2013 Participants
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NAME: Sumaiya Chaudhry

PROJECT TITLE: Detecting Forces in a Reference Frame

In all animals, forces must be generated by limb muscles in specific directions and magnitudes in posture and locomotion. However, it is not clear how sensory information about muscle force is organized and integrated in limb control.   Our previous studies have shown that, in insects, receptors that monitor forces via cuticular strains (trochanteral campaniform sensilla) signal muscle forces and loads in a specific frame of reference, the plane of movement of the major intrinsic leg joints. In the present studies, we will test whether responses and motor effects of another group of sense organs (tarsal campaniform sensilla) are related to the same reference frame. We will characterize the morphology and cuticular specializations of the receptors by confocal microscopy.  We will also study responses of the sense organs in physiological experiments.  Activities of sensory units will be monitored extracellularly. Loads will be applied to the tarsus in different directions.  We will generate data on the mean firing frequencies, rate, and amplitude sensitivities in each direction.  These findings will test whether the responses of the sense organs are maximal in the plane of tarsal movement.  They will also test the idea that campaniform sensilla provide information about loads as the resistance to muscle tensions, similar to vertebrate Golgi tendon organs. These finding are important and generally applicable as the organization of force information within a reference frame can simplify control of synergist muscles and optimization of leg use.

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