Selection and generation of limb movements by a combination of multifunctional and specialized spinal interneurons.

[No authors listed]

UIID-NSF: 297

Abstract

Ari Berkowitz Proposal #0950370 Selection and generation of limb movements by a combination of multifunctional and specialized spinal interneurons. Animals and people must constantly decide how to move their limbs. They often do so without conscious awareness. Their nervous systems are responsible for making and implementing decisions about limb movements that are appropriate for each situation. The turtle spinal cord is an excellent model system to investigate how this is done. The turtle spinal cord can appropriately produce several types of swimming, scratching, and limb withdrawal movements, even without input from the brain, essentially using programs that are stored within networks of spinal cord interneurons. (Interneurons are the nerve cells in between sensory neurons and motor neurons; motor neurons excite muscles to contract.) Turtles are also easier to study physiologically than mammals because their tissues remain healthy in physiologically challenging conditions. This project will use electrophysiological, anatomical, immunocytochemical, and pharmacological methods to study two types of spinal cord interneurons previously identified by this group of researchers. Interneurons of one type, called transverse interneurons, are active during several kinds of limb movements, and thus are multifunctional. Interneurons of the other type, called scratch-specialized interneurons, are activated during scratching but are often inhibited during swimming. For each type of interneuron, this project will determine which neurotransmitter(s) the interneurons use, and therefore whether they are excitatory or inhibitory; the project will also determine which neurotransmitter inhibits scratch-specialized interneurons during swimming. Finally, the project will determine whether interneurons of each type directly contact motor neurons. This project will thus test specific hypotheses about how neuronal networks combine multifunctional and specialized interneurons to select and generate limb movements. The project may reveal mechanisms that nervous systems use to make and implement movement decisions, not only in turtles but in vertebrates generally. This project will also provide training to two graduate students and to undergraduates in electrophysiological, anatomical, pharmacological, and general scientific approaches.

Other Details

• Award Instrument: Continuing grant
• Email: [email protected]
• Organization: University of Oklahoma Norman Campus
• Other Investigators: Barbara Bannatyne, David Maxwell
• Primary Investigator: Ari Berkowitz
• Program(s): ACTIVATION, MODULATION
• Start Date: 04/15/2010