PVALB and schizophrenia: The fornix–hippocampus circuit1 is part of the classic Papez circuit,2 which has a crucial role in spatial memory, memory retrieval and verbal memory,3, 4 functions that are affected in schizophrenia.5 Studies investigating the hippocampus in schizophrenia highlighted volume loss,6, 7, 8, 9 altered diffusion properties10, 11, 12 and hypermetabolism13, 14 at the neuroimaging level and decrease in parvalbumin-immunoreactive γ-aminobutyric acid interneurons at the microscopic level.14, 15, 16