Inclusion Criteria (primary premature ejaculation subjects):

• patients' age varied from 18 to 45 years；
• patients met the 2014 International Society for Sexual Medicine (ISSM) definition criteria for PPE；
• patients had a stable, heterosexual relationship with a single sexually active female partner for at least 6 months and with at least two sexual intercourses a week and kept stable during the study period;
• Patients with premature ejaculation lasting longer than 6 months；
• patients were identified if their scores were higher than 9 on the Chinese version of Premature Ejaculation Diagnostic Tool (PEDT);
• patients had no history of any previous therapies for PE or had recently stopped the therapies for at least 3 months
• patients had fully informed consent, signed informed consent form

Inclusion Criteria (Non-premature ejaculation subjects):

• Men between the ages of 18-45 years were included according to an age difference of <3 years between each patient and the primary premature ejaculation group, and if more than one volunteer was eligible at the same time, the one with the closest age was selected；
• Patient does not meet the 2014 International Society for Sexual Medicine (ISSM) criteria for defining premature ejaculation；
• patients had a stable, heterosexual relationship with a single sexually active female partner for at least 6 months and with at least two sexual intercourses a week and kept stable during the study period;
• patients had fully informed consent, signed informed consent form；

Exclusion Criteria:

• patients were diagnosed with secondary PE, variable PE, and subjective PE;
• patients were using medications for endocrinological, metabolic, chronic systemic, or psychiatric diseases;
• patients were abusing alcohol or illegal drugs；
• patients were diagnosed with erectile dysfunction (ED) if their scores were <21 on the abridged five-item International Index of Erectile Function (IIEF-5)
• patients were diagnosed with sexual hormone abnormalities, hyperthyroidism, hypothyroidism, Peyronie's disease, prostatitis, urethritis, or urinary tract infection;
• patients with head injuries that prevent them from completing near-infrared light brain function imaging
• Patients with severe schizophrenia, anxiety, depression or other neurological symptoms or poor compliance