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Contrast invariance of orientation tuning in the lateral geniculate nucleus of the feline visual system
Author(s) -
Viswanathan Sivaram,
Jayakumar Jaikishan,
Vidyasagar Trichur R.
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12991
Subject(s) - lateral geniculate nucleus , visual cortex , stimulus (psychology) , neuroscience , contrast (vision) , surround suppression , orientation column , psychology , visual perception , physics , striate cortex , optics , cognitive psychology , perception
Responses of most neurons in the primary visual cortex of mammals are markedly selective for stimulus orientation and their orientation tuning does not vary with changes in stimulus contrast. The basis of such contrast invariance of orientation tuning has been shown to be the higher variability in the response for low‐contrast stimuli. Neurons in the lateral geniculate nucleus ( LGN ), which provides the major visual input to the cortex, have also been shown to have higher variability in their response to low‐contrast stimuli. Parallel studies have also long established mild degrees of orientation selectivity in LGN and retinal cells. In our study, we show that contrast invariance of orientation tuning is already present in the LGN . In addition, we show that the variability of spike responses of LGN neurons increases at lower stimulus contrasts, especially for non‐preferred orientations. We suggest that such contrast‐ and orientation‐sensitive variability not only explains the contrast invariance observed in the LGN but can also underlie the contrast‐invariant orientation tuning seen at the level of the primary visual cortex.