80 male and female subjects will be recruited: 20 with IBS D; 20 with IBS C; 20 with IBS M; 20 control (no bowel symptoms). We will target patients who have maintained a diagnosis of IBS with Diarrhea (IBS-D), IBS with Constipation (IBS-C, IBS with Mixed Stool pattern (IBS-M), using Rome III Criteria as well as control subjects without bowel symptoms. Subject participation will be limited to patients who maintain mild or moderate symptom severity score on the functional bowel disorders severity index (FBDSI.) providing they have at least 3 symptom episodes of pain or discomfort in a given week, to assure adequate data collection.

Inclusion Criteria:

1. The subject signs and dates a written informed consent form (ICF) prior to any study-related activities, including discontinuation of any prohibited medications.
2. The subject has been diagnosed with either IBS-C, IBS-D, IBS-M, or has no history of gastrointestinal symptoms (control group).
3. The subject has at least 3 pain episodes a week and does not have constant, unremitting abdominal pain.
4. The subject is at least 18 years of age and less than 75 years of age at the time of the screening visit.
5. The subject is fluent in English.
6. The subject is an ambulatory outpatient. Ambulatory is defined as not depending exclusively on a wheelchair for mobility. Nursing home subjects may be enrolled provided they are ambulatory. Subjects with spinal cord injuries resulting in paraplegia may not be enrolled.

Exclusion Criteria:

1. The subject exhibits evidence of a biochemical or structural abnormality of the digestive tract. These conditions include (but are not limited to) the following:

   • Inflammatory bowel disease (Crohn's disease or ulcerative colitis),
   • GI surgery (with the exceptions of appendectomy; cholecystectomy; benign polypectomy; fundoplication without gas bloat syndrome, 6 months post-surgery; herniorrhaphy without bowel resection, 1 month post-surgery; hemorrhoidectomy, at least 2 months post-surgery; and hiatal hernia repair),
   • GI malignancy, GI obstruction
2. In the opinion of the investigator the subject has a concurrent illness or disability (excluding IBS) that may affect the interpretation of clinical efficacy and/or safety data or otherwise contraindicates participation in this clinical study (e.g., an unstable cardiovascular, renal, hepatic, pulmonary, endocrine, metabolic, GI, hematological, or neurological condition).
3. The subject has been diagnosed with a major psychiatric disorder within the past 2 years that required hospitalization and/or involved an attempted suicide (e.g., major depression or psychoses). Subjects diagnosed with a major psychiatric disorder that did not require hospitalization or involve an attempted suicide must have remained on a stable dose of medication for at least 6 months prior to the screening visit.
4. The subject has a history of alcohol or substance abuse within the past 2 years.
5. The subject has any evidence or treatment of malignancy (other than localized basal cell, squamous cell skin cancer or cancer in situ that has been resected) within the previous 5 years.