HTR2A and supranuclear palsy, progressive, 1: In contrast to this, significantly higher N-methyl-d-aspartate (NMDA), γ-aminobutyric acid receptor type B (GABAB), pBZ, and serotonin receptor type 2 (5-HT2) receptor densities were found in area 24′ of PSP patient brains than in control brains (Table 5, Fig. 1d).