Previous Research Projects
Neural Control of Coordinated Movements
In order to interact with objects in our environment we must be able to gather accurate sensory information about our surroundings, distinguish our movements from the movements of objects in the world, and coordinate our own movements in order to orient, and navigate smoothly through a complex environment. In my lab we study the neural control of coordinated orienting behaviors including gaze shifts and pursuit of stationary and moving targets in the head-unrestrained subject. We seek to understand the roles of neurons in the brainstem, cerebellum and cortex in generating and executing these movements within the context of testing critical predictions of models (i.e. hypotheses) of these critical sensorimotor control systems.
Electrical stimulation of the Nucleus Reticularis Gigantocellularis
Electrical stimulation of the Nucleus Reticularis Gigantocellularis was used to test the predictions of a gaze model (Freedman 2001. Biol. Cybern. 84: 453–462).
On the left simulations of eye (A), gaze (B) and head (C) velocity are shown during
control movements (orange) and during simulated NRG stimulation (blue). On the right, mean (+/- SD) eye (D), gaze (E), and head (F) velocity are plotted as functions of time for two sets of movements: Control gaze shifts to briefly flashed visual targets (orange), and similar trials during which the right NRG was electrically stimulated. Data were consistent with the predictions of the model.
- Freedman, E.G., and Quessy, S. Electrical stimulation of rhesus monkey nucleus reticularis gigantocellularis: II. Effects on metrics and kinematics of ongoing gaze shifts to visual targets. Exp. Brain Res. 156:357-376, 2004
- Quessy, S. and Freedman, E.G. Electrical stimulation of rhesus monkey nucleus reticularis gigantocellularis: I. Characteristics of evoked head movements. Exp. Brain Res. 156:342-356, 2004