Inclusion Criteria: Subjects must meet all of the following inclusion criteria to qualify for enrollment into the study:
- 18 - 70 years of age;
- DSM-5 primary diagnosis of Bipolar Disorder type 1 (with a documented past manic episode), currently in a Major Depressive Episode by diagnostic criteria elicited by structured clinical interview (SCID-5-RV);
- MADRS score ≥ 20;
- Duration of current episode >4 weeks
- YMRS score ≤ 12;
- baseline EEG of sufficient quality for quantitative analysis processing;
- willing and able to adhere to the intensive treatment schedule and all required study visits;
- currently on adequate dose of mood stabilizer with significant evidence base or FDA approval as antimanic or for maintenance therapy of bipolar disorder (e.g, valproic acid/divalproex, carbamazepine, lithium, aripiprazole, ziprasidone, risperidone, quetiapine, olanzapine, asenapine, haloperidol, chlorpromazine, paliperidone, cariprazine).
Exclusion Criteria: Subjects will be excluded from study participation if one of the following exclusion criteria applies:
- unable or unwilling to give informed consent;
- diagnosed with current primary psychotic disorder (rather than BD);
- diagnosed with current mania or hypomanic mood episode;
- history of moderate to severe substance use disorder within the past 6 months (except nicotine and caffeine);
- currently being treated with a stimulant;
- clinically defined major neurological disorder; including, but not limited to, seizure disorder and history of loss of consciousness due to head injury for greater than 10 minutes, or with documented evidence of brain injury;
- increased risk of seizure for any reason, including diagnosis of increased intracranial pressure, comorbid neurological disorder, use of certain medications, highly unstable use of alcohol or benzodiazepines;
- initiation of new antidepressant treatments (new medication, new device-based stimulation, or new psychotherapy) within 6 weeks prior to study baseline;
- active suicidal intent or plan as detected on screening assessments, or in the Investigator's opinion, is likely to attempt suicide within the next six months;
- presence of implanted cardiac pacemakers, implanted medication pumps, or intracardiac lines;
- intracranial implant (e.g., aneurysm clips, shunts, stimulators, cochlear implants, stents, or electrodes) or any other metal object within or near the head (excluding the mouth), which cannot be safely removed;
- clinically significant unstable medical condition;
- if female: pregnant, not using medically acceptable means of birth control, or currently breastfeeding;
- other condition, which in the judgment of the Investigator could prevent the subject from completion of the study;
- for participants in the MRI study: ferromagnetic metal implant or other contraindication to imaging in a 3 Tesla MRI;
- past treatment with TMS therapy.