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Conjunctions between Motion and Disparity Are Encoded with the Same Spatial Resolution As Disparity Alone

Lookup NU author(s): Dr Fredrik Allenmark

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Abstract

Neurons in cortical area MT respond well to transparent streaming motion in distinct depth planes, such as caused by observer self-motion, but do not contain subregions excited by opposite directions of motion. We therefore predicted that spatial resolution for transparent motion/disparity conjunctions would be limited by the size of MT receptive fields, just as spatial resolution for disparity is limited by the much smaller receptive fields found in primary visual cortex, V1. We measured this using a novel "joint motion/disparity grating," on which human observers detected motion/disparity conjunctions in transparent random-dot patterns containing dots streaming in opposite directions on two depth planes. Surprisingly, observers showed the same spatial resolution for these as for pure disparity gratings. We estimate the limiting receptive field diameter at 11 arcmin, similar to V1 and much smaller than MT. Higher internal noise for detecting joint motion/disparity produces a slightly lower high-frequency cutoff of 2.5 cycles per degree ( cpd) versus 3.3 cpd for disparity. This suggests that information on motion/disparity conjunctions is available in the population activity of V1 and that this information can be decoded for perception even when it is invisible to neurons in MT.


Publication metadata

Author(s): Allenmark F, Read JCA

Publication type: Article

Publication status: Published

Journal: Journal of Neuroscience

Year: 2012

Volume: 32

Issue: 41

Pages: 14331-14343

Print publication date: 10/10/2012

Date deposited: 24/07/2014

ISSN (print): 0270-6474

ISSN (electronic): 1529-2401

Publisher: Society for Neuroscience

URL: http://dx.doi.org/10.1523/JNEUROSCI.3495-11.2012

DOI: 10.1523/JNEUROSCI.3495-11.2012


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