a | In schizophrenia, hypermetabolism in the anterior hippocampus occurs early in the disease process, and through monosynaptic connections this can be linked to orbitofrontal hypermetabolism that emerges later in the disease course. In animal models, hyperactivity in the anterior hippocampus stimulates the nucleus accumbens, leading to increased striatal dopamine release. b | Studies in patients with depression suggest that hypermetabolism in the anterior hippocampus occurs early in the disease process, and via monosynaptic connections this may be linked to hypermetabolism observed in the amygdala and the anterior cingulate.