paper available

[Lina Massone]

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The following paper is available.

		A VELOCITY-BASED MODEL FOR CONTROL
			OF OCULAR SACCADES
		
			Lina L.E. Massone

	    	     Department of Physiology
     	   Department of Electrical Eng. and Comp. Sci.
	    	     Northwestern University


This paper presents a computational closed-loop model of the saccadic
system based on the experimental observation by Munoz, Pellisson and
Guitton [1991] that the neural activity on the collicular motor map
shifts, during eye movements, towards the rostral area of the superior
colliculus. This assumption, together with other assumptions on how
the colliculus projects to the burst cells in the brainstem and on the
architecture of the network that translates the collicular signal into
actual eye movements, results in a system that can: (1) perform a
spatio-temporal transformation between a stimulation site on the
collicular motor map and an eye movement, (2) spontaneously produce
oblique saccades whose trajectories are, as dictated by experimental
data, curved when the horizontal and vertical components of the motor
error are unequal and straight when the horizontal and vertical 
components of the motor error are equal, (3) automatically maintain
the eye position in the orbit at the end of a saccade by exploiting
the internal dynamic of the network, (4) continuously produce
efferent copies of the movements without the need for reset signals, 
(5) reproduce the outcome of the lidocaine experiment by Lee, Roher
and Sparks [1988] without assuming a population averaging criterion
to combine the activity of collicular cells. This model was developed 
as part of a theoretical study on the common properties of the eye
and arm control systems and on the hypothetical role that the tecto-
reticulo-spinal tract might play in the control of arm movements.

Munoz, Pellison, Guitton [1991] Movement of neural activity on the
superior colliculus motor map during gaze shifts, Science, 251, 
1358-1360.

Lee, Roher, Sparks [1988] Population coding of saccadic eye movements
by neurons in the superior colliculus, Nature, 332, 357-360.



A poster will be at NIPS.
Email requests to: lina at mimosa.physio.nwu.edu