Which of the following statements is true regarding action selection?
a. The direct pathway of the striatum encodes benefit and is mediated by D1 receptors, which are excitatory.
b. The indirect pathway of the striatum encodes costs and is mediated by D2 receptors, which are inhibitory.
c. Action selection and movement initiation in Parkinson's disease are enhanced because the dopaminergic neurons of the substantia nigra compacta (SNc) become overexcitable.
d. The basal ganglia and dopaminergic systems play important roles in action selection, such as for voluntary movements.
e. a, b, & d
