Human Spinal Physiology Unit - Division of Intramural Research

Mary Kay Floeter, M.D., Ph.D., Senior Clinician

Dr. Floeter received her MD and PhD at Washington University in St. Louis and completed residency training in Neurology at the University of California, San Francisco. After postdoctoral work at UCSF, she came to NIH as a senior staff fellow in the Laboratory of Neural Control to study mammalian spinal cord circuits controlling movement. She joined the EMG section as a clinical associate in Clinical Neurophysiology three years later and has served as Chief of the NINDS EMG Section since 1996 and as the NINDS Deputy Clinical Director since 2006. Dr. Floeter’s recent research is directed toward analyzing changes in motor neurons and spinal circuits in patients with disorders that disrupt the corticospinal motor system.

Laboratory Staff

Laura Danielian, M.S., Biomedical Engineer
Justin Y Kwan, M.D., Special Volunteer
Avner Meoded, M.D., Research Fellow
Olivia Schanz, B.S., Postbaccalaureate IRTA
Matt Stephen, B.S., Post baccalaureate Fellow

Research Interests

The human spasticity and spinal physiology unit studies neurological disorders affecting descending motor systems and spinal cord neurons controlling movements. One goal is to understand how the chronic loss of corticospinal input affects the properties of motor neurons and spinal interneurons to produce spasticity. Most of the current research focuses on patients with Primary lateral sclerosis (PLS) and related disorders. PLS is a particularly informative neurological disorder for exploring the role of the corticospinal system in movement; it is a rare, sporadic disorder of progressive spasticity that appears to be caused by selective degeneration of the corticospinal neurons or their axons. However, the etiology of PLS, and its relationship to amyotrophic lateral sclerosis (ALS) and other motor neuron disorders is uncertain. Another goal of our research is to understand the relationship between PLS and ALS. Clinical, physiological, imaging, and pathological studies are used to better understand whether PLS and ALS represent different manifestations of a common disorder, and to guide research into the etiology of PLS.

Recent studies have focused on quantitative imaging biomarkers that may distinguish between PLS and ALS or correspond to clinical measures of progression. In diffusion tensor imaging studies we found that the pattern of white matter disruption in the corticospinal tract differed between ALS and PLS patients and from healthy age-matched controls. A consistent finding was that fractional anisotropy in the motor fibers of the corpus callosum was reduced in both PLS and ALS patients. Longitudinal studies, focusing on earlier stages of disease, are underway to discern how structural and functional changes in the voluntary motor system evolve in these disorders. Our goal is to find reliable imaging markers or physiological measures that are candidates for earlier detection of upper motor neuron dysfunction.

Clinical Protocols

Screening: Primary Lateral Sclerosis and related disorders 01-N-0145
Oxidative Stress in motor neuron disease 10-N-0121
Structural and Function Brain Imaging Markers of Upper Motor Neuron Function 12-N-0060

Selected Recent Publications

Kwan JY, Jeong SY, Van Gelderen P,Deng H-X, Quezado MM, Danielian LE, Butman JA,Chen L, Bayat E, Russell J, Siddique T, Duyn JH, Rouault TA, Floeter MK
Iron Accumulation in Deep Cortical Layers Accounts for MRI Signal Abnormalities in ALS: Correlating 7 Tesla MRI and Pathology, PLoSOne, 2012, vol. 7(4), pp. e35241. Full Text/Abstract
Iwata NK, Kwan JY, Danielian LE, Butman J, Tovar Moll F, Bayat E, Floeter MK
White matter alterations differ in primary lateral sclerosis and amyotrophic lateral sclerosis, Brain, 2011, vol. 134, pp. 2642-2655. Full Text/Abstract
Danielian LE, Iwata NK, Thomasson DM, Floeter MK
Reliability of longitudinal fiber tracking measurements in diffusion tensor imaging, Neuroimage, 2010, vol. 49, pp. 1572-1580. Full Text/Abstract
Bai O, Lin P, Huang D, Fei DY, Floeter MK
Towards a user-friendly brain-computer interface: Initial tests in ALS and PLS patients, Clin Neurophysiol, 2010, vol. 121, pp. 1293-303. Full Text/Abstract
Huey ED, Koppel J, Armstrong N, Grafman J, Floeter MK
A pilot study of the prevalence of psychiatric disorders in PLS and ALS, Amyotroph Lateral Scler, 2010, vol. 11, pp. 293-7.
Floeter MK and Mills R
Progression in primary lateral sclerosis: a prospective study, Amyotrophic Lateral Sclerosis, 2009, vol. 10, pp. 339-346.
Bai O, Lin P, Vorbach S, Floeter MK, Hattori N, Hallett M.
A high performance sensorimotor beta rhythm-based brain-computer interface associated with human natural motor behavior., J Neural Eng., 2008, vol. 5(1), pp. 24-35.
Bai O, Vorbach S, Hallett M, Floeter MK.
Movement-related cortical potentials in primary lateral sclerosis, Ann Neurol, 2006, vol. 59, pp. 682-690.

Selected Earlier Publications

Contact Information

Human Spinal Physiology Unit
Medical Neurology Branch, NINDS
Building 10-CRC, Room 7-5680
10 Center Drive, MSC 1404
Bethesda, MD 20892-1404

Telephone: 301-496-7428 (office), 301-496-7428 (laboratory), 301-402-8796 (fax)
Email: FloeterM@ninds.nih.gov