The Experts below are selected from a list of 693 Experts worldwide ranked by ideXlab platform
Hillel J Chiel - One of the best experts on this subject based on the ideXlab platform.
-
The Journal of Experimental Biology 205, 3177–3206 (2002) Printed in Great Britain © The Company of Biologists Limited 2002
2008Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance image
-
Neural control exploits changing mechanical advantage and context dependence to generate different feeding responses in Aplysia
Biological Cybernetics, 2004Co-Authors: Gregory P. Sutton, David M Neustadter, Patrick E Crago, Elizabeth V Mangan, Randall D. Beer, Hillel J ChielAbstract:How does neural control reflect changes in mechanical advantage and muscle function? In the Aplysia feeding system a protractor muscle’s mechanical advantage decreases as it moves the structure that grasps food (the radula/Odontophore) in an anterior direction. In contrast, as the radula/Odontophore is moved forward, the jaw musculature’s mechanical advantage shifts so that it may act to assist forward movement of the radula/Odontophore instead of pushing it posteriorly. To test whether the jaw musculature’s context-dependent function can compensate for the falling mechanical advantage of the protractor muscle, we created a kinetic model of Aplysia ’s feeding apparatus. During biting, the model predicts that the reduction of the force in the protractor muscle I2 will prevent it from overcoming passive forces that resist the large anterior radula/Odontophore displacements observed during biting. To produce protractions of the magnitude observed during biting behaviors, the nervous system could increase I2’s contractile strength by neuromodulating I2, or it could recruit the I1/I3 jaw muscle complex. Driving the kinetic model with in vivo EMG and ENG predicts that, during biting, early activation of the context-dependent jaw muscle I1/I3 may assist in moving the radula/Odontophore anteriorly during the final phase of protraction. In contrast, during swallowing, later activation of I1/I3 causes it to act purely as a retractor. Shifting the timing of onset of I1/I3 activation allows the nervous system to use a mechanical equilibrium point that allows I1/I3 to act as a protractor rather than an equilibrium point that allows I1/I3 to act as a retractor. This use of equilibrium points may be similar to that proposed for vertebrate control of movement.
-
a kinematic model of swallowing in aplysia californica based on radula Odontophore kinematics and in vivo magnetic resonance images
The Journal of Experimental Biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance images.
The Journal of experimental biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
Radula-centric and Odontophore-centric kinematic models of swallowing in Aplysia californica.
The Journal of experimental biology, 2002Co-Authors: Richard F Drushel, David M Neustadter, Patrick E Crago, Benjamin W Adams, Greg P Sutton, Elizabeth V Mangan, Hillel J ChielAbstract:Two kinematic models of the radula/Odontophore of the marine mollusc Aplysia californica were created to characterize the movement of structures inside the buccal mass during the feeding cycle in vivo. Both models produce a continuous range of three-dimensional shape changes in the radula/Odontophore, but they are fundamentally different in construction. The radulacentric model treats the radular halves as rigid bodies that can pitch, yaw and roll relative to a fixed radular stalk, thus creating a three-dimensional shape. The Odontophore-centric model creates a globally convex solid representation of the radula/Odontophore directly, which then constrains the positions and shapes of internal structures. Both radula/Odontophore models are placed into a pre-existing kinematic model of the I1/I3 and I2 muscles to generate three-dimensional representations of the entire buccal mass. High-temporal-resolution, mid-sagittal magnetic resonance (MR) images of swallowing adults in vivo are used to provide non-invasive, artifact-free shape and position parameter inputs for the models. These images allow structures inside the buccal mass to be visualized directly, including the radula, radular stalk and lumen of the I1/I3 cavity. Both radula-centric and Odontophore-centric models were able to reproduce two-dimensional, mid-sagittal radula/Odontophore and buccal mass kinematics, but the Odontophore-centric model's predictions of I1/I3, I2 and I7 muscle dimensions more accurately matched data from MR-imaged adults and transilluminated juveniles.
David M Neustadter - One of the best experts on this subject based on the ideXlab platform.
-
The Journal of Experimental Biology 205, 3177–3206 (2002) Printed in Great Britain © The Company of Biologists Limited 2002
2008Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance image
-
Neural control exploits changing mechanical advantage and context dependence to generate different feeding responses in Aplysia
Biological Cybernetics, 2004Co-Authors: Gregory P. Sutton, David M Neustadter, Patrick E Crago, Elizabeth V Mangan, Randall D. Beer, Hillel J ChielAbstract:How does neural control reflect changes in mechanical advantage and muscle function? In the Aplysia feeding system a protractor muscle’s mechanical advantage decreases as it moves the structure that grasps food (the radula/Odontophore) in an anterior direction. In contrast, as the radula/Odontophore is moved forward, the jaw musculature’s mechanical advantage shifts so that it may act to assist forward movement of the radula/Odontophore instead of pushing it posteriorly. To test whether the jaw musculature’s context-dependent function can compensate for the falling mechanical advantage of the protractor muscle, we created a kinetic model of Aplysia ’s feeding apparatus. During biting, the model predicts that the reduction of the force in the protractor muscle I2 will prevent it from overcoming passive forces that resist the large anterior radula/Odontophore displacements observed during biting. To produce protractions of the magnitude observed during biting behaviors, the nervous system could increase I2’s contractile strength by neuromodulating I2, or it could recruit the I1/I3 jaw muscle complex. Driving the kinetic model with in vivo EMG and ENG predicts that, during biting, early activation of the context-dependent jaw muscle I1/I3 may assist in moving the radula/Odontophore anteriorly during the final phase of protraction. In contrast, during swallowing, later activation of I1/I3 causes it to act purely as a retractor. Shifting the timing of onset of I1/I3 activation allows the nervous system to use a mechanical equilibrium point that allows I1/I3 to act as a protractor rather than an equilibrium point that allows I1/I3 to act as a retractor. This use of equilibrium points may be similar to that proposed for vertebrate control of movement.
-
a kinematic model of swallowing in aplysia californica based on radula Odontophore kinematics and in vivo magnetic resonance images
The Journal of Experimental Biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance images.
The Journal of experimental biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
Radula-centric and Odontophore-centric kinematic models of swallowing in Aplysia californica.
The Journal of experimental biology, 2002Co-Authors: Richard F Drushel, David M Neustadter, Patrick E Crago, Benjamin W Adams, Greg P Sutton, Elizabeth V Mangan, Hillel J ChielAbstract:Two kinematic models of the radula/Odontophore of the marine mollusc Aplysia californica were created to characterize the movement of structures inside the buccal mass during the feeding cycle in vivo. Both models produce a continuous range of three-dimensional shape changes in the radula/Odontophore, but they are fundamentally different in construction. The radulacentric model treats the radular halves as rigid bodies that can pitch, yaw and roll relative to a fixed radular stalk, thus creating a three-dimensional shape. The Odontophore-centric model creates a globally convex solid representation of the radula/Odontophore directly, which then constrains the positions and shapes of internal structures. Both radula/Odontophore models are placed into a pre-existing kinematic model of the I1/I3 and I2 muscles to generate three-dimensional representations of the entire buccal mass. High-temporal-resolution, mid-sagittal magnetic resonance (MR) images of swallowing adults in vivo are used to provide non-invasive, artifact-free shape and position parameter inputs for the models. These images allow structures inside the buccal mass to be visualized directly, including the radula, radular stalk and lumen of the I1/I3 cavity. Both radula-centric and Odontophore-centric models were able to reproduce two-dimensional, mid-sagittal radula/Odontophore and buccal mass kinematics, but the Odontophore-centric model's predictions of I1/I3, I2 and I7 muscle dimensions more accurately matched data from MR-imaged adults and transilluminated juveniles.
Richard F Drushel - One of the best experts on this subject based on the ideXlab platform.
-
The Journal of Experimental Biology 205, 3177–3206 (2002) Printed in Great Britain © The Company of Biologists Limited 2002
2008Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance image
-
a kinematic model of swallowing in aplysia californica based on radula Odontophore kinematics and in vivo magnetic resonance images
The Journal of Experimental Biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance images.
The Journal of experimental biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
Radula-centric and Odontophore-centric kinematic models of swallowing in Aplysia californica.
The Journal of experimental biology, 2002Co-Authors: Richard F Drushel, David M Neustadter, Patrick E Crago, Benjamin W Adams, Greg P Sutton, Elizabeth V Mangan, Hillel J ChielAbstract:Two kinematic models of the radula/Odontophore of the marine mollusc Aplysia californica were created to characterize the movement of structures inside the buccal mass during the feeding cycle in vivo. Both models produce a continuous range of three-dimensional shape changes in the radula/Odontophore, but they are fundamentally different in construction. The radulacentric model treats the radular halves as rigid bodies that can pitch, yaw and roll relative to a fixed radular stalk, thus creating a three-dimensional shape. The Odontophore-centric model creates a globally convex solid representation of the radula/Odontophore directly, which then constrains the positions and shapes of internal structures. Both radula/Odontophore models are placed into a pre-existing kinematic model of the I1/I3 and I2 muscles to generate three-dimensional representations of the entire buccal mass. High-temporal-resolution, mid-sagittal magnetic resonance (MR) images of swallowing adults in vivo are used to provide non-invasive, artifact-free shape and position parameter inputs for the models. These images allow structures inside the buccal mass to be visualized directly, including the radula, radular stalk and lumen of the I1/I3 cavity. Both radula-centric and Odontophore-centric models were able to reproduce two-dimensional, mid-sagittal radula/Odontophore and buccal mass kinematics, but the Odontophore-centric model's predictions of I1/I3, I2 and I7 muscle dimensions more accurately matched data from MR-imaged adults and transilluminated juveniles.
-
Kinematics of the buccal mass during swallowing based on magnetic resonance imaging in intact, behaving Aplysia californica.
The Journal of experimental biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Hillel J ChielAbstract:A novel magnetic resonance imaging interface has been developed that makes it possible to image movements in intact, freely moving subjects. We have used this interface to image the internal structures of the feeding apparatus (i.e. the buccal mass) of the marine mollusc Aplysia californica. The temporal and spatial resolution of the resulting images is sufficient to describe the kinematics of specific muscles of the buccal mass and the internal movements of the main structures responsible for grasping food, the radula and the Odontophore. These observations suggest that a previously undescribed feature on the anterior margin of the Odontophore, a fluid-filled structure that we term the prow, may aid in opening the jaw lumen early in protraction. Radular closing during swallowing occurs near the peak of protraction as the radular stalk is pushed rapidly out of the Odontophore. Retraction of the Odontophore is enhanced by the closure of the lumen of the jaws on the elongated Odontophore, causing the Odontophore to rotate rapidly towards the esophagus. Radular opening occurs after the peak of retraction and without the active contraction of the protractor muscle 12 and is due, in part, to the movement of the radular stalk into the Odontophore. The large variability between responses also suggests that the great flexibility of swallowing responses may be due to variability in neural control and in the biomechanics of the ingested food and to the inherent flexibility of the buccal mass.
Wasim Ahmad - One of the best experts on this subject based on the ideXlab platform.
-
Two new species of the genus Coomansinema Ahmad and Jairajpuri, 1989 (Nematoda: Dorylaimida) with a key to its species
Helminthologia, 2019Co-Authors: Wasim Ahmad, P. Mushtaq, Shahnaz, S. KumarAbstract:Two new species of the genus Coomansinema Ahmad and Jairajpuri, 1989 are described and illustrated. C. japonicum n. sp. is characterized by having medium size body (L= 1.40 - 1.45 mm); lip region truncate with completely amalgamated lips; amphideal fovea goblet - shaped; 16 - 20 μm long odontostyle; 23 - 25 μm long Odontophore; comparatively anterior position of the second pair of pharyngeal glands; amphidelphic female genital system; longitudinal vulva; males with 48 - 54 μm long spicules; 7 - 8 spaced ventromedian supplements and tail long filiform in female and short conoid in male. C. longicaudatum n. sp. is characterized by having medium size body (L= 1.1 - 1.3 mm); lip region truncate, continuous with completely amalgamated lips; amphideal fovea cup - shaped; 16 - 17 μm long odontostyle; 19 - 20 μm long Odontophore; comparatively anterior position of the second pair of pharyngeal glands; amphidelphic female genital system; transverse vulva, intestinal - prerectum junction with a tongue - like structure and 210 - 269 μm long filiform tail. A key to its seven valid species is provided.
-
A new species of the rare nematode genus Rostrulium Siddiqi, 1995 (Nematoda: Dorylaimida: Tylencholaimidae) from India.
Zootaxa, 2019Co-Authors: Niraul Islam, Zarrin Imran, Wasim AhmadAbstract:Rostrulium indicum sp. n. is described and illustrated from Western Ghats, India. The new species is characterized by having a 2.1 mm long body; lip region offset by slight constriction; odontostyle 17.5 µm and Odontophore 18 µm long, guiding ring single; pharynx with slender anterior part which expands gradually into the cylindrical basal bulb occupying about 30% of total neck length; female genital system didelphic-amphidelphic, transverse vulva, short rounded conoid tail and male with 40 µm long spicules, lateral guiding pieces and three spaced ventromedian supplements. This is the first report of this rare genus since its original description from Cameroon.
-
Taxonomy of the genus Doryllium Cobb, 1920 (Nematoda: Dorylaimida) with description of two new and a known species.
Zootaxa, 2018Co-Authors: Wasim Ahmad, Sumaya Ahad, Niraul Islam, Dieter SturhanAbstract:Two new and a known species of the genus Doryllium Cobb, 1920 are described and illustrated. Doryllium enigmatum n. sp. is characterized by a body length of 0.40–0.52 mm; continuous lip region; rounded lips; asymmetrical odontostyle, 5–6 µm long, and flanged Odontophore 9–11 µm in length; pharynx with slender anterior part which expands into a slightly constricted pyriform basal bulb, occupying about 16–18% of total neck length; mono-opisthodelphic female genital system; 7–9 μm long anterior uterine sac; transverse vulva and rounded-hemispheroid tail. Doryllium asymmetricum n. sp. is characterized by its 0.52–0.63 mm long body; cap-like, slightly offset lip region; asymmetrical odontostyle, 6 µm in length and 9–11 µm long Odontophore with weak flanges; pharynx with slender anterior part which expands gradually into pear-shaped basal bulb, occupying about 16.4–18.5% of total neck length; mono-opisthodelphic female genital system; anterior uterine sac 17–30 μm in length, filled with sperms; transverse vulva and rounded-hemispheroid tail. D. minor is redescribed based on specimens collected from several localities in India and Germany. The diagnosis of the genus Doryllium is emended and a valid list of species with their synonymies and a diagnostic compendium of all the known species is provided.
-
Description of two new and two known species of the Genus Tylencholaimellus Cobb in M. V. Cobb, 1915 (Nematoda: Dorylaimida: Tylencholaimoidea).
Zootaxa, 2018Co-Authors: Wasim Ahmad, Sumaya AhadAbstract:Two new and two known species of the dorylaimid nematode genus Tylencholaimellus Cobb in M.V. Cobb, 1915 are described and illustrated. Tylencholaimellus arabicus sp. n. collected from Saudi Arabia is characterized by having small sized body (L= 0.66–0.83 mm); outer cuticle with distinct transverse striations; inner layer thick with fine transverse striations; lip region offset by a deep constriction, inner liplets slightly raised; odontostyle 15–17 µm, Odontophore 8–10 µm, combined length 25–26 μm; female genital system mono-opisthodelphic; anterior uterine sac 0.5–1.3 times midbody diameter in length; transverse vulva and short conoid tail Tylencholaimellus masakii sp. n. collected from Japan is characterized by having small sized body (L= 0.77–0.81 mm); lip region offset by a slight constriction; labial disc present; odontostyle 11–12 µm, Odontophore 6–7 µm, combined length 18–18.5 μm; female genital system mono-opisthodelphic; anterior uterine sac 1.1–1.8 midbody diameter long; transverse vulva and rounded-conoid tail. Tylencholaimellus striatus Thorne, 1939 and T. projectus Siddiqi, 1964 are redescribed based on material collected from India. A diagnostic compendium of the genus Tylencholaimellus is also provided.
-
Three new and a known species of the genus Proleptonchus Lordello, 1955 (Nematoda: Leptonchidae) with a diagnostic compendium of the genus
Zootaxa, 2016Co-Authors: Sumaya Ahad, Wasim AhmadAbstract:This paper deals with the description of three new and one known species of the genus Proleptonchus Lordello, 1955. Proleptonchus kazirangus n. sp. from Kaziranga National Park, India is characterized by having 1.08–1.45 mm long body; cap-like, offset, lip region; 7–8 µm long odontostyle and 10–12 µm long Odontophore; short, pear-shaped pharyngeal bulb offset by a constriction, occupying about 18–21% of total neck length; female genital system mono-prodelphic; pars dilatata uteri with distinctly sclerotized central lumen containing refringent apophyses; posterior uterine sac 78–112 µm long, with sac-like structure representing a rudimentary oviduct; transverse vulva, short, rounded-conoid tail and males with 31–33 µm long spicules, lateral guiding pieces and seven, regularly spaced ventromedian supplements. P. prerectus n. sp. from Japan is characterized by having 1.18–1.43 mm long body; lip region cap-like, offset by a slight constriction; odontostyle 8 µm, Odontophore 9–10 µm; short cylindroid basal bulb offset by a constriction, occupying about 16–20% of total neck length; female genital system mono-prodelphic; pars dilatata uteri with sclerotized refringent apophyses; posterior uterine sac small, 27–36 µm; transverse vulva; a prerectal chamber and short, rounded-hemispheroid tail. P. japonicus n. sp. also from Japan is characterized by having 0.91–1.04 mm long body; lip region cap-like, set off by a slight constriction; odontostyle 5 µm and Odontophore 10–11 µm long; pharynx consists of a very slender, non-muscular anterior part, separated from pyriform basal bulb by a constriction, with thickened lumen in posterior region, occupying about 18–20% of total neck length; female genital system mono-prodelphic; posterior uterine sac small, 20–24 µm long; transverse vulva and short, rounded-conoid tail. P. shamimi Bajaj & Bhatti, 1980 is redescribed and its relationship with closely related species is discussed. A diagnostic compendium of all the valid species of Proleptonchus is also provided.
Patrick E Crago - One of the best experts on this subject based on the ideXlab platform.
-
The Journal of Experimental Biology 205, 3177–3206 (2002) Printed in Great Britain © The Company of Biologists Limited 2002
2008Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance image
-
Neural control exploits changing mechanical advantage and context dependence to generate different feeding responses in Aplysia
Biological Cybernetics, 2004Co-Authors: Gregory P. Sutton, David M Neustadter, Patrick E Crago, Elizabeth V Mangan, Randall D. Beer, Hillel J ChielAbstract:How does neural control reflect changes in mechanical advantage and muscle function? In the Aplysia feeding system a protractor muscle’s mechanical advantage decreases as it moves the structure that grasps food (the radula/Odontophore) in an anterior direction. In contrast, as the radula/Odontophore is moved forward, the jaw musculature’s mechanical advantage shifts so that it may act to assist forward movement of the radula/Odontophore instead of pushing it posteriorly. To test whether the jaw musculature’s context-dependent function can compensate for the falling mechanical advantage of the protractor muscle, we created a kinetic model of Aplysia ’s feeding apparatus. During biting, the model predicts that the reduction of the force in the protractor muscle I2 will prevent it from overcoming passive forces that resist the large anterior radula/Odontophore displacements observed during biting. To produce protractions of the magnitude observed during biting behaviors, the nervous system could increase I2’s contractile strength by neuromodulating I2, or it could recruit the I1/I3 jaw muscle complex. Driving the kinetic model with in vivo EMG and ENG predicts that, during biting, early activation of the context-dependent jaw muscle I1/I3 may assist in moving the radula/Odontophore anteriorly during the final phase of protraction. In contrast, during swallowing, later activation of I1/I3 causes it to act purely as a retractor. Shifting the timing of onset of I1/I3 activation allows the nervous system to use a mechanical equilibrium point that allows I1/I3 to act as a protractor rather than an equilibrium point that allows I1/I3 to act as a retractor. This use of equilibrium points may be similar to that proposed for vertebrate control of movement.
-
a kinematic model of swallowing in aplysia californica based on radula Odontophore kinematics and in vivo magnetic resonance images
The Journal of Experimental Biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
A kinematic model of swallowing in Aplysia californica based on radula/Odontophore kinematics and in vivo magnetic resonance images.
The Journal of experimental biology, 2002Co-Authors: David M Neustadter, Richard F Drushel, Patrick E Crago, Benjamin W Adams, Hillel J ChielAbstract:A kinematic model of the buccal mass of Aplysia californica during swallowing has been developed that incorporates the kinematics of the Odontophore, the muscular structure that underlies the pincer-like grasping structure, the radula. The model is based on real-time magnetic resonance images (MRIs) of the mid-sagittal cross section of the buccal mass during swallowing. Using kinematic relationships derived from isolated Odontophores induced to perform feeding-like movements, the model generates predictions about movement of the buccal mass in the medio-lateral dimension during the feeding cycle that are well-matched to corresponding coronal MRIs of the buccal mass during swallowing. The model successfully reproduces changes in the lengths of the intrinsic (I) buccal muscles I2 and I3 measured experimentally. The model predicts changes in the length of the radular opener muscle I7 throughout the swallowing cycle, generates hypotheses about the muscular basis of radular opening prior to the onset of forward rotation during swallowing and suggests possible context-dependent functions for the I7 muscle, the radular stalk and the I5 (ARC) muscle during radular opening and closing.
-
Radula-centric and Odontophore-centric kinematic models of swallowing in Aplysia californica.
The Journal of experimental biology, 2002Co-Authors: Richard F Drushel, David M Neustadter, Patrick E Crago, Benjamin W Adams, Greg P Sutton, Elizabeth V Mangan, Hillel J ChielAbstract:Two kinematic models of the radula/Odontophore of the marine mollusc Aplysia californica were created to characterize the movement of structures inside the buccal mass during the feeding cycle in vivo. Both models produce a continuous range of three-dimensional shape changes in the radula/Odontophore, but they are fundamentally different in construction. The radulacentric model treats the radular halves as rigid bodies that can pitch, yaw and roll relative to a fixed radular stalk, thus creating a three-dimensional shape. The Odontophore-centric model creates a globally convex solid representation of the radula/Odontophore directly, which then constrains the positions and shapes of internal structures. Both radula/Odontophore models are placed into a pre-existing kinematic model of the I1/I3 and I2 muscles to generate three-dimensional representations of the entire buccal mass. High-temporal-resolution, mid-sagittal magnetic resonance (MR) images of swallowing adults in vivo are used to provide non-invasive, artifact-free shape and position parameter inputs for the models. These images allow structures inside the buccal mass to be visualized directly, including the radula, radular stalk and lumen of the I1/I3 cavity. Both radula-centric and Odontophore-centric models were able to reproduce two-dimensional, mid-sagittal radula/Odontophore and buccal mass kinematics, but the Odontophore-centric model's predictions of I1/I3, I2 and I7 muscle dimensions more accurately matched data from MR-imaged adults and transilluminated juveniles.
