Research in the Ashton Graybiel Spatial Orientation Laboratory covers human spatial orientation, motor control, and adaptation in unusual force and sensory environments. Understanding basic mechanisms and their practical implications are both of interest. Basic mechanisms are investigated from biomechanical, neuromotor, and computational perspectives. Unique experimental approaches include 1) emphasis on intersensory and sensory-motor interactions, 2) recognition of the intimate relationship between moment-to-moment control and long-term adaptation, and 3) exploitation of non-terrestrial conditions, such as space flight, artificial gravity and virtual environments and of clinical conditions.
Our research on control of reaching movements illustrates these themes. A traditional experimental approach to studying reaching movements involves unexpectedly perturbing movement trajectories and observing the resulting errors. We have developed a new perturbation paradigm employing a rotating room facility located in our laboratory that simulates an "artificial gravity" environment.
Our paradigm involves comparing movements made in a normal stationary environment to ones made in the rotating room. The centrifugal force field generated during rotation may be similar enough to the terrestrial gravitational field for a rotating space vehicle to be used for generating "artificial gravity". However, rotation also leads to Coriolis forces that are a potential source of side effects that could prohibit the use of rotation for artificial gravity. For example, reaching movements made in a rotating room generate Coriolis forces on the reaching arm that are directly proportional to the cross product of the room's angular velocity and the arm's linear velocity within the room. Our research has investigated the implications of Coriolis force perturbations for astronaut performance and health during long duration space missions in a rotating space vehicle, and we have also made use of the Coriolis force perturbations for basic research.
Coriolis force perturbations in the rotating room are transient (only present when the arm is moving), unexpected and unique because they act without local contact. We have found that reaching movements are deviated in endpoint and path in the direction of Coriolis forces in the rotating room, whereas techniques that apply movement-contingent contacting perturbations do not lead to endpoint errors. Adaption to Coriolis forces occurs within 10-20 movements such that straight, accurate reaches are again possible, and mirror-image aftereffects occur when rotation stops. The pattern of findings has shown that 1) the field of candidate control variables for movement execution does not include muscle stiffness, 2) proprioception is paramount in trajectory monitoring and adaptation, 3) the relevant proprioceptive information includes a strong cutaneous component in addition to muscle spindle, joint and tendon signals, 4) cutaneous inputs from perturbations during movement execution are utilized in different ways from cutaneous signals generated by contact with surfaces at movement termination, 5) posture and movement involve separate control elements, 6) the nervous system represents and utilizes detailed "expectations" about the forces that will be encountered during a reaching movement, and 7) the movement plan is more dynamic than previously assumed.
One of the most important and unexpected advances resulting from our studies of the effects of Coriolis forces in the rotating room is the realization that Coriolis forces and Coriolis-like forces are ubiquitous in the normal movements that we make in everyday life. This has opened new avenues for investigating coordination of multi-joint posture and movement.
Other problems being actively investigated include 1) the role of Coriolis and other unusual forces in eye-head coordination and calibration, 2) vestibular, and proprioceptive influences on visual and auditory localization, 3) haptic, visual, auditory and vestibular factors in perceived body orientation, position sense, static posture and locomotion, 4) causes and ways of alleviating motion sickness disorientation and misorientation in space flight, artificial gravity and virtual environments.
Lackner JR & DiZio P (2009) Angular displacement perception modulated by force background. Experimental Brain Research 195(2):335-343.
Lackner JR & DiZio P (2009) Control and calibration of multi-segment reaching movements. Advances in Experimental Medicine and Biology 629:681-698.
Bortolami SB, Inglis JT, Castellani S, DiZio P, & Lackner J (2010) Influence of galvanic vestibular stimulation on postural recovery during sudden falls. Experimental Brain Research 205(1):123-129.
Lackner JR & DiZio P (2010) Audiogravic and oculogravic illusions represent a unified spatial remapping. Experimental Brain Research 202:513-518.
Carriot J, Bryan A, DiZio P, & Lackner JR (2011) The oculogyral illusion: retinal and oculomotor factors. Experimental Brain Research 209(3):415-423.
Piovesan D, Pierobon A, DiZio P, & Lackner J (2011) Comparative analysis of methods for estimating arm segment parameters and joint torques from inverse dynamics. Journal of Biomechanical Engineering 133(3).
Piovesan D, Pierobon A, DiZio P, & Lackner JR (2012) Measuring Multi-Joint Stiffness during Single Movements: Numerical Validation of a Novel Time-Frequency Approach. PLoS One 7(3).
Pigeon P, DiZio P, & Lackner JR (2013) Immediate compensation for variations in self-generated Coriolis torques related to body dynamics and carried objects. J. Neurophysiol. 110(6):1370-1384.
Piovesan D, Pierobon A, DiZio P, & Lackner JR (2013) Experimental measure of arm stiffness during single reaching movements with a time-frequency analysis. J. Neurophysiol. 110(10):2484-2496.
Bakshi A, DiZio P, & Lackner JR (2014) Statistical analysis of quiet stance sway in 2-D. Experimental Brain Research 232(4):1095-1108.
Bakshi A, Ventura J, DiZio P, & Lackner JR (2014) Adaptation to Coriolis perturbations of voluntary body sway transfers to preprogrammed fall-recovery behavior. J. Neurophysiol. 111(5):977-983.
Last review: November 12, 2014