  The Basal Ganglia is a central structure involved in multiple cortical and
subcortical loops. Some of these loops are believed to be responsible for
saccade target selection. We study here how the very specific structural
relationships of these saccadic loops can affect the ability of learning
spatial and feature-based tasks.
  We propose a model of saccade generation with reinforcement learning
capabilities based on our previous basal ganglia and superior colliculus
models. It is structured around the interactions of two parallel cortico-basal
loops and one tecto-basal loop. The two cortical loops separately deal with
spatial and non-spatial information to select targets in a concurrent way. The
subcortical loop is used to make the final target selection leading to the
production of the saccade. These different loops may work in concert or disturb
each other regarding reward maximization. Interactions between these loops and
their learning capabilities are tested on different saccade tasks.
  The results show the ability of this model to correctly learn basic target
selection based on different criteria (spatial or not). Moreover the model
reproduces and explains training dependent express saccades toward targets
based on a spatial criterion.
  Finally, the model predicts that in absence of prefrontal control, the
spatial loop should dominate.
