Tuesday, July 25, 2006

Remembering past rewards - anterior cingulate cortex needed

Here is the abstract from an interesting paper in Nature Neuroscience by Kennerley et al.

"Learning the value of options in an uncertain environment is central to optimal decision making. The anterior cingulate cortex (ACC) has been implicated in using reinforcement information to control behavior. Here we demonstrate that the ACC's critical role in reinforcement-guided behavior is neither in detecting nor in correcting errors, but in guiding voluntary choices based on the history of actions and outcomes. ACC lesions did not impair the performance of monkeys (Macaca mulatta) immediately after errors, but made them unable to sustain rewarded responses in a reinforcement-guided choice task and to integrate risk and payoff in a dynamic foraging task. These data suggest that the ACC is essential for learning the value of actions."

Here is a graphic (credit: Ann Thomson, Nature Neuroscience) in an accompanying review of this work by Haydn and Platt.

Monkeys with lesions in the anterior cingulate cortex (ACC) correct errors but fail to maintain the new rewarded behavior. (a) Medial view of the right hemisphere in the macaque. Shading, location of the lesion in the ACC. (b) Behavioral responses of monkeys with ACC lesions in experiment 1. After one action—in this case, lift—was rewarded for 25 consecutive trials, the rewarded action was switched—in this case, to turn. Following an unrewarded lift response, lesioned monkeys switched to turning, but could not sustain this response on subsequent trials. Intact monkeys, however, had no difficulty with this task. Similar lesion-induced disruptions in behavioral performance were found in a reward probability matching task in a second experiment.

1 comment:

  1. What you describe probably has to do with the anterior cingulate cortex's contributory role in processing long term memory.

    In the course of my studying human neuroimaging findings relating to reward activations in the cingulate cortex, I have found that reward initially activates the caudal region of the perigenual anterior cingulate cortex. As reward delivery becomes more uncertain activation sites transition more caudally toward the midcingulate region. But as activations become more certain and actually become realized, the activation sites transition ventrally and terminate in the subgenual region. The anterior cingulate cortex is indeed a very interesting brain structure.