Since 1950
physician referral

Meet The Medical & Behavioral Health Team


Regina Gargus, M.D., FAAP

Director of the Siskin Center for Developmental Pediatrics

Dr. Regina Gargus is Medical Director of the Center for Developmental Behavioral Pediatrics and Chief of the Division of Developmental Behavioral Pediatrics at Children’s Hospital at Erlanger.  Prior to coming to Chattanooga Dr. Gargus served as Medical Director of the J.L. Dennis Developmental Center at the University of Arkansas for Medical Sciences in Little Rock. Dr. Gargus received her medical degree from the Medical College of Virginia-Virginia Commonwealth University, where she also completed her pediatric residency and a neonatology fellowship. After a decade and a half as a medical director of neonatal services in Virginia, she completed a three-year developmental behavioral pediatric fellowship at Brown University School of Medicine in Rhode Island. Dr. Gargus is board certified by the American Board of Pediatrics in general pediatrics, neonatal-perinatal medicine and developmental behavioral pediatrics. Her academic interests are in developmental behavioral conditions in children, autism spectrum disorders, oppositionality in toddlers, bullying behaviors and developmental surveillance of children who required NICU care.  


Emily Brandt, M.D. FAAP

Dr. Emily Brandt joined the pediatric center team in August 2013. She completed a three year fellowship in developmental and behavioral pediatrics at the University of Iowa Children’s Hospital Center for Disabilities and Development. She received her medical degree at the Loma Linda University School of Medicine and completed her pediatric residency at the Loma Linda University Children’s Hospital. Dr. Brandt is board certified by The American Board of Pediatrics in general pediatrics and is board certified in Developmental-Behavioral Pediatrics.


Michelle Cahill Kimball, MSN, APRN, CPNP-PC

Michelle is a certified pediatric nurse practitioner with more than a decade of experience. Prior to joining the Center in 2010 she worked for a general pediatric practice in Fort Oglethorpe. Michelle received her baccalaureate degree from The University of Tennessee at Chattanooga and her Master's degree from Emory University. She also has served as an educational consultant for school nurses in Walker County, Georgia.


Ryan Grimes, MSN, CPNP

Ryan is a certified Pediatric Nurse Practitioner.  She received her baccalaureate degree from UNC Charlotte in Sociology and Child and Family Development, her associate degree in Nursing from Cabarrus College of Health Sciences, and her Master’s degree in Nursing from Vanderbilt University.

Prior to joining Siskin Children’s Institute, Ryan worked for a general pediatric practice in the Washington, D.C. metro area. Ryan is a member of Sigma Theta Tau International Honor Society of Nursing and the National Association of Pediatric Nurse Practitioners.

As a Chattanooga native, Ryan is excited to be joining an organization that serves the community she loves.  She looks forward to “paying it forward” by providing exemplary care to the children and families of such a notable institution as Siskin Children's Institute.


Megan McCullah, PA-C

Megan is a certified Physician Assistant who received her baccalaureate degree from East Tennessee State University in Biology and Psychology.  From there she obtained her Master’s in Physician Assistant Studies degree from Alderson-Broaddus College in Phillipe, West Virginia.  Her last year of training was spent at Wheeling Hospital in Wheeling, WV where her passion for pediatrics began.  Megan has five plus years in both primary care pediatrics and family practice.  Megan is thrilled to join Siskin Children’s Institute and begin practicing with the outstanding medical team and caring for families and children with special needs. 


Brandon Rodgers, Ph.D.

A Chattanooga native, Dr. Rodgers received his Ph.D. in human development with a specialty in marriage and family therapy from Virginia Tech. He is a licensed marital and family therapist by the Tennessee State Board of Professional Counselors, Marital and Family Therapists and Clinical Pastoral Therapists. In addition to being a certified psychological assistant by the Tennessee State Board of Examiners in Psychology, he is a nationally certified school psychologist. He has presented at numerous conferences and workshops around the country, including the American Association for Marriage and Family Therapy (AAMFT) Annual Conference. Dr. Rodgers currently provides a range of individual, family, and group behavioral health services at the Center for Developmental Pediatrics. He has previously taught courses at Virginia Tech, Appalachian State University, and Western Carolina University and is currently a Clinical Assistant Professor at the University of Tennessee - College of Medicine.


Margaret (Peggy) Wilkins, Ph.D.

With 20 years of clinical experience, Dr. Wilkins is a licensed clinical psychologist (HSP) by the Tennessee State Board of Examiners in Psychology. Dr. Wilkins received her Ph.D. in clinical psychology from Auburn University and is a clinical member of the American Psychological Association (APA). She currently supervises the psychological assessment services provided at the Center for Developmental Pediatrics.