Inclusion Criteria:  Patients;  Aged between 18 and 65 Having a diagnosis of bipolar type I disorder depressive episode by Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) Having no other general medical, neurological or psychiatric condition Healthy controls; Matched with bipolar depressive patients by age and sex Having no other general medical, neurological and psychiatric condition  Exclusion Criteria:  Bipolar depressive patients and healthy control subjects with any other general medical, neurological or psychiatric condition, metal implant, severe head injury or pregnancy