Neurons in Dorsal Anterior Cingulate Cortex Signal Postdecisional Variables in a Foraging Task. Blanchard, Hayden. Journal of Neuroscience 2004.

  1. “The dorsal anterior cingulate cortex (dACC) is a key hub of the brain’s executive control system.” but the way it leads to decision making isn’t clear.  Theories are
    1. Predecisional: Tracks option values which lead to decision making
    2. Postdecisional: dACC patterns differ qualitatively depending on the choice made
  2. Work tries to shed light on what is actually happening, based on a simple foraging task
    1. Options present both reward amount as well as cost (in terms of a delay)
  3. We found that dACC neurons signal the foregone value of the rejected option, a postdecisional variable.  Neurons also signal the profitability (thatis, the relative value) ofthe offer, but even these signals are qualitatively different on accept and reject decisions, meaning that they are also postdecisional. These results suggest that dACC can be placed late in the decision process and also support models that give it a regulatory role in decision, rather than serving as a site of comparison.
  4. dACC sits at the “interface” between reward and motor systems, and is connected to monitoring and adjustment
  5. It [dACC] is sensitive to received rewards, errors, and to differences between expected and obtained rewards (…). These signals appear to summate to indicate the balance of evidence in favor of adjustments to action or the need for control.”
  6. dACC signals related to “…balance of evidence in favor of adjustments to action or the need for control.”
  7. On the other hand, there isn’t much evidence in terms of direct contribution of dACC to value representation and deliberation related to choice.
  8. Stance here is that dACC is not “… directly involved, and instead function as a monitor and controller of both the decisions we make and of their outcomes.  If so, we would expect that its responses around the time of the decision to signal variables related to the chosen option and to depend qualitatively on the choice that is made.
    1. The other option is that dACC passes on option values and something else conducts decision making
  9. In the experiment, monkeys are presented with an option – which they can accept or reject.  Presumably if the option is better than what is otherwise available they will accept the offer, and otherwise reject.
  10. In the diet selection task, the foregone benefit of accepting an offer is a linear function of its delay and does not depend on its reward size, whereas the foregone benefit of rejecting is a linear function of its reward size and does not depend on its delay.”
    1. <I don’t understand how this statement is true?  In the abstract it says food is presented of a particular reward size only after the indicated delay period passes.  Its going to make it difficult for me to grok the rest of the paper if I can’t make sense of this. I’ll pass for now.>

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