPs). The spatial frequency of the grating was 4 cpd, and its temporal frequency was 4 or 12 Hz. Steady-state VEPs were analyzed through an FFT (fast Fourier transform) algorithm. In the first experiment, contrast thresholds rose strongly just after the end of adaptation and declined regularly over time. The VEPs recorded in the medio-occipital lead showed an initial decrease in amplitude after adaptation, followed by an enhancement well above the preadaptation level and then a return to that level. The paradoxical enhancement of the VEP was found at both high and low contrast in both the medio-occipital lead and the right temporal lead of a right-handed subject. The left temporal leads showed a VEP enhancement at high contrast and a decline at a low value.     

Behavior of visual evoked potentials (pattern reversal VECP) in smokers

Twenty six clinically healthy smokers were studied with transient pattern visual-evoked potentials. In comparison with a sample of "normal" subjects we found a difference of some parameters (P less than 0.05): the P2-latency and the interocular difference of latency on average were 6-7 ms respectively 2 ms larger. Thirteen subjects have had a prolonged P2-latency (P less than 0.05) and/or a difference in interocular latencies larger than 5 ms. These findings may suggest on subclinical disturbances of visual system and indicators of an special sensitivity of that person. The findings are possibly related to tobacco-alcohol amblyopia.     

Abnormalities of visual evoked potentials by checkerboards in children with specific reading disability

Visual evoked potentials by checkerboards of varying check sizes were recorded in the two hemispheres of 16 specific reading disabled and 8 normal children. In most of the disabled subjects a gross hemisphere asymmetry was assessed, while in the control group the usual evoked potential symmetry was observed. In some disabled subjects the evoked potentials had a larger amplitude in the right hemisphere, while in others the amplitude was larger in the left hemisphere. In a small subgroup the evoked potentials were symmetrical, but they had a smaller amplitude than in the control subjects. The results, giving evidence of a dysfunction in basic visual processing, are discussed in the context of current literature on clinical subgroups and the interhemispheric relationship in the dyslexic syndrome.     

Comparison between the lambda response of eye-fixation-related potentials and the P100 component of pattern-reversal visual evoked potentials

The purpose of this study was to compare the lambda response of eye-fixation-related potentials (EFRPs) with the P100 component of pattern-reversal visual-evoked potentials. EFRPs were obtained by averaging EEGs time-locked to the offset of the saccade. The dipole of the lambda response and that of the P100 component were estimated by the dipole-tracing method (Musha & Homma, 1990). The locations of their dipoles at the occipital sites were very close to each other when the difference waveform, which was calculated by subtracting the EFRP to the patternless stimulus from the EFRP to the patterned stimulus, was used for the lambda response. This finding implies that the lambda response and P100 have a common neural generator in the visual cortex. However, the peak latency of the lambda response was shorter than that of P100. The saccades in the EFRP trial were considered to be the cause of the difference.     

Early modulation of visual perception by emotional arousal: Evidence from steady-state visual evoked brain potentials

Allocation of processing resources to emotional picture stimuli was examined using steady-state visual evoked brain potentials (ssVEPs). Participants viewed a set of 60 colored affective pictures from the International Affective Picture System, presented in a flickering mode at 10 Hz in order to elicit ssVEPs. Phase and amplitude of the 10-Hz ssVEP were examined for six picture categories: threat and mutilation (unpleasant), families and erotica (pleasant), and household objects and persons (neutral). Self-reported affective arousal and hedonic valence of the picture stimuli were assessed by means of subjective ratings. Viewing affectively arousing (unpleasant and pleasant) pictures was associated with enhanced ssVEP amplitude at parieto-occipital recording sites, as compared with neutral stimuli. Phase information suggested increased coactivation of right occipitotemporal and frontotemporal sources during processing of affectively arousing stimuli. These findings are consistent with reentrant modulation of early visual processing by distributed networks including subcortical and neocortical structures according to a stimulus's motivational relevance.