The top 4 panels show the distribution of brain-derived neurotrophic factor (BDNF) mRNA in (A) control, (B) schizophrenia, (C) bipolar disorder and (D) major depression groups. Middle panels display the distribution of tyrosine kinase receptor (trkB-TK+) mRNA in (E) control, (F) schizophrenia, (G) bipolar disorder and (H) major depression groups, and the bottom panels show the distribution of glutamic acid decarboxylase (GAD67) mRNA in (I) control, (J) schizophrenia, (K) bipolar disorder and (L) major depression groups.