Neuronal Basis of Contrast Discrimination

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Neuronal Basis of Contrast Discrimination (1999)

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by Geoffrey M. Boynton , Jonathan B. Demb , Gary H. Glover , David J. Heeger

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BibTeX

@MISC{Boynton99neuronalbasis,
    author = {Geoffrey M. Boynton and Jonathan B. Demb and Gary H. Glover and David J. Heeger},
    title = {Neuronal Basis of Contrast Discrimination},
    year = {1999}
}

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Abstract

Psychophysical contrast increment thresholds were compared with neuronal responses, inferred from functional magnetic resonance imaging (fMRI) to test the hypothesis that contrast discrimination judgements are limited by neuronal signals in early visual cortical areas. FMRI was used to measure human brain activity as a function of stimulus contrast, in each of several identifiable visual cortical areas. Contrast increment thresholds were measured for the same stimuli across a range of baseline contrasts using a temporal 2AFC paradigm. FMRI responses and psychophysical measurements were compared by assuming that: (1) fMRI responses are proportional to local average neuronal activity; (2) subjects choose the stimulus interval that evoked the greater average neuronal activity; and (3) variability in the observer's psychophysical judgements was due to additive (IID) noise. With these assumptions, FMRI responses in visual areas V1, V2d, V3d and V3A were found to be consistent with the psych...

Keyphrases

contrast discrimination neuronal basis fmri response visual area v1 psychophysical contrast increment threshold stimulus contrast average neuronal activity human brain activity local average neuronal activity neuronal signal baseline contrast psychophysical measurement stimulus interval contrast increment threshold neuronal response early visual cortical area functional magnetic resonance imaging contrast discrimination judgement psychophysical judgement several identifiable visual cortical area

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