Results of PET data analysis in different regions of interest. Top: [18F]MPPF-specific binding (ratios to cerebellum); pharmacological challenge with NLX-112 (a) or NLX-101 (b) at t = 50 min (arrow). Results are expressed in percentage compared to baseline between 40 and 50 min (n = 4, ±standard deviation). **p < 0.01; ***p < 0.001; ****p < 0.0001 (Bonferroni’s post hoc test compared to control condition). Down: 5-HT1A occupancy by NLX-101 and NLX-112 at increasing doses. Results are expressed in percentage of occupancy (n = 4). c Doses of 0.04 mg/kg; d Doses of 0.08 mg/kg; e Doses of 0.16 mg/kg. Cing Ctx cingulate cortex, Front Ctx frontal cortex, Occ Ctx occipital cortex, Par Ctx parietal cortex, Temp temporal cortex