RESUMO
The processing of spatial and temporal detail was investigated in patients with multiple sclerosis. Normal observers and 13 patients with optic neuritis secondary to multiple sclerosis performed a battery of visual tests that included contrast sensitivity, temporal integration, evoked potentials, and visual masking. The multiple sclerosis patients exhibited losses of pattern processing, and these deficits became more noticeable when the patterns were presented briefly. Moreover, these patients exhibited diverse response patterns for the different visual tests. For some, temporal integration functions appeared severely attenuated, while evoked potential latency was within normal limits. Others displayed poor performance in the visual masking test, yet contrast sensitivity functions were comparable to those of the control group. We suggest that a battery of tests that incorporates spatial as well as temporal stimuli is necessary for the detection of visual dysfunction in multiple sclerosis.
Assuntos
Potenciais Evocados Visuais , Esclerose Múltipla/fisiopatologia , Percepção Espacial/fisiologia , Percepção do Tempo/fisiologia , Adulto , Humanos , Pessoa de Meia-Idade , Mascaramento Perceptivo , Testes VisuaisRESUMO
Luminance of extended-duration adapting field was varied from zero to a level sufficient to reduce brightness of a 5 ms test stimulus to a level just above increment threshold. Increasing the luminance of surrounds or solid adapting fields resulted in increased reaction time. With the perceived-order method, reduction of latency with increasing surround luminance (temporal facilitation) was obtained with a visual comparison stimulus but not with an auditory comparison. It was concluded that perceived motion is a necessary condition for temporal facilitation. This study and earlier studies using moving test stimuli may be explained by a shift from sustained to transient units with increasing adapting luminance.
Assuntos
Movimento (Física) , Tempo de Reação/fisiologia , Percepção Visual/fisiologia , Adaptação Ocular , Adulto , Percepção Auditiva/fisiologia , Feminino , Humanos , Luz , Masculino , Métodos , Estimulação Luminosa , Limiar SensorialRESUMO
Two-dimensional Fourier analysis of checkerboards reveals that major components are at a 45 degree angle to the check edges. After adapting to chromatic checkerboards, subjects who viewed achromatic grating stimuli reported that complementary color aftereffects are aligned with spatial frequency components rather than with the edges in the pattern.
