| |
Abstract:
The Error-related Negativity (ERN) is a fronto-centrally
distributed component of the event-related brain potential (ERP)
elicited when human subjects make errors in a variety of
experimental tasks. The ERN is associated with the activity of a
flexible error processing system and appears to be generated in the
anterior cingulate cortex. Computational models suggest that the
mesencephalic dopamine system may mediate a particular kind of
reinforcement learning signal called a "temporal difference error."
We hypothesize that the ERN is a manifestation of a cortical
response to a temporal difference error carried to the frontal
midline by the mesencephalic dopamine system. We propose that while
a subject engages in an experimental task, the basal ganglia
continually monitor motor activity, external cues and feedback, and
make ongoing predictions about whether each trial will end in
success or failure. When a positive or neutral estimate of a
trial's outcome is revised in favor of a prediction of failure, a
negative error signal is referred via the dopaminergic projection
to frontal motor areas, where an ERN is generated. This hypothesis
is formalized in a computational model based on the method of
temporal differences. We discuss several predictions made by the
model that can be tested in a future event-related potential
experiment involving probabilistic learning.
|
