Gender factor in longer P100 latency of elderly persons

The Relationship of Physical Activity History to Pattern-Reversal Evoked-Potential Components in Young and Older Men and Women

Latencies and peak-to-peak amplitudes of pattern-reversal evoked-potential (PREP) components of active and inactive community-dwelling healthy 61- to 77-year-olds were compared with those of active and inactive 18- to 31-year-olds to determine whether long-term physical activity involvement was associated with attenuation of age-related changes in sensory processes. Binocular PREPs were derived for each of 2 check sizes (22 × 15 ft and 41 × 30 ft of visual angle) to provide increasing challenge of spatial resolution. Analyses of the latencies revealed significant effects for age, gender, and check size such that latencies were longer for older than for young participants, men than for women, and small than for larger check sizes. Amplitudes were larger in older adults for the P100-N150 peak-to-peak difference, but physical activity history was not associated with reduction of the observed age-related increases in component latencies and amplitude. As such, physical activity does not appear to attenuate age-related decline in visual sensory processing.

Pattern reversal evoked potentials: gender differences and age-related changes in amplitude and latency

This report is intended to complement the current body of literature by describing pattern reversal evoked potential (PREP) component amplitudes and latencies in a larger sample than has been previously studied and providing comparisons of males and females across the lifespan. Binocular PREPs were measured from 406 normal subjects, 6-80 years of age. In general, latencies were found to decrease during maturation, stabilize across early adulthood, then begin to increase sometime after the late 20s. There were minimal gender differences in latencies during development but males tended to have longer latencies than females during adulthood. Across the lifespan, amplitudes were larger for females. Results of regression analyses using the entire data set were compared to results of separate regression analyses for developmental years (6-20) and adulthood (21-80). Separate analyses appear to provide more useful descriptions of PREP latency and amplitude changes across the lifespan. It is clear that predicted normal values can vary depending on age range and relative proportion of males and females comprising a reference sample. Appropriate clinical values should be based on age- and sex-matched normal subjects and should be specific with regard to technical and methodological variables.

Visual evoked magnetic fields to flash and pattern in 100 normal subjects

The practicality of recording visual evoked magnetic fields in 100 subjects 15-87 yr of age using a single channel d.c. SQUID second order gradiometer in an unshielded environment was investigated. The pattern reversal response showed a major positive component between 90 and 120 msec (P100M) while the response to flash produced a major positive component between 90 and 140 msec (P2M). Latency norms of the P100M were more variable than the corresponding P100 and P2 visual evoked potentials. The latency of the P100M may show a steep increase with age in most subjects after about 55 yr whereas only a small trend of latency with age was detected for the flash P2M.

Brain electrical activity mapping of monocular P100 reveals another type of uncrossed asymmetry

Reference-independent analysis of monocular full-field P100 reveals another type of uncrossed asymmetry, not hitherto appreciated, and perhaps dependent on skull-impedance characteristics.

Amplitudes of visually evoked potentials to patterned stimuli: age and sex comparisons

Electrophysiological age and sex differences in visual pattern responsivity were investigated. Pattern reversal evoked potentials (PREPs) and visual evoked potentials (VEPs) to patterned and unpatterned flashes were recorded from 20 normal subjects in each of 4 groups: young females and males aged 25-35 years and older females and males aged 55-70 years. PREP waves N70-P100 and P100-N150 from the older women were significantly larger than those from subjects in the other groups; mean amplitudes for the young females, young males and older males were not different. A similar effect, unusually large potentials for the older women, was obtained for VEPs, but only for VEPs elicited by patterned flashes and recorded from occipital scalp, i.e., an area overlying visual cortex which is sensitive to lines and edges. Our findings suggest that the visual system of older females is unusually responsive to patterned stimuli.