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Testing neuronal accounts of anisotropic motion perception with computational modelling.

Wong W, Chiang Price NS - PLoS ONE (2014)

Bottom Line: We show in psychophysical experiments that reference repulsion and the oblique effect do not depend on the duration of a moving stimulus, and that brief adaptation to a single direction simultaneously causes a reference repulsion in the orientation domain, and the inverse of the oblique effect in the direction domain.We attempted to link these results to underlying neuronal anisotropies by implementing a large family of neuronal decoding models with parametrically varied levels of anisotropy in neuronal direction-tuning preferences, tuning bandwidths and spiking rates.We argue that the oblique effect arises from the anisotropic distribution of preferred directions evident in V1 and MT, but that reference repulsion occurs separately, perhaps reflecting a process of categorisation occurring in higher-order cortical areas.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Monash University, Victoria, Australia.

ABSTRACT
There is an over-representation of neurons in early visual cortical areas that respond most strongly to cardinal (horizontal and vertical) orientations and directions of visual stimuli, and cardinal- and oblique-preferring neurons are reported to have different tuning curves. Collectively, these neuronal anisotropies can explain two commonly-reported phenomena of motion perception - the oblique effect and reference repulsion - but it remains unclear whether neuronal anisotropies can simultaneously account for both perceptual effects. We show in psychophysical experiments that reference repulsion and the oblique effect do not depend on the duration of a moving stimulus, and that brief adaptation to a single direction simultaneously causes a reference repulsion in the orientation domain, and the inverse of the oblique effect in the direction domain. We attempted to link these results to underlying neuronal anisotropies by implementing a large family of neuronal decoding models with parametrically varied levels of anisotropy in neuronal direction-tuning preferences, tuning bandwidths and spiking rates. Surprisingly, no model instantiation was able to satisfactorily explain our perceptual data. We argue that the oblique effect arises from the anisotropic distribution of preferred directions evident in V1 and MT, but that reference repulsion occurs separately, perhaps reflecting a process of categorisation occurring in higher-order cortical areas.

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Relative performance for oblique versus cardinal directions.As in Figure 8, results are shown separately for three experienced observers (A–C) and averaged across eleven participants (D–F; mean ± SD). The ratio of oblique to cardinal orientation accuracy (A, D) and precision (B, E) was used to measure the strength of the oblique effect. Values greater than 1 indicate that orientation performance was better for cardinal directions than obliques. Error bars show geometric standard deviation. (C, F) The difference between arcsine-transformed oblique and cardinal reversal fractions; values greater than 0 indicate that direction performance was better for cardinal directions than obliques.
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pone-0113061-g009: Relative performance for oblique versus cardinal directions.As in Figure 8, results are shown separately for three experienced observers (A–C) and averaged across eleven participants (D–F; mean ± SD). The ratio of oblique to cardinal orientation accuracy (A, D) and precision (B, E) was used to measure the strength of the oblique effect. Values greater than 1 indicate that orientation performance was better for cardinal directions than obliques. Error bars show geometric standard deviation. (C, F) The difference between arcsine-transformed oblique and cardinal reversal fractions; values greater than 0 indicate that direction performance was better for cardinal directions than obliques.

Mentions: The perceptual anisotropies evident in Experiment 1 did not depend on viewing duration. Figure 9 shows the relative accuracy, precision and reversal fraction as a function of stimulus duration, expressed as the ratio of oblique and cardinal performance. Overall, there was no significant dependence of the relative orientation accuracy and precision on stimulus duration. Mixed-design ANOVAs assessing the log-transformed orientation anisotropy, grouped by stimulus duration and participant, showed no significant differences in relative orientation accuracy (F4, 10 = 2.24, p = 0.082) and relative orientation precision (F4, 10 = 0.94, p = 0.451). Reversal anisotropy, based on the arcsine-transformed difference between reversal fractions of cardinal and oblique directions, did significantly change with time (ANOVA, F4, 10 = 5.20, p = 0.002). A post-hoc analysis with Scheffé's method [31] showed reversals from 20 ms stimuli had a significantly lower reversal fraction difference than 30 ms stimuli (95% CI = [−0.157, −0.011]) and 640 ms stimuli (95% CI = [−0.157, −0.011]), suggesting relatively more cardinal reversals at the shorter duration. There were significant monotonic trends in relative orientation accuracy and reversal fraction difference by duration, but not for precision (Spearman's rho rank correlation; orientation accuracy anisotropy with log transformation: ρ = 0.311, p = 0.021; orientation precision anisotropy with log transformation: ρ = −0.039, p = 0.778; reversal fraction difference with arcsine transformation: ρ = 0.302, p = 0.025).


Testing neuronal accounts of anisotropic motion perception with computational modelling.

Wong W, Chiang Price NS - PLoS ONE (2014)

Relative performance for oblique versus cardinal directions.As in Figure 8, results are shown separately for three experienced observers (A–C) and averaged across eleven participants (D–F; mean ± SD). The ratio of oblique to cardinal orientation accuracy (A, D) and precision (B, E) was used to measure the strength of the oblique effect. Values greater than 1 indicate that orientation performance was better for cardinal directions than obliques. Error bars show geometric standard deviation. (C, F) The difference between arcsine-transformed oblique and cardinal reversal fractions; values greater than 0 indicate that direction performance was better for cardinal directions than obliques.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4237403&req=5

pone-0113061-g009: Relative performance for oblique versus cardinal directions.As in Figure 8, results are shown separately for three experienced observers (A–C) and averaged across eleven participants (D–F; mean ± SD). The ratio of oblique to cardinal orientation accuracy (A, D) and precision (B, E) was used to measure the strength of the oblique effect. Values greater than 1 indicate that orientation performance was better for cardinal directions than obliques. Error bars show geometric standard deviation. (C, F) The difference between arcsine-transformed oblique and cardinal reversal fractions; values greater than 0 indicate that direction performance was better for cardinal directions than obliques.
Mentions: The perceptual anisotropies evident in Experiment 1 did not depend on viewing duration. Figure 9 shows the relative accuracy, precision and reversal fraction as a function of stimulus duration, expressed as the ratio of oblique and cardinal performance. Overall, there was no significant dependence of the relative orientation accuracy and precision on stimulus duration. Mixed-design ANOVAs assessing the log-transformed orientation anisotropy, grouped by stimulus duration and participant, showed no significant differences in relative orientation accuracy (F4, 10 = 2.24, p = 0.082) and relative orientation precision (F4, 10 = 0.94, p = 0.451). Reversal anisotropy, based on the arcsine-transformed difference between reversal fractions of cardinal and oblique directions, did significantly change with time (ANOVA, F4, 10 = 5.20, p = 0.002). A post-hoc analysis with Scheffé's method [31] showed reversals from 20 ms stimuli had a significantly lower reversal fraction difference than 30 ms stimuli (95% CI = [−0.157, −0.011]) and 640 ms stimuli (95% CI = [−0.157, −0.011]), suggesting relatively more cardinal reversals at the shorter duration. There were significant monotonic trends in relative orientation accuracy and reversal fraction difference by duration, but not for precision (Spearman's rho rank correlation; orientation accuracy anisotropy with log transformation: ρ = 0.311, p = 0.021; orientation precision anisotropy with log transformation: ρ = −0.039, p = 0.778; reversal fraction difference with arcsine transformation: ρ = 0.302, p = 0.025).

Bottom Line: We show in psychophysical experiments that reference repulsion and the oblique effect do not depend on the duration of a moving stimulus, and that brief adaptation to a single direction simultaneously causes a reference repulsion in the orientation domain, and the inverse of the oblique effect in the direction domain.We attempted to link these results to underlying neuronal anisotropies by implementing a large family of neuronal decoding models with parametrically varied levels of anisotropy in neuronal direction-tuning preferences, tuning bandwidths and spiking rates.We argue that the oblique effect arises from the anisotropic distribution of preferred directions evident in V1 and MT, but that reference repulsion occurs separately, perhaps reflecting a process of categorisation occurring in higher-order cortical areas.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Monash University, Victoria, Australia.

ABSTRACT
There is an over-representation of neurons in early visual cortical areas that respond most strongly to cardinal (horizontal and vertical) orientations and directions of visual stimuli, and cardinal- and oblique-preferring neurons are reported to have different tuning curves. Collectively, these neuronal anisotropies can explain two commonly-reported phenomena of motion perception - the oblique effect and reference repulsion - but it remains unclear whether neuronal anisotropies can simultaneously account for both perceptual effects. We show in psychophysical experiments that reference repulsion and the oblique effect do not depend on the duration of a moving stimulus, and that brief adaptation to a single direction simultaneously causes a reference repulsion in the orientation domain, and the inverse of the oblique effect in the direction domain. We attempted to link these results to underlying neuronal anisotropies by implementing a large family of neuronal decoding models with parametrically varied levels of anisotropy in neuronal direction-tuning preferences, tuning bandwidths and spiking rates. Surprisingly, no model instantiation was able to satisfactorily explain our perceptual data. We argue that the oblique effect arises from the anisotropic distribution of preferred directions evident in V1 and MT, but that reference repulsion occurs separately, perhaps reflecting a process of categorisation occurring in higher-order cortical areas.

Show MeSH
Related in: MedlinePlus