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

Senior Clinician

Motor Neuron Disorders Unit


Building 10-CRC, Room 1D45
10 Center Drive, MSC 1404
Bethesda, MD 20892-1404


Research Topics

The NINDS Motor Neuron Disorders Unit studies neurodegenerative disorders that affect corticospinal and spinal motor neurons that control voluntary movement. Primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) are examples of rare disorders in which neurons responsible for voluntary movements undergo degeneration. Corticospinal (upper) motor neurons degenerate in both disorders; spinal (lower) motor neurons also degenerate in ALS, but are relatively spared in PLS. We are interested in understanding how these disorders are related and finding biomarkers of disease progression or prognosis. We hypothesize that functional changes will precede structural changes, with a sequence reflecting cell death, inflammation, axonal breakdown and tissue remodeling. Multimodal imaging and physiology studies are being used to explore these questions. 

ALS, PLS, and frontotemporal dementia (FTD) have been proposed to form a spectrum of neurodegenerative disease because of overlapping clinical symptoms and pathological features. In 2011, a hexanucleotide repeat expansion in the gene C9ORF72 was found to cause ALS and FTD, extending the evidence for this proposal to  genetics. To better understand the range of clinical presentations of this mutation in C9ORF72 and how clinical symptoms progress, we are carrying out a prospective longitudinal study of C9ORF72-related disorders, with imaging, physiological, and biofluid studies. This study of C9ORF72-related disease is highly collaborative, with investigators in laboratories at NINDS, NIA, and outside institutions, including agreements for sharing biospecimens.


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 in physiology at UCSF, she came to NIH as a senior staff fellow in the Laboratory of Neural Control to study the physiology of motor neurons and mammalian spinal cord circuits controlling movement. She joined the EMG section as a clinical associate in Clinical Neurophysiology three years later and served as Chief of the NINDS EMG Section 1996-2014. She was appointed as the NINDS Deputy Clinical Director in 2006, and became a Senior Clinician in 2008. Dr. Floeter’s current research focuses on two rare motor neuron disorders: primary lateral sclerosis and C9ORF72-associated amyotrophic lateral sclerosis and frontotemporal dementia.

Selected Publications

  1. Floeter MK, Danielian LE, Braun LE, Wu T. Longitudinal diffusion imaging across the <i>C9orf72</i> clinical spectrum. J Neurol Neurosurg Psychiatry. 2018;89(1):53-60.

  2. Floeter MK, Bageac D, Danielian LE, Braun LE, Traynor BJ, Kwan JY. Longitudinal imaging in <i>C9orf72</i> mutation carriers: Relationship to phenotype. Neuroimage Clin. 2016;12:1035-1043.

  3. Floeter MK, Traynor BJ, Farren J, Braun LE, Tierney M, Wiggs EA, Wu T. Disease progression in <i>C9orf72</i> mutation carriers. Neurology. 2017;89(3):234-241.

  4. Cardenas AM, Sarlls JE, Kwan JY, Bageac D, Gala ZS, Danielian LE, Ray-Chaudhury A, Wang HW, Miller KL, Foxley S, Jbabdi S, Welsh RC, Floeter MK. Pathology of callosal damage in ALS: An <i>ex-vivo</i>, 7 T diffusion tensor MRI study. Neuroimage Clin. 2017;15:200-208.

  5. Iwata NK, Kwan JY, Danielian LE, Butman JA, Tovar-Moll F, Bayat E, Floeter MK. White matter alterations differ in primary lateral sclerosis and amyotrophic lateral sclerosis. Brain. 2011;134(Pt 9):2642-55.

This page was last updated on September 1st, 2018