Faculty
1. Ram Lakhan Pandey Vimal
Professor (Research)
I am the Amarāvati-Hīrāmaṇi Professor (Research) at Vision Research Institute (USA) and Dristi Anusandhana Sansthana (India). After completing B.E. (Electrical Engg.) at M.A.C.T. Bhopal and Part I of M.Tech. at I.I.T. Kanpur in India, I moved to USA to do M.S. (Computer Science) at Iowa State University, Ph.D. (Biophysics) at University of Illinois, and postdoctoral fellowship in color vision psychophysics at University of Chicago. Further researches in visual psychophysics, neuroscience, and fMRI were at York University (Canada), New England College of Optometry (Boston), and Harvard Medical Schools (Schepens Eye Research Institute and McLean Hospital).
2. Vivekanand Pandey Vimal
Assistant Professor (Research)
Introduction
Vivek is a Postdoctoral Fellow in Space Health funded by the Translational Research Institute and conducts research in the Ashton Graybiel Spatial Orientation Lab.
Our objective was to examine how the control of orientation is learned in a task involving dynamically balancing about an unstable equilibrium point, the gravitational vertical, in the absence of leg reflexes and muscle stiffness. Subjects (n = 10) used a joystick to set themselves to the gravitational vertical while seated in a multi-axis rotation system (MARS) device programmed with inverted pendulum dynamics. The MARS is driven by powerful servomotors and can faithfully follow joystick commands up to 2.5 Hz with a 30-ms latency. To make the task extremely difficult, the pendulum constant was set to 600°/s2. Each subject participated in five blocks of four trials, with a trial ending after a cumulative 100 s of balancing, excluding reset times when a subject lost control. To characterize performance and learning, we used metrics derived from joystick movements, phase portraits (joystick deflections vs MARS position and MARS velocity vs angular position), and stabilogram diffusion functions. We found that as subjects improved their balancing performance, they did so by making fewer destabilizing joystick movements and reducing the number and duration of joystick commands. The control strategy they acquired involved making more persistent short-term joystick movements, waiting longer before making changes to ongoing motion, and only intervening intermittently.
We determined the relative contributions of gravity-dependent positional cues and motion cues to the learning of roll balance control. We hypothesized that gravity-dependent otolith and somatosensory shear forces related to body orientation would yield better initial performance, more rapid learning, and better retention. Blindfolded subjects rode in a device programmed to roll with inverted pendulum dynamics in a vertical (UPRIGHT) or horizontal plane (SUPINE), and used a joystick to align themselves with the direction of balance. Each subject completed five blocks of four 100 s long trials on two consecutive days in one of four groups (n = 10 per group): Group 1, UPRIGHT balancing both days; Group 2, SUPINE both days; Group 3, UPRIGHT then SUPINE; and Group 4, SUPINE then UPRIGHT. On Day 1, UPRIGHT subjects showed better initial performance and greater improvement in performance than SUPINE subjects, who showed improvements only in having fewer deviations exceeding ±60 deg from the direction of balance. Subjects tested UPRIGHT on both days showed full retention of learning across days and additional Day 2 learning, but subjects tested SUPINE on both days showed partial retention of their marginal learning from Day 1 and little improvement on Day 2. Subjects tested SUPINE on Day 2 after being tested UPRIGHT on Day 1 showed no better performance than subjects tested SUPINE on Day 1. By contrast, there was transfer from SUPINE on Day 1 to UPRIGHT on Day 2. We conclude that absence of gravitationally dependent otolith and somatosensory cues degrades balance performance.
To investigate the role of gravitational cues in the learning of a dynamic balancing task, we placed blindfolded subjects in a device programmed with inverted pendulum dynamics about the yaw axis. Subjects used a joystick to try and maintain a stable orientation at the direction of balance during 20 100 s-long trials. They pressed a trigger button on the joystick to indicate whenever they felt at the direction of balance. Three groups of ten subjects each participated. One group balanced with their body and the yaw axis vertical, and thus did not have gravitational cues to help them to determine their angular position. They showed minimal learning, inaccurate indications of the direction of balance, and a characteristic pattern of positional drifting away from the balance point. A second group balanced with the yaw axis pitched 45° from the gravitational vertical and had gravity relevant position cues. The third group balanced with their yaw axis horizontal where they had gravity-dependent cues about body position in yaw. Groups 2 and 3 showed better initial balancing performance and more learning across trials than Group 1. These results indicate that in the absence of vision, the integration of transient semicircular canal and somatosensory signals about angular acceleration is insufficient for determining angular position during dynamic balancing; direct position-dependent gravity cues are necessary.
3. Manju-Uma C. Pandey-Vimal
Assistant Professor (Research)
(details are in developmental phase)
4. István Bókkon
Professor (Research)
(details are in developmental phase)
5. Nadeem Haque
Assistant Professor (Research)
haque_nadeem@hotmail.com
(details are in developmental phase)