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Behavioral/Systems/Cognitive Target Selection Signals for Arm Reaching in the Posterior
 

Summary: Behavioral/Systems/Cognitive
Target Selection Signals for Arm Reaching in the Posterior
Parietal Cortex
Hansjo¨rg Scherberger and Richard A. Andersen
Division of Biology, California Institute of Technology, Pasadena, California 91125
Theselectionofvisualstimuliasatargetforamotoractionmaydependonexternalaswellasinternalvariables.Theparietalreachregion
(PRR)intheposteriorparietalcortexplaysanimportantroleinthetransformationofvisualinformationintoreachmovementplans.We
asked how neurons in PRR of macaque monkeys reflect the decision process of selecting one of two visual stimuli as a target for a reach
movement. Spiking activity was recorded while the animal performed a free-choice task with one target presented in the preferred
direction and the other in the off direction of the cell. Stimulus-onset asynchrony (SOA) was adjusted to ensure that both targets were
selected equally often and the amount of reward was fixed. Neural activity in PRR was action specific for arm reaching and reflected the
timingoftheSOAaswellastheselectionofreachtargets.Inindividualtrials,activitywasstronglylinkedtothechoiceoftheanimal,and,
forthemajorityofcells,targetselectionscouldbepredictedfromactivityinthestimulationorplanningperiod,i.e.,beforethemovement
started. Many neurons were gain modulated by the fixation position, but gain modulation did not influence the target selection process
directly. Finally, it was found that target selection for saccade movements was only weakly represented in PRR. These findings suggest
that PRR is involved in decision making for reach movements and that separate cortical networks exist for target selection of different
types of action.
Key words: sensorimotor transformation; motor system; movement planning; decision making; monkey; parietal reach region
Introduction
The posterior parietal cortex (PPC) plays a crucial role for the

  

Source: Andersen, Richard - Division of Biology, California Institute of Technology
Scherberger, Hansjörg - German Primate Center & Georg-August-Universität Göttingen

 

Collections: Biology and Medicine; Computer Technologies and Information Sciences; Physics