Edward L. Keller

Research Interests

Neurophysiol of the oculomotor system, visual-vestibular interactions, models of motor systems, parallel processing for motion detectors.

Research Summary

Neurodynamics of Large Enaembles of Nerrve Cells in Motor Control: The objective of this research is to provide a better understanding of the distributed spatio-temporal neural processing that underlies the control of saccadic eye movements. Studies are focused at the present time on the primate superior colliculus, a layered and topographically mapped neural structure that receives direct retinal input and sends its outputs to motor regions in the brain stem controlling the oculomotor system. We record single neurons in the alert behaving monkey trained to make saccadic eye movements under a variety of conditions. We also construct neural network models to help us explain the complex neural data that we have recorded. In a recent version of the model, the superior colliculus(SC) is represented by two layers of cells. Simulated visual inputs ativate the upper layer which is connected to the lower (motor) layer with feedforward projections. Extensive lateral interconnections exist in the motor layer. The weights assigned in these interconnections are established with a recurrent backpropagation algorithm and by training on a set of activity patterns obtained from neurons recorded in the monkey SC. A distributed set of connections to horizontal and vertical motor burst generators is trained to allow the model to make accurate the scacades to randomly selected target positions. Finally, the model is able to produce accurate eye movements and realistic neural discharge for saccades evoked with a variety of experimental conditions which are not included in the training set (for example, averaging and express saccades).

Selected Publications

Arai, K, Keller, E.L., and Edelman, J.A., "Two-dimensional model of the primate saccadic system", Neural Networks 7:1115-1135

Keller, E.L. and Edelman, J.A., "Use of interrupted saccade paradigm to study spatial and temporal dynamics of saccadic burst cells in superior colliculus in monkey.