EPSCoR: Ionic Currents in Vestibular Hair Cells.
[No authors listed]
UIID-NSF: 1505
Abstract
The sense of balance and equilibrium in vertebrates is provided by the vestibular system, which functions to maintain the position of the body in space and to stabilize the visual image on the retina. The semicircular canal system, the subject of the research proposed here, is the vestibular end organ responsible for sensing angular acceleration of the head and transmitting this information to the central nervous system. Unlike many other sensory systems, for example, the visual system, our knowledge of even basic properties of the vestibular system is still very rudimentary, primarily because in higher animals, this system is encased in the hard temporal bone of the head. Recent technical advances have made it possible to isolate neurons individually from this system and record their responses to sensory stimulation. These experiments address the need for advancement in this field of research using some of this new technology. Central to this study is the choice of an experimental animal in which the vestibular system can be easily accessed. In higher vertebrates, in addition to the cost of the research animals and concerns over the use of more evolved vertebrates, the vestibular system is encased in the very dense temporal bone. On the other hand, this end organ in fish is a highly evolved system without the dense temporal bone and thus offers a unique opportunity for study of basic properties of the coding of movement. The fish has therefore been used as a model system to study vestibular processing for over 20 years. The experiments described in this research proposal will be carried out using the toadfish, Opsanus tau, as the experimental animal. In the toadfish in particular, there is easy access to the canals due to the flat head of the fish and hence, this animal has been used extensively to study the process of sensory coding of head and body movement by the semicircular canals. In the past, this research has centered primarily on recording from the most easily accessible nerve fibers. The neural response recorded from these nerve fibers that transmit sensory information from the primary sensory receptor, the hair cell, to the midbrain is complex. This complexity may be due to differences in the properties of several levels of the peripheral vestibular system. The research proposed here is the investigation of the ionic currents of the primary sensory cell responsible for sensing body and head movement. Progress in understanding these currents, as opposed to work from other levels of the vestibular system, has only come about in recent years with the development of a particular technique known as patch clamp recording technology and the use of isolated sensory cells. In the experiments proposed here, the semicircular canals will be removed from the animal and the sensory cells mechanically removed as isolated cells. Patch clamp technology will then be used to record ionic currents from the sensory cells. These currents will be separated and classified using known voltage paradigms and pharmacology to provide a quantitative description of the behavior of the currents as they code the information on body and head motion. The data obtained will be incorporated with that from other levels of the system, either currently available or in the process of experimental investigation in other laboratories, to obtain a more comprehensive knowledge of sensory processing in the vestibular system. Incorporation of these data into a computer generated mathematical model of the semicircular canal system is planned for the future. Not only do the proposed experiments enlarge our basic understanding of vestibular system function but also they provide knowledge vital to science and medicine in arriving at the mechanisms underlying pathology of the vestibular system, such as vertigo, motion sickness and the problems of balance and equilibrium so common in the aging human population.
Other Details
- Award Instrument: Standard Grant
- Email: [email protected]
- Organization: University of Puerto Rico Medical Sciences Campus
- Other Investigators: David Jacobs, Jill Gemmill
- Primary Investigator: Antoinette Steinacker
- Program(s): SENSORY SYSTEMS, EXP PROG TO STIM COMP RES
- Start Date: 08/01/2000
