Angela L. Hewitt


     Year Entered: 2005

     Degrees Received:
     University of Wisconsin, Madison
     Biomedical Engineering major
     B.S., 2002
     M.S., 2005

     Honors and Awards:
NRSA Individual Predoctoral MD/PhD Fellowship (F30), NINDS, NIH,
     -Travel Award to 2009 "Combining Clinical and Research Careers in
     Neuroscience" conference in Washington, DC sponsored by the
     National Institute of Neurological Disorders and Stroke, Association of
     University Professors of Neurology, and the American Neurological
     -NIH Roadmap Computational Neuroscience Training Grant, 2007-2009
-Student Interest Group in Neurology (SIGN), president-elect 2006-2007, president 2007-2008
-Finalist, National Collegiate Inventors Competition, 2002
-University of Wisconsin Hilldale Undergraduate Research Fellowship, 2002
-4th place Schoof's Prize for Creativity Innovation Competition, 2002

Thesis Advisor: Timothy Ebner, M.D., Ph.D.

Thesis Research: 
Motor control theorists have postulated that production of rapid, coordinated movements requires control circuitry that can bypass sensory feedback delays by providing an estimate of the consequences resulting from a motor command.  This control element, termed a forward internal model, receives an efferent copy of the motor command and information about the current state in order to predict the future state of the limb (i.e, kinematic variables like position and velocity).  Previous pychophysical, imaging, and patient case studies suggest that the cerebellum is a possible location for implementation of an internal model.  However, few electrophysiological studies have investigated whether the firing discharge from cerebellar neurons is consistent with the properties of a forward internal model.  The ultimate goal of this project is to evaluate whether the simple spike firing from Purkinje cells (PCs) in lobules IV-VI of the intermediate/lateral cerebellar zones is consistent with output from a forward internal model.  Although no single result will conclusively prove this hypothesis, two electrophysiology experiments examining hand movements in rhesus macaques are proposed to test several aspects of a forward internal model.  Aim 1 will examine whether PC firing predicts future hand kinematics in a task-independent manner.  Aim 2 will further evaluate model adaptability and whether changing model inputs alters predicted kinematics.  The results will either show that PC firing is incompatible with the output expected from a forward model or provide solid support for future experiments.

Previous Research Experience:
Angela's  research emphasis prior to entering the University of Minnesota was neuromusculoskeletal movement.  Her research interests include brain control interfaces, sensory prosthetics, functional neural imaging, neural control of movement.  She participated in several academic design projects at the University of Wisconsin, one of which resulted in a patent and another with a patent pending:.

  • U.S. Patent No 6,702,765: Apparatus for Measuring Tongue/Hard Palate Contact Pressure.
    Inventors: Robbins, JoAnne; Bomsztyk, Elan D.; Heppner (Hewitt), Angela L.; Koranda, Christine L.; Kroner, Aaron R.; Kuchenreuther, Jon M.; Meister, David M.; Staerkel, Bryan S.
  • U.S. Patent No 7,238,145: Oral-lever Resistance Exercise Device  Inventors: Robbins, JoAnne; Hind, Jacqueline A; Hewitt, Angela L.

Publications (pubmed):

Hewitt AL, Popa LS, Pasalar S, Hendrix CM, Ebner TJ. Representation of limb kinematics in Purkinje cell simple spike discharge is conserved across multiple tasks. J Neurophysiol. 2011 Nov;106(5):2232-47.

Ebner TJ, Hewitt AL, Popa LS. What Features of Limb Movements are Encoded in the Discharge of Cerebellar Neurons? Cerebellum. 2011 Dec;10(4):683-93.

Hewitt A, Hind J, Kays S, Nicosia M, Doyle J, Tompkins W, Gangnon R, Robbins J. Standardized instrument for lingual pressure measurement. Dysphagia. 2008; 23(1): 16-25.

Robbins J, Kays SA, Gangnon RE, Hind JA, Hewitt AL, Gentry LR, Taylor AJ. The effects of lingual exercise in stroke patients with dysphagia. Arch Phys Med Rehabil. 2007;88:150-158.

Robbins J, Gangnon R, Theis S, Kays S, Hewitt AL, Hind J.  The effects of lingual exercise on swallowing in older adults. J Am Geriatr Soc. 2005;53:1483-1489.