Kinematics of the buccal mass during swallowing based on magnetic resonance imaging in intact, behaving Aplysia californica

2002 ◽  
Vol 205 (7) ◽  
pp. 939-958 ◽  
Author(s):  
David M. Neustadter ◽  
Richard F. Drushel ◽  
Hillel J. Chiel
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Neural Control ◽  
Aplysia Californica ◽  
Resonance Imaging ◽  
Large Variability ◽  
Marine Mollusc ◽  
Buccal Mass ◽  
Internal Structures ◽  
Freely Moving

SUMMARY 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.

Kinematic models of the buccal mass of Aplysia californica.

1998 ◽  
Vol 201 (10) ◽  
pp. 1563-1583 ◽  
Author(s):  
R F Drushel ◽  
D M Neustadter ◽  
I Hurwitz ◽  
P E Crago ◽  
H J Chiel
Keyword(s):  
Neural Control ◽  
Kinematic Model ◽  
Aplysia Californica ◽  
Relative Location ◽  
Marine Mollusc ◽  
Buccal Mass ◽  
Kinematic Models ◽  
Made In

The feeding behavior of the marine mollusc Aplysia californica is an intensively studied model system for understanding the neural control of behavior. Feeding movements are generated by contractions of the muscles of the buccal mass. These muscles are internal and cannot be visualized during behavior. In order to infer the movements of the muscles of the buccal mass, two kinematic models were constructed. The first kinematic model assumed that the complex consisting of the pincer-like radula and the underlying odontophore was spherical in shape. In this model, the radula/odontophore was moved anteriorly or posteriorly and the more superficial buccal muscles (I1/I3 and I2) were fitted around it. Although the overall buccal mass shapes predicted by this model were similar to those observed in vivo during protraction, the shapes predicted during retraction were very different. We therefore constructed a second kinematic model in which the shape of the radula/odontophore was based on the shapes assumed by those structures in vitro when they were passively forced into protraction, rest or retraction positions. As each of these shapes was rotated, the second kinematic model generated overall shapes of the buccal mass that were similar to those observed in vivo during swallowing and tearing, and made predictions about the antero-posterior length of the buccal mass and the relative location of the lateral groove. These predictions were consistent with observations made in vivo and in vitro. The kinematic patterns of intrinsic buccal muscles I1 and I2 in vivo were estimated using the second model. Both models make testable predictions with regard to the functions and neural control of intrinsic buccal muscles I2 and I3.

Magnetic Resonance Imaging of Vascular Lesions in Children

1984 ◽  
Vol 25 (6) ◽  
pp. 449-456 ◽  
Author(s):  
H. G. Ringertz ◽  
R. C. Brasch ◽  
A. Brody ◽  
R. Ehman ◽  
C. A. Gooding
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Vascular Lesions ◽  
Vascular Tumors ◽  
Resonance Imaging ◽  
Vascular Abnormalities ◽  
Non Invasive ◽  
Internal Structures ◽  
The Status ◽  
Magnetic Resonance Imaging Mri

Ten children aged 1 week to 13 years with 12 vascular abnormalities were examined with magnetic resonance imaging (MRI) and other imaging modalities. MRI was the only single non-invasive modality that demonstrated all lesions and their internal structures. The vascular nature of 3 hemangiomas could not be established with MRI alone. No marked differences in MRI appearance was seen in 5 cases with vascular tumors compared with 5 cases with other vascular abnormalities. The status of the blood in the vascular lesions as flowing fast, slow, or not at all was successfully assessed in 9 of the 12 lesions.

Magnetic Resonance Imaging of Human Extraocular Muscles in Convergence

2003 ◽  
Vol 89 (4) ◽  
pp. 2072-2085 ◽  
Author(s):  
Joseph L. Demer ◽  
Reika Kono ◽  
Weldon Wright
Keyword(s):  
Magnetic Resonance Imaging ◽  
Young Adults ◽  
Magnetic Resonance ◽  
Cross Section ◽  
Cross Sections ◽  
Single Unit ◽  
Neural Control ◽  
Resonance Imaging ◽  
Contrast Enhanced ◽  
Superior Oblique

Extraocular muscle (EOM) paths during asymmetrical convergence were evaluated by tri-planar, contrast-enhanced magnetic resonance imaging of the orbits of eight young adults during binocular fixation of a target aligned to one eye at 800 and 15 cm distance. Cross sections and paths of EOMs were determined from area centroids. In convergence, the aligned eye rotated and translated negligibly, while its inferior oblique (IO) muscle exhibited significant contractile thickening. There were no significant contractile changes in the cross sections of aligned eye rectus or superior oblique (SO) muscles in convergence. The converging eye rotated nasally 22.4° but translated negligibly. The converging eye medial (MR) and lateral rectus (LR) muscles exhibited large contractile cross-section changes, and the IO showed significant contractile thickening, while the vertical rectus muscles and the SO did not. Anterior paths of three aligned eye rectus EOMs could be determined in convergence and shifted consistent with a 1.9° extorsion of the rectus pulley array. Such extorsional reconfiguration of the rectus pulleys would move the pulleys in coordination with globe extorsion and avoid imparting torsional action to these EOMs. Extorsional rectus pulley shift in convergence is inconsistent with the reconfiguration predicted to explain the temporal tilting of Listing's planes, instead suggesting that this temporal tilting is due to variations in oblique EOM innervation. Absence of globe translation in convergence argues against overall EOM co-contraction. The reconfiguration of EOM geometry in convergence has important implications for single-unit studies of neural control.

scholarly journals 3-Dimensional magnetic resonance imaging of the freely moving human eye

2020 ◽  
Vol 194 ◽  
pp. 101885 ◽  
Author(s):  
Benedetta Franceschiello ◽  
Lorenzo Di Sopra ◽  
Astrid Minier ◽  
Silvio Ionta ◽  
David Zeugin ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Resonance Imaging ◽  
3 Dimensional ◽  
Human Eye ◽  
Freely Moving

Functional information from magnetic resonance imaging

1995 ◽  
Vol 53 ◽  
pp. 84-85
Author(s):  
Alan P. Koretsky ◽  
Afonso Costa e Silva ◽  
Yi-Jen Lin
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Cancer Biology ◽  
Imaging Modality ◽  
Magnetic Resonance Images ◽  
Great Success ◽  
Functional Information ◽  
Resonance Imaging ◽  
High Resolution Mri

Magnetic resonance imaging (MRI) has become established as an important imaging modality for the clinical management of disease. This is primarily due to the great tissue contrast inherent in magnetic resonance images of normal and diseased organs. Due to the wide availability of high field magnets and the ability to generate large and rapidly switched magnetic field gradients there is growing interest in applying high resolution MRI to obtain microscopic information. This symposium on MRI microscopy highlights new developments that are leading to increased resolution. The application of high resolution MRI to significant problems in developmental biology and cancer biology will illustrate the potential of these techniques.In combination with a growing interest in obtaining high resolution MRI there is also a growing interest in obtaining functional information from MRI. The great success of MRI in clinical applications is due to the inherent contrast obtained from different tissues leading to anatomical information.

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