Biomaterial Database

Stimulus duration, neural adaptation, and sweep visual evoked potential acuity estimates. 1998

W H Ridder, and D McCulloch, and A M Herbert

Southern California College of Optometry, Fullerton 92831, USA.

OBJECTIVE Results in several studies have suggested that the visual evoked potential (VEP) amplitude can vary with stimulus duration. The purpose of this study was to determine whether acuity estimates obtained by extrapolation of the sweep VEP are altered by this adaptation effect. METHODS Sweep VEP data were obtained from 16 healthy observers under binocular viewing conditions. Data were acquired with a commercially available VEP unit using standard electrode recording techniques. Three sweeps (high spatial frequencies, medium spatial frequencies, and low spatial frequencies) were run. The subjects' visual acuity at the monitor distance was 6/6 for the high spatial frequency sweep. For the medium and low spatial frequency sweeps, the subjects were dioptrically blurred to 6/15 (medium spatial frequencies) or 6/30 (low spatial frequencies) at the monitor distance. Each sweep consisted of six spatial frequencies (contrast 80%; temporal frequency (TF) = 7.5 Hz; screen luminance = 100 candela [cd]/m2). For each spatial frequency, the stimulus duration was 8 seconds, partitioned into 1-second bins. A minimum of eight sweeps were obtained per subject. An acuity estimate was obtained for each second's data by fitting a line to the high spatial frequencies (excluding noise) and extrapolating this line to the x-axis. With this technique, estimates could not be obtained for 29 of 384 possible acuities. RESULTS The sweep VEP acuities for the 16 subjects did not change significantly over the 8 seconds of data collection for the high, medium, or low spatial frequency sweep (repeated measures analysis of variance [ANOVA]: high, P = 0.25; medium, P = 0.50; low, P = 0.23). In any given subject, there was a 1- to 2-octave range in acuity estimates over the 8 seconds of stimulus presentation (high, 1.23+/-0.417 octaves; medium, 1.41+/-0.593 octaves; low, 1.52+/-0.475 octaves; mean +/- SD). CONCLUSIONS These results suggest that there is not a significant change in sweep VEP acuity estimates over an 8-second stimulus presentation. Thus, neural adaptation does not significantly affect the clinical use of the sweep VEP.

UI	MeSH Term	Description	Entries
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D005074	Evoked Potentials, Visual	The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways.	Visual Evoked Response,Evoked Potential, Visual,Evoked Response, Visual,Evoked Responses, Visual,Potential, Visual Evoked,Potentials, Visual Evoked,Response, Visual Evoked,Responses, Visual Evoked,Visual Evoked Potential,Visual Evoked Potentials,Visual Evoked Responses
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000222	Adaptation, Physiological	The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.	Adaptation, Physiologic,Adaptations, Physiologic,Adaptations, Physiological,Adaptive Plasticity,Phenotypic Plasticity,Physiological Adaptation,Physiologic Adaptation,Physiologic Adaptations,Physiological Adaptations,Plasticity, Adaptive,Plasticity, Phenotypic
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014792	Visual Acuity	Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.	Acuities, Visual,Acuity, Visual,Visual Acuities
D014793	Visual Cortex	Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.	Area V2,Area V3,Area V4,Area V5,Associative Visual Cortex,Brodmann Area 18,Brodmann Area 19,Brodmann's Area 18,Brodmann's Area 19,Cortical Area V2,Cortical Area V3,Cortical Area V4,Cortical Area V5,Secondary Visual Cortex,Visual Cortex Secondary,Visual Cortex V2,Visual Cortex V3,Visual Cortex V3, V4, V5,Visual Cortex V4,Visual Cortex V5,Visual Cortex, Associative,Visual Motion Area,Extrastriate Cortex,Area 18, Brodmann,Area 18, Brodmann's,Area 19, Brodmann,Area 19, Brodmann's,Area V2, Cortical,Area V3, Cortical,Area V4, Cortical,Area V5, Cortical,Area, Visual Motion,Associative Visual Cortices,Brodmanns Area 18,Brodmanns Area 19,Cortex Secondary, Visual,Cortex V2, Visual,Cortex V3, Visual,Cortex, Associative Visual,Cortex, Extrastriate,Cortex, Secondary Visual,Cortex, Visual,Cortical Area V3s,Extrastriate Cortices,Secondary Visual Cortices,V3, Cortical Area,V3, Visual Cortex,V4, Area,V4, Cortical Area,V5, Area,V5, Cortical Area,V5, Visual Cortex,Visual Cortex Secondaries,Visual Cortex, Secondary,Visual Motion Areas