Perceptual Decision Making in Primates
Previous studies of the posterior parietal cortex (CPP) in perceptual decisions only tested its contribution to the motor aspects of the decision. However, Zhou and Freedman have tested the role of the PPC primate in the sensory and motor aspects of decisions. Inactivation of the intraparietal lateral zone strongly altered the sensory processing aspects of decision making, even more than the motor aspects. Neurons of the intraparietal side region targeted for inactivation were strongly correlated with the decision, test-by-test, of monkeys regarding stimuli in the receptor fields of neurons. Thus, the posterior parietal cortex is actually involved in decision making but plays a more sensory role than expected.
Science, this number p. 180
Posterior parietal cortex (CPP) activity correlates with the decisions of monkeys during visual discrimination and categorization tasks. However, recent work has asked whether the activity of the decision-related CPC plays a causal role in such decisions. This study focused on the contribution of PCP to the motor aspects of the decision (deciding where to move), but not to sensory evaluation (deciding what you are looking at). We used reversible inactivation to compare CPP contributions to the motor and sensory aspects of decisions. Inactivation affected both aspects of behavior, but preferably impaired decisions when visual stimuli, rather than targets of the motor response, were in the field of view inactivated. This demonstrates a causal role for CPP in decision-making, with a preferential involvement in the evaluation of sensory stimuli related to the task to be monitored in relation to motor planning.