Quantification of (A) full-length (FL)/truncated and (B) truncated/full-length (FL) TrkB isoform protein ratios in fusiform gyrus of autism and control samples. **p = 0.002 and **p = 0.009, respectively, 2-tailed t tests. Bars indicate mean ± SE. Autism, n = 11; control, n = 13. (C) Quantification of full-length (FL) TrkB and (E) truncated TrkB isoform protein expression in fusiform gyrus of autism and control samples by Western blotting. Each sample was normalized to its β-actin. **p = 0.003 for TrkB-FL and p = 0.09 for truncated TrkB isoforms, 2-tailed t tests. Bars indicate mean ± SE. Autism, n = 11; control, n = 13. The mean from two independent Western blots per sample was used for statistical analysis. (D) and (F) Representative Western blots of fusiform gyrus showing autism (A) and control (C) cases. Lanes 2 to 5: standard curve consisting of different amounts of total protein from a single normal human cortex sample. Lanes 6 to 13: 35 μg of total protein from each autism and control sample.