The aim of the proposed research is to determine how three cortical areas in the primate contribute to the generation of visually guided saccadic eye movements: the frontal eye fields, the medial eye fields and the lateral intraparietal sulcus. The experiments we propose are designed to assess: (1) How the signals from the cortex reach the brainstem oculomotor centers, (2) how excitatory and inhibitory circuits in these three areas mediate eye-movement control, and (3) the extent to which the three areas are also involved in eye/hand coordination. Three sets of experiments are planned: Experiment 1 will determine whether in the intact animal saccadic eye-movement generation is achieved through two parallel channels, the anterior and the posterior, as we had hypothesized in our earlier long-term lesion studies. To determine whether these two pathways are functional in the intact animal, the effects of electrical stimulation of the frontal eye fields and medial eye fields will be studied using short-term unilateral and bilateral reversible inactivation of the superior colliculus. Experiment 2 will assess the role excitatory and inhibitory neuronal circuits play in the frontal eye fields, the medial eye fields and the lateral intraparietal sulcus in eye movement control. To accomplish this, the generation of eye movements will be studied in a series of behavioral tasks when these areas are infused with briefly acting agonists and antagonists of glutamate and GABA. Experiment 3 will determine the extent to which these three areas contribute to eye/hand coordination in addition to saccadic eye-movement generation. Performance on eye/hand coordination tasks will be assessed before, during and after local infusions of reversible blocking agents. The results obtained from the proposed experiments should have significant implications for the treatment of eye-movement disorders. If in the intact organism the anterior and posterior streams, as had been proposed in our earlier work, are indeed functional, as to be determined in the first set of experiments in this series, more effective treatment routines can be devised than if all cortical commands to move the eyes traverse through the superior colliculus.
| Tehovnik, Edward J; Slocum, Warren M; Smirnakis, Stelios M et al. (2009) Microstimulation of visual cortex to restore vision. Prog Brain Res 175:347-75 |
| Zhang, Ying; Schiller, Peter H (2008) The effect of overall stimulus velocity on motion parallax. Vis Neurosci 25:3-15 |
| Schiller, Peter H; Slocum, Warren M; Weiner, Veronica S (2007) How the parallel channels of the retina contribute to depth processing. Eur J Neurosci 26:1307-21 |
| Zhang, Ying; Weiner, Veronica S; Slocum, Warren M et al. (2007) Depth from shading and disparity in humans and monkeys. Vis Neurosci 24:207-15 |
| Tehovnik, Edward J; Slocum, Warren M (2007) What delay fields tell us about striate cortex. J Neurophysiol 98:559-76 |
| Chen, L Longtang; Tehovnik, Edward J (2007) Cortical control of eye and head movements: integration of movements and percepts. Eur J Neurosci 25:1253-64 |
| Schiller, Peter H; Carvey, Christina E (2006) Demonstrations of spatiotemporal integration and what they tell us about the visual system. Perception 35:1521-55 |
| Tehovnik, E J; Tolias, A S; Sultan, F et al. (2006) Direct and indirect activation of cortical neurons by electrical microstimulation. J Neurophysiol 96:512-21 |
| Schiller, Peter H; Haushofer, Johannes (2005) What is the coordinate frame utilized for the generation of express saccades in monkeys? Exp Brain Res 167:178-86 |
| Tehovnik, E J; Slocum, W M; Carvey, C E et al. (2005) Phosphene induction and the generation of saccadic eye movements by striate cortex. J Neurophysiol 93:1-19 |
Showing the most recent 10 out of 39 publications
