Robust and distributed neural representation of action values

Studies in rats, monkeys, and humans have found action-value signals in
multiple regions of the brain. These findings suggest that action-value
signals encoded in these brain structures bias choices toward higher
expected rewards. However, previous estimates of action-value signals
might have been inflated by serial correlations in neural activity and
also by activity related to other decision variables. Here, we applied
several statistical tests based on permutation and surrogate data to
analyze neural activity recorded from the striatum, frontal cortex, and
hippocampus. The results show that previously identified action-value
signals in these brain areas cannot be entirely accounted for by parallel
serial correlations in neural activity and action value. We also found
that neural activity related to action value is intermixed with signals
related to other decision variables. Our findings provide strong evidence
for broadly distributed neural signals related to action value throughout
the brain.