The relationship between the dopamine and glutamate pathways in the normal brain

Stimulatory glutamate projections from the cortex activate dopamine pathways in the substantia nigra pars compacta. Dopamine is the predominant neurotransmitter in the substantia nigra and there are both stimulatory and inhibitory dopamine projections from this structure to other parts of the brain. Dopamine is predominantly inhibitory on the striatum, which affects the transmission from the striatum to the cortex and can elevate the transmission of sensory information to the cortex. If transmission through the thalamus becomes excessive, confusion and psychosis, as seen in schizophrenia, can occur.  Excessive transmission through the thalamus may be caused by either an increase in dopaminergic or a decrease in glutamatergic activity; increased levels of dopamine and decreased levels of glutamate have been implicated in the pathogenesis of schizophrenia.

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References

Int Clin Psychopharmacol 1995;10(Suppl 3):21–28.