Texture‐dependent motion signals in primate middle temporal area. (4th October 2013)

• Record Type: Journal Article
• Authors: Gharaei, Saba; Tailby, Chris; Solomon, Selina S.; Solomon, Samuel G.
• Is Part Of: Journal of physiology. Volume 591:Number 22(2013:Nov.)
• Page Start: 5671
• Page End: 5690
• Publication Date: 2013-10-04
• Subjects: Physiology -- Periodicals; 612.005
• DOI: 10.1113/jphysiol.2013.257568
• Languages: English
• ISSNs: 0022-3751

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Key points</title> <p> <list id="l1" list-type="simple"> <list-item> <label> </label> <p>The receptive fields of neurons in the middle temporal (MT) area of primate visual cortex are an important stage in motion analysis. Some neurons in MT (pattern cells) can signal motion independent of contour orientation, but others (component cells) cannot; there is no systematic account of how responses in area MT depend on the spatial structure of images.</p> </list-item> <list-item> <label> </label> <p>We measured the extracellular response of neurons in area MT of anaesthetised marmoset monkeys to synthetic textures and natural images.</p> </list-item> <list-item> <label> </label> <p>Direction tuning of pattern cells was broad and largely stable against variation in spatial texture. Direction tuning of component cells was narrower than that of pattern cells when spatial textures contained few orientations, but tuning was not stable against variation in spatial texture.</p> </list-item> <list-item> <label> </label> <p>Response variability in all neurons was lower for rich spatial texture.</p> </list-item> <list-item> <label> </label> <p>Pattern and component cells may provide parallel analyses for motion vision.</p> </list-item> </list> </p> <p> <bold>Abstract </bold> Neurons in the middle temporal (MT) area of primate cortex provide an important stage in the analysis of visual motion. For simple stimuli such as bars and plaids some neurons in area MT – pattern cells – seem to signal motion independent of contour orientation, but many neurons – component cells – do not. Why area MT supports both types of receptive field is unclear. To address this we made extracellular recordings from single units in area MT of anaesthetised marmoset monkeys and examined responses to two‐dimensional images with a large range of orientations and spatial frequencies. Component and pattern cell response remained distinct during presentation of these complex spatial textures. Direction tuning curves were sharpest in component cells when a texture contained a narrow range of orientations, but were similar across all neurons for textures containing all orientations. Response magnitude of pattern cells, but not component cells, increased with the spatial bandwidth of the texture. In addition, response variability in all neurons was reduced when the stimulus was rich in spatial texture. Fisher information analysis showed that component cells provide more informative responses than pattern cells when a texture contains a narrow range of orientations, but pattern cells had more informative responses for broadband textures. Component cells and pattern cells may therefore coexist because they provide complementary and parallel motion signals.</p> </abstract>