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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.


Related in: MedlinePlus

Discrimination Thresholds.The left panel shows the thresholds for the head-centered rotation and translation. Each participant’s data is shown (crosses and circles) together with the arithmetic means (squares). The middle panel shows the thresholds for the eccentric rotation conditions (varying radii) in the rotational parameterization. The right panel shows the same thresholds but in the translational parameterization together with the conversion formula. The effect of the radius on the thresholds can be seen.
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pone.0136925.g004: Discrimination Thresholds.The left panel shows the thresholds for the head-centered rotation and translation. Each participant’s data is shown (crosses and circles) together with the arithmetic means (squares). The middle panel shows the thresholds for the eccentric rotation conditions (varying radii) in the rotational parameterization. The right panel shows the same thresholds but in the translational parameterization together with the conversion formula. The effect of the radius on the thresholds can be seen.

Mentions: The maximum likelihood parameters for the biases and the discrimination thresholds estimated by fitting psychometric functions to each participant’s data for all 7 conditions, as well as the raw data showing every single response can be found in the supplementary material [34]. Table 1 shows the mean biases for all conditions and Fig 4 shows the discrimination thresholds. Note that all means used herein are arithmetic means since our data did not justify the use of geometric means, which are often used for vestibular dominated self-motion perception thresholds (see data distribution in Fig 4). Nevertheless we did the analysis using geometric means as well and the results did not substantially differ. The discrimination thresholds for the eccentric rotations are shown in both possible parameterizations. One can simply convert between the parameterizations using the formula given in Fig 4. We provide both parameterizations to illustrate their relation, but from here on we will use the rotational parameterization only. All statistical analyses were performed using IBM SPSS Statistics 21 with a significance level of p = 0.05.


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

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

Discrimination Thresholds.The left panel shows the thresholds for the head-centered rotation and translation. Each participant’s data is shown (crosses and circles) together with the arithmetic means (squares). The middle panel shows the thresholds for the eccentric rotation conditions (varying radii) in the rotational parameterization. The right panel shows the same thresholds but in the translational parameterization together with the conversion formula. The effect of the radius on the thresholds can be seen.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0136925.g004: Discrimination Thresholds.The left panel shows the thresholds for the head-centered rotation and translation. Each participant’s data is shown (crosses and circles) together with the arithmetic means (squares). The middle panel shows the thresholds for the eccentric rotation conditions (varying radii) in the rotational parameterization. The right panel shows the same thresholds but in the translational parameterization together with the conversion formula. The effect of the radius on the thresholds can be seen.
Mentions: The maximum likelihood parameters for the biases and the discrimination thresholds estimated by fitting psychometric functions to each participant’s data for all 7 conditions, as well as the raw data showing every single response can be found in the supplementary material [34]. Table 1 shows the mean biases for all conditions and Fig 4 shows the discrimination thresholds. Note that all means used herein are arithmetic means since our data did not justify the use of geometric means, which are often used for vestibular dominated self-motion perception thresholds (see data distribution in Fig 4). Nevertheless we did the analysis using geometric means as well and the results did not substantially differ. The discrimination thresholds for the eccentric rotations are shown in both possible parameterizations. One can simply convert between the parameterizations using the formula given in Fig 4. We provide both parameterizations to illustrate their relation, but from here on we will use the rotational parameterization only. All statistical analyses were performed using IBM SPSS Statistics 21 with a significance level of p = 0.05.

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.


Related in: MedlinePlus