Brain Changes in Psoriasis After Secukinumab Treatment

Inclusion: 1. Between 18 and 65 years of age. 2. Psoriasis patients (with/without psoriatic arthritis): Psoriasis Area (BSA) is more than 5%. 3. Psoriasis patients must have had a TB test in the past 8 months (if a patient has not had one, the study will provide one). 4. Healthy subjects: in general, good health without history of neurological and psychiatric diseases. No chronic itch, pain, skin or systemic conditions currently or in the past. 5. Women of child bearing potential will be administered a pregnancy test to verify that they are not pregnant. 6. MRI Compatibility: No major contraindication for MRI (pacemaker, vascular stents, metallic ear tubes, and absence of metal implants or braces) as assessed by MRI technologist using site approved screening form. 7. Participants have to be able to speak and read English fluently. 8. Participants must have signed a written informed consent before being enrolled in the study Exclusion: 1. Individuals under 18 or over 65 years of age. 2. Inability to complete the required measures. 3. Participants who use antihistamine drugs for itch relief 4. Suffering from any disease state or physical condition, which would increase their health risk by study participation. 5. Patients with chronic infectious diseases (e.g., mycobacterial and fungal infections and chronic tuberculosis) or inflammatory bowel disease. 6. Patients without a negative TB test in the past 12 months. 7. Hypersensitivity or anaphylaxis to biologics 8. Patients with treatment of biologics should not receive live vaccines. Thus, age appropriate immunizations according to current immunization guidelines must be completed before the experiment. 9. Patients with primary immunodeficient lacking IL-17, patients with autoantibodies against IL-17 10. Currently enrolled in any investigational study in which the subject is receiving any type of drug, biological, or non-drug therapy. 11. Recent initiation (within last 3 months) or change in dose of centrally acting agents such as antidepressants, neuroleptics or neuropathic medications. 12. Patients who were previously treated with drugs targeting IL-17 13. Patients who have used biologics in the past in the past 8 weeks or Otezla in the past 4 weeks. 14. Patients who use centrally acting agents only when they need. The purpose is to avoid a risk of acute effect of these agents on brain activity. 15. Current treatment with opioid analgesics. 16. Uncontrolled thyroid disease. 17. Use of illicit drugs or history of opiate addiction. 18. Diagnosis of a major psychiatric disorder such as schizophrenia, major depression or bipolar disorder that is active currently. 19. Morbid obesity 20. Weight: 250 lb or more 21. Any known diseases or disorders that may affect conducting the experiments (e.g., intracranial pathology, claustrophobia, severe respiratory or cardiovascular problems, active fibromyalgia) or diseases that have potential risks of infections (e.g., HIV, Hepatitis C, etc). 22. Inability to speak and read English. 23. Pregnant. 24. Incarcerated.