Visual-Chromatic Spatial and Temporal Frequency Responses in Elderly People
نویسندگان
چکیده
منابع مشابه
Temporal and spatial MRI responses to subsecond visual activation.
The temporal and spatial characteristics of oxygenation-sensitive MRI responses to very brief visual stimuli (five Hz reversing black and white checkerboard pattern versus darkness) were investigated (nine subjects) by means of serial single-shot gradient-echo echo-planar imaging (2.0 T, TR=400 ms, mean TE=54 ms, flip angle 30 degrees). The use of a 0.2-s stimulus and a 90-s control phase resul...
متن کاملBOLD human responses to chromatic spatial features.
Animal physiological and human psychophysical studies suggest that an early step in visual processing involves the detection and identification of features such as lines and edges, by neural mechanisms with even- and odd-symmetric receptive fields. Functional imaging studies also demonstrate mechanisms with even- and odd-receptive fields in early visual areas, in response to luminance-modulated...
متن کاملSpecializations for chromatic and temporal signals in human visual cortex.
Neurological case studies and qualitative measurements suggest that regions within human extrastriate cortex are specialized for different perceptual functions, including color. However, there are few quantitative measurements of human extrastriate color specializations. We studied the chromatic and temporal responses in several different clusters of human visual field maps using functional mag...
متن کاملSpatial frequency and visual discomfort
Images created from noise filtered to have an approximately 1/f amplitude spectrum were altered by adding excess energy concentrated at various spatial frequencies. The effects of this manipulation on judgements of visual discomfort were studied. Visual noise with a 1/f amplitude spectrum (typical of natural images) was judged more comfortable than any image with a relative increase in contrast...
متن کاملOrientation and spatial-frequency discrimination for luminance and chromatic gratings.
We have examined the accuracy of orientation and spatial-frequency discrimination for sine-wave gratings that vary in either luminance or color. The equiluminant chromatic gratings were modulated along either a tritanopic confusion axis (so that they were detectable on the basis of activity in only the short-wavelength-sensitive cones) or an axis of constant short-wavelength-sensitive cone exci...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: The Journal of the Institute of Image Information and Television Engineers
سال: 2003
ISSN: 1881-6908,1342-6907
DOI: 10.3169/itej.57.12_1697