Midbrain dopamine (DA) neurons are not homogeneous
but differ in their molecular properties and
responses to external stimuli. We examined whether
the modulation of excitatory synapses onDAneurons
by rewarding or aversive stimuli depends on the brain
area to which these DA neurons project.Weidentified
DA neuron subpopulations in slices after injection of
‘‘Retrobeads’’ into single target areas of adult mice
and found differences in basal synaptic properties.
Administration of cocaine selectively modified excitatory
synapses on DA cells projecting to nucleus
accumbens (NAc)medial shell while an aversive stimulus
selectively modified synapses on DA cells
projecting to medial prefrontal cortex.