Meeting Abstract

P2.113  Sunday, Jan. 5 15:30  Analog versus digitial signalling in motor control systems BELANGER, JH*; PARIKSHAK, H; West Virginia University; West Virginia University jim.belanger@mail.wvu.edu

There is considerable interest in using biological systems to explore the relative capabilities of analog versus digital signaling, particularly the differences between the two modes in terms of information transfer capability and energy efficiency under different conditions. Much research has focused on these issues using sensory systems as the focus, but there has been little to no exploration of these issues in motor systems. This is somewhat surprising, particularly given that vertebrate and arthropod motor systems operate quite differently when examined in this context. In mammalian systems, motor information is passed on in a primarily digital form (frequency coding by action potentials) from the level of the motor neurons forward. Each element in the path (neuromuscular junction, muscle membrane, calcium release from the sarcoplasmic reticulum, contractile proteins) is functioning primarily as a “dumb” follower element, doing little in the way of integration. In contrast, motor commands in arthropod systems are passed in a much more analog form, with integration taking place at several steps along the way. The parsimonious explanation for these differences seems to be that arthropods use analog coding and peripheral modulation to achieve the flexibility and dynamic range for which vertebrates use motor unit recruitment. In order to explore this issue, we are examining the control properties of the two systems, using data from both physiological and simulation experiments. Clearly, there are many places where we can look for useful differences between the two systems. As a start, we have begun using tools from control theory (Bode plots, information transfer rates) to analyze the relative capabilities (and limitations) of the two systems.