Types of pathways The<unk>  (and striatum in general) has numerous, parallel circuits that allow for cortico-subcortico-cortico communication loops. These have been described, broadly, as the direct, indirect, and hyper direct pathways. GABAergic projections of the<unk>  have an inhibitory effect on the thalamus. Thalamic projections from the centromedian and parafascicular nuclei have an excitatory effect on the<unk> . Unlike the thalamus, which has broad reciprocal connectivity, cortical projections with the<unk>  are afferent, thus sending information as opposed to receiving it. Cortical communication is accomplished via multi-fiber pathways as outlined previously (i.e. via other subcortical structures). Dopamine Dopamine is a neurotransmitter that has a dominant role in the<unk> , most of it is supplied from the substantia nigra. When a cell body of a neuron (in the<unk>  or caudate nuclei) fires an action potential, dopamine is released from the presynaptic terminal. Since projections from the<unk>  and caudate nuclei modulate the dendrites of the substantia nigra, the dopamine influences the substantia nigra, which affects motor planning. This same mechanism is involved in drug addiction. In order to control the amount of dopamine in the synaptic cleft, and the amount of dopamine binding to post synaptic terminals, presynaptic dopaminergic neurons function to reuptake the excess dopamine. Other neurotransmitters The<unk>  also plays a role in modulation of other neurotransmitters. It releases GABA, enkephalin, substance P, and acetylcholine. It receives serotonin and glutamate.
Putamen
Inferior colliculus
Arcuate nucleus 
Periventricular nucleus
Barrel cortex
Medulla
Medulla 
Piriform cortex