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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:32 |
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Conference: Bucharest University Faculty of Physics 2001 Meeting
Section: Biophysics; Medical Physics
Title:
Predictive Coding of Motion in Macaque Frontal Eye Fields
Authors:
Andrei Barborica*, Vincent P. Ferrera**
Affiliation:
Center for Neurobiology and Behavior, Columbia University, 722 W 168th St PI Annex Rm 729, New York, NY 10032
E-mail
Keywords:
Abstract:
Taking predictive actions in the continuously changing dynamic environment is a general feature of our daily experience. Object may move faster than the response time of the sensorimotor pathways, or objects in motion may even be temporarily occluded by other objects, in either case predictive action being required. The goal of our studies is to understand the neural mechanisms underlying cognitive predictions for movement control in the frontal eye fields (FEF) of primates. While previous studies focused mainly on the behavior of primates during target motion prediction, we are adding neural recordings in FEF of macaque monkeys to the existing data. In our paradigm a target is moving at constant speed and direction and it becomes invisible for a certain time, as being occluded by an object. We are comparing the results for these trials with the ones for two other sets of trials with the same motion properties (angle, speed) in which the target is either fully visible throughout its trajectory or invisible during the fixation period (the monkey has no clue on where or when the target is going to appear). The three different types of trials allow us to discriminate between the activity encoding the target expectancy, and the motor planning. In order to have further evidence that the monkey has a full representation of an invisible target, we designed a second paradigm, in which a deflector was inserted on the target path, during its occlusion period. The imaginary target hits the deflector and is deviated, the monkey having to calculate the changes in target direction and make a saccade to the location where it is supposed to reappear. The saccades landing position proved to be correlated with the predicted target location, based on the initial motion of the target and the angle of the deflector. Also, the magnitude of the responses during the occlusion interval proved to be correlated with the responses during the delay interval of a standard spatial memory task, suggesting that working memory may be actively involved in the predictive process. The results of our experiments suggest that monkeys are capable of maintaining a representation of moving invisible targets and that the activity of PFC neurons is directly correlated with target features.
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