1985 — 1993 |
Weiss, Thomas F |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Experimental-Theoretical Studies of Cochlear Mechanisms @ Massachusetts Institute of Technology
Our overall goal is to understand the operation of the cochlea, in particular the mechanisms through which mechanical signals that enter the cochlea lead to the discharge of nerve fibers that leave the cochlea and enter the brain. We measure physiological variables at key stages in the cochleae of anesthetized alligator lizards and relate these through theoretical models of the underlying mechanisms. Much information has already been obtained on the alligator lizard car: the anatomy is well-described; measurements have been made of the mechanics of the middle and inner ear, the motion of the stereocilia, the receptor potentials of hair cells, the responses of supporting cells, the electromechanical environment of the receptor organ, and the spike discharges of cochlear nerve fibers. In this application, we propose a combined experimental and theoretical investigation of this ear with the aim of formulating a comprehensive model relating the sound pressure at the tympanic membrane to the discharges of cochlear nerve fibers in terms of the underlying structures and mechanisms. Many of these structures and mechanisms are common to all vertebrates. Hence, our findings should have general significance for understanding cochlear processes. Because our present understanding of cochlear processes is so incomplete, diagnosis and treatment of hearing impairments of cochlear origin are often purely empirical. More useful management of cochlear dysfunction will evolve when we have a clearer understanding of normal cochlear mechanisms.
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1988 — 1992 |
Weiss, Thomas F |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Theory of Fluid Mechanical Stimulation of Hair Cells @ Massachusetts Institute of Technology
The sensory receptor (hair) cells of auditory, vesibular and lateral-line organs are stimulated by displacements of bundles of sensory hairs that protrude from the cells' surfaces. Experiments show that the mechanics of hair bundle motion plays a key role in sensory reception in these systems, and hence, in the processes of hearing and equilibrium. Our goal is to understand the motions of hair bundles in terms of underlying physical mechanisms. In this application, we propose theoretical studies to assess how the motion of hair bundles is affected by: (1) cochlear fluids; (2) hydrodynamic coupling to nearby structures (such as the tectorial membrane and the surface of sensory epithelium); (3) hydrodynamic interactions with neighboring hair bundles; (4) the shape of the hair bundle; (5) mechanical properties of hair bundles, the tectorial membrane, and the sensory epithelium. The proposed theoretical studies will involve both mathematical analysis and numerical studies using a variety of digital computers (including personal computers, minicomputers, as well as supercomputers). Our approach is to examine solutions of the equations of fluid motion for a succession of geometries each designed to reveal the role of a key structural feature of hair cell organs.
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1994 |
Weiss, Thomas F |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Experimental Theoretical Studies of Cochlear Mechanisms @ Massachusetts Institute of Technology
Our overall goal is to understand the operation of the cochlea, in particular the mechanisms through which mechanical signals that enter the cochlea lead to the discharge of nerve fibers that leave the cochlea and enter the brain. We measure physiological variables at key stages in the cochleae of anesthetized alligator lizards and relate these through theoretical models of the underlying mechanisms. Much information has already been obtained on the alligator lizard car: the anatomy is well-described; measurements have been made of the mechanics of the middle and inner ear, the motion of the stereocilia, the receptor potentials of hair cells, the responses of supporting cells, the electromechanical environment of the receptor organ, and the spike discharges of cochlear nerve fibers. In this application, we propose a combined experimental and theoretical investigation of this ear with the aim of formulating a comprehensive model relating the sound pressure at the tympanic membrane to the discharges of cochlear nerve fibers in terms of the underlying structures and mechanisms. Many of these structures and mechanisms are common to all vertebrates. Hence, our findings should have general significance for understanding cochlear processes. Because our present understanding of cochlear processes is so incomplete, diagnosis and treatment of hearing impairments of cochlear origin are often purely empirical. More useful management of cochlear dysfunction will evolve when we have a clearer understanding of normal cochlear mechanisms.
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1995 — 1999 |
Weiss, Thomas |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Development of Educational Software For Cellular Biophysics @ Massachusetts Institute of Technology
Thomas F. Weiss DUE 9455337 Massachusetts Institute of Technology FY1995 $ 150,000 Cambridge , MA 021394307 Course and Curriculum Life Sciences Title: Cellular Biophysics Software The purpose of this project is to make educational software and methodologies for its use in teaching cellular biophysics widely available. Software has been used for 10 years to teach cellular biophysics to juniors majoring in engineering and science at MIT. The software is used in lecture demonstrations, special recitation classes held in electronic classrooms, as a basis of homework assignments, and for more intensive research projects defined by students. Use of the software has greatly enhanced students' interest in and comprehension of topics in cellular biophysics. All the software has been developed by student programmers and is currently available only on UNIX workstations at MIT. The software is written in C and XWindows. In the current project undergraduates and graduate students are converting this software to run under a vendor distributed computation and visualization software package (MAT LAB) which is available on all the common computer platforms including Macintoshes, PCs running Microsoft Windows, and UNIX workstations running XWindows. The conversion allows students and instructors to more readily customize the software for their own use, and greatly facilitates software maintenance for faculty. A software textbook is being published and distributed with floppy disks of the software. The software and software textbook will be companions to a new textbook on cellular biophysics that is in preparation. The combination should provide a new set of educational materials for teaching cellular biophysics to students in engineering and science. The approach is to provide rigorous, in-depth mathematical treatments as well as the e mpirical basis of important biological, chemical, and physical principles of cell biophysics. The software together with the software text allows students and faculty to explore these principles in new ways.
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0.915 |
1995 — 1996 |
Weiss, Thomas F |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Experimental/Theoretical Studies of Cochlear Mechanisms @ Massachusetts Institute of Technology
The overall goal of the proposed research is to understand how inner ear mechanisms determine the neural code that relates sounds to nerve messages that enter the brain. Knowledge of these mechanisms is important for several reasons: (1) Determining the bases of the code is an intrinsically interesting scientific problem involving integrated knowledge of mechanical, electrical, biological and chemical processes at organ, cellular, membrane, and molecular levels all focussed on understanding the role of the inner ear in hearing. (2) The results should have significance for sensory reception, in general, for mechanoreception in particular, and especially for understanding the acoustico-lateralis systems which include the lateral-line organs found in fish and amphibia as well as vestibular and auditory organs found in all vertebrates. (3) The practical benefits of this knowledge should also include more precise delineation of inner ear disorders, suggestions for treatment, development of prosthetic devices, and incorporation of knowledge of inner-ear processing into the design of systems for processing speech. The specific objective for the proposed grant period is to understand the mechanical processes in the cochlea that link sound-induced motion of the receptor organ to motion of its constituent structures, including the tectorial membrane, the hair bundles of hair cells, and the individual stereocilia that make up a hair bundle. The material properties (including osmotic, mechanical, and electrical properties) of the tectorial membrane will be measured in both isolated tectorial membrane preparations (in the mouse, chick, and the alligator lizard) and in an in vitro preparation of the alligator lizard cochlea. The relations among the sound-induced motion of the receptor organ, tectorial membrane, hair bundles of hair cells, and individual stereocilia in a hair bundle will be investigated using video microscopy of an in vitro preparation of the alligator lizard cochlea.
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