RT Journal Article
SR Electronic
T1 Hierarchical Learning Induces Two Simultaneous, But Separable, Prediction Errors in Human Basal Ganglia
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 5797
OP 5805
DO 10.1523/JNEUROSCI.5445-12.2013
VO 33
IS 13
A1 Carlos Diuk
A1 Karin Tsai
A1 Jonathan Wallis
A1 Matthew Botvinick
A1 Yael Niv
YR 2013
UL http://www.jneurosci.org/content/33/13/5797.abstract
AB Studies suggest that dopaminergic neurons report a unitary, global reward prediction error signal. However, learning in complex real-life tasks, in particular tasks that show hierarchical structure, requires multiple prediction errors that may coincide in time. We used functional neuroimaging to measure prediction error signals in humans performing such a hierarchical task involving simultaneous, uncorrelated prediction errors. Analysis of signals in a priori anatomical regions of interest in the ventral striatum and the ventral tegmental area indeed evidenced two simultaneous, but separable, prediction error signals corresponding to the two levels of hierarchy in the task. This result suggests that suitably designed tasks may reveal a more intricate pattern of firing in dopaminergic neurons. Moreover, the need for downstream separation of these signals implies possible limitations on the number of different task levels that we can learn about simultaneously.