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Integration of Semi-Circular Canal and Otolith Cues for Direction Discrimination during Eccentric Rotations.

Soyka F, Bülthoff HH, Barnett-Cowan M - PLoS ONE (2015)

Bottom Line: Discrimination thresholds for eccentric rotations reduced with increasing radii, indicating that additional tangential accelerations (which increase with radius length) increased sensitivity.Our findings clearly show that information from the two organs is integrated.However the measured thresholds for 3 of the 5 eccentric rotations are even more sensitive than predictions from the optimal integration model suggesting additional non-vestibular sources of information may be involved.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Biological Cybernetics, Department: Human Perception, Cognition and Action, Tübingen, Germany.

ABSTRACT
Humans are capable of moving about the world in complex ways. Every time we move, our self-motion must be detected and interpreted by the central nervous system in order to make appropriate sequential movements and informed decisions. The vestibular labyrinth consists of two unique sensory organs the semi-circular canals and the otoliths that are specialized to detect rotation and translation of the head, respectively. While thresholds for pure rotational and translational self-motion are well understood surprisingly little research has investigated the relative role of each organ on thresholds for more complex motion. Eccentric (off-center) rotations during which the participant faces away from the center of rotation stimulate both organs and are thus well suited for investigating integration of rotational and translational sensory information. Ten participants completed a psychophysical direction discrimination task for pure head-centered rotations, translations and eccentric rotations with 5 different radii. Discrimination thresholds for eccentric rotations reduced with increasing radii, indicating that additional tangential accelerations (which increase with radius length) increased sensitivity. Two competing models were used to predict the eccentric thresholds based on the pure rotation and translation thresholds: one assuming that information from the two organs is integrated in an optimal fashion and another assuming that motion discrimination is solved solely by relying on the sensor which is most strongly stimulated. Our findings clearly show that information from the two organs is integrated. However the measured thresholds for 3 of the 5 eccentric rotations are even more sensitive than predictions from the optimal integration model suggesting additional non-vestibular sources of information may be involved.

No MeSH data available.


PSF Fit.A psychometric function (PSF) fit: the percentage of rightward responses is plotted against the stimulus intensity (positive intensities correspond to rightward motions). The sizes of the blue circles correspond to how often a certain stimulus was tested. The blue line shows the fit for the psychometric function based on maximum likelihood estimation.
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pone.0136925.g003: PSF Fit.A psychometric function (PSF) fit: the percentage of rightward responses is plotted against the stimulus intensity (positive intensities correspond to rightward motions). The sizes of the blue circles correspond to how often a certain stimulus was tested. The blue line shows the fit for the psychometric function based on maximum likelihood estimation.

Mentions: Data for a discrimination task can be analyzed by fitting a psychometric function ranging from 0% rightward answers to 100% rightward answers. This allows for an estimate of the point of subjective equality between leftward and rightward motions (the bias μ) as well as an estimate for the discrimination threshold σ (Fig 3). The psychometric function was modeled as a cumulative normal distribution with the two parameters μ and σ: . The best fitting parameters given the measurements were found by maximizing the log-likelihood of the model: , where the sum runs over all 150 trials, responsei equals 1 if the response was rightward and 0 otherwise, and stimulusi is the stimulus intensity of the i-th trial.


Integration of Semi-Circular Canal and Otolith Cues for Direction Discrimination during Eccentric Rotations.

Soyka F, Bülthoff HH, Barnett-Cowan M - PLoS ONE (2015)

PSF Fit.A psychometric function (PSF) fit: the percentage of rightward responses is plotted against the stimulus intensity (positive intensities correspond to rightward motions). The sizes of the blue circles correspond to how often a certain stimulus was tested. The blue line shows the fit for the psychometric function based on maximum likelihood estimation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555836&req=5

pone.0136925.g003: PSF Fit.A psychometric function (PSF) fit: the percentage of rightward responses is plotted against the stimulus intensity (positive intensities correspond to rightward motions). The sizes of the blue circles correspond to how often a certain stimulus was tested. The blue line shows the fit for the psychometric function based on maximum likelihood estimation.
Mentions: Data for a discrimination task can be analyzed by fitting a psychometric function ranging from 0% rightward answers to 100% rightward answers. This allows for an estimate of the point of subjective equality between leftward and rightward motions (the bias μ) as well as an estimate for the discrimination threshold σ (Fig 3). The psychometric function was modeled as a cumulative normal distribution with the two parameters μ and σ: . The best fitting parameters given the measurements were found by maximizing the log-likelihood of the model: , where the sum runs over all 150 trials, responsei equals 1 if the response was rightward and 0 otherwise, and stimulusi is the stimulus intensity of the i-th trial.

Bottom Line: Discrimination thresholds for eccentric rotations reduced with increasing radii, indicating that additional tangential accelerations (which increase with radius length) increased sensitivity.Our findings clearly show that information from the two organs is integrated.However the measured thresholds for 3 of the 5 eccentric rotations are even more sensitive than predictions from the optimal integration model suggesting additional non-vestibular sources of information may be involved.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Biological Cybernetics, Department: Human Perception, Cognition and Action, Tübingen, Germany.

ABSTRACT
Humans are capable of moving about the world in complex ways. Every time we move, our self-motion must be detected and interpreted by the central nervous system in order to make appropriate sequential movements and informed decisions. The vestibular labyrinth consists of two unique sensory organs the semi-circular canals and the otoliths that are specialized to detect rotation and translation of the head, respectively. While thresholds for pure rotational and translational self-motion are well understood surprisingly little research has investigated the relative role of each organ on thresholds for more complex motion. Eccentric (off-center) rotations during which the participant faces away from the center of rotation stimulate both organs and are thus well suited for investigating integration of rotational and translational sensory information. Ten participants completed a psychophysical direction discrimination task for pure head-centered rotations, translations and eccentric rotations with 5 different radii. Discrimination thresholds for eccentric rotations reduced with increasing radii, indicating that additional tangential accelerations (which increase with radius length) increased sensitivity. Two competing models were used to predict the eccentric thresholds based on the pure rotation and translation thresholds: one assuming that information from the two organs is integrated in an optimal fashion and another assuming that motion discrimination is solved solely by relying on the sensor which is most strongly stimulated. Our findings clearly show that information from the two organs is integrated. However the measured thresholds for 3 of the 5 eccentric rotations are even more sensitive than predictions from the optimal integration model suggesting additional non-vestibular sources of information may be involved.

No MeSH data available.