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Journal article

Neural coding of image structure and contrast polarity of Cartesian, hyperbolic and polar gratings in the primary and secondary visual cortex of the tree shrew

  • Poirot, Jordan Visual Cognition Laboratory, Department of Medicine, University of Fribourg, Switzerland
  • Luna, Paolo De Visual Cognition Laboratory, Department of Medicine, University of Fribourg, Switzerland
  • Rainer, Gregor Visual Cognition Laboratory, Department of Medicine, University of Fribourg, Switzerland
    03.02.2016
Published in:
  • Journal of Neurophysiology. - 2016, vol. 115, no. 4, p. 2000-2013
English We comprehensively characterize spiking and visual evoked potential (VEP) activity in tree shrew V1 and V2 using Cartesian, hyperbolic and polar gratings. Neural selectivity to structure of Cartesian gratings was higher than other grating classes in both visual areas. From V1 to V2, structure selectivity of spiking activity increased, while corresponding VEP values tended to decrease, suggesting that single neuron coding of Cartesian grating attributes improved while the cortical columnar organization of these neurons became less precise from V1 to V2. We observed that neurons in V2 generally exhibited similar selectivity for polar and Cartesian gratings, suggesting that structure of polar-like stimuli might be encoded as early as in V2. This hypothesis is supported by the preference shift from V1 to V2 toward polar gratings of higher spatial frequency, consistent with the notion that V2 neurons encode visual scene borders and contours. Neural sensitivity to modulations of polarity of hyperbolic gratings was highest among all grating classes and closely related to the visual receptive field (RF) organization of ON- and OFF- dominated subregions. We show that spatial RF reconstructions depend strongly on grating class, suggesting that intracortical contributions to RF structure are strongest for Cartesian and polar gratings. Hyperbolic gratings tend to recruit least cortical elaboration such that the RF maps are similar to those generated by sparse noise, which most closely approximate feed-forward inputs. Our findings complement previous literature in primates, rodents and carnivores and highlight novel aspects of shape representation and coding occurring in mammalian early visual cortex.
Faculty
Faculté des sciences et de médecine
Department
Département de Médecine
Language
  • English
Classification
Biological sciences
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/304742
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