Stability of Motor Output in Aging Adults

Corticobulbar Motor Output in Aging Adults

The goal of this project is to examine the area of the brain that controls muscle movement for a group of muscles important for swallowing, and to see how that area changes over 2 weeks of time.

Study Overview

• Status: Completed
• Conditions: Swallowing

Detailed Description

A large number of our nation's veterans develop dysphagia due to the myriad of potential etiological sources of swallowing disorders, including stroke and head and neck cancer. The Veteran's Health Administration has recently identified dysphagia as a major clinical focus for the VA system (Sullivan & Dennis, 2006). In order to accurately assess adaptations in motor cortex, it is first necessary to have a reliable tool for measuring organizational representation in the motor cortex. Transcranial magnetic stimulation (TMS) is a desirable choice for such measurement because of the ability to identify causative relationships between an area of motor cortex stimulated and muscle response. Therefore, the specific research objectives of this proposal are:

1. To demonstrate the reproducibility of TMS mapping of the submental muscle group in healthy older adults between 60 and 80 years of age
2. To determine the neural representation of submental musculature in the motor cortex of healthy older adults between 60 and 80 years of age.

Twenty healthy adults, 10 men and 10 women, between the ages of 60 and 80 years will serve as research participants. TMS will be used to establish motor maps of the submental muscles. Subjects will undergo two testing sessions, on day 1 and day 14. The results from each session will be compared to assess excitability and representation within the motor cortex, and to assess stability and reliability of measurement.

• Study Type: Observational
• Enrollment (Actual): 20

Contacts and Locations

Study Locations

• United States
  • Florida
    • Gainesville, Florida, United States, 32608
      • North Florida/South Georgia Veterans Health System

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Healthy adults between 60 and 80 years of age

Description

Inclusion Criteria:

• Between 60 and 80 years of age

Exclusion Criteria:

• History of dysphagia
• History of neurologic disease
• History of head or neck cancer
• History of stroke
• Untreated hypertension
• History of a heart condition or heart disease
• Currently pregnant

• Contraindication to TMS including:

  • Metallic hardware on the scalp in the area where TMS will be applied
  • Cardiac pacemaker
  • Implanted medication pumps or an intracardiac line
  • Prior diagnosis of seizure or epilepsy in the subject (childhood history of benign febrile seizure will not be a contraindication)
  • Poorly controlled migraine headaches
  • Previous brain neurosurgery
  • Medications that can lower seizure threshold (Appendix B)
  • Unstable medical conditions
  • Lowest motor thresholds above 80% on TMS

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
1; 20 healthy participants between 60 and 80 years of age. Ten men and 10 women.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Motor Evoked Potential Amplitude for Submental Cortical Representation	Cortical sites are stimulated sequentially from the SOLMT in the anterior direction. At each site, 5 pulses of 110% of the MEP threshold obtained at the SOLMT are delivered and recorded. If a site produces no MEP in 3/5 pulses it is considered non-submental. This process is continued until the entire submental representation is surrounded by non-submental responsive sites. The number of sites is used to calculate the area of submental representation. The mean sEMG amplitudes of the submental muscles for each of these sites is then calculated for the mean MEP measure.	2 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Motor Map Center of Gravity	Position on the TMS motor map with highest amplitude response to stimulation in the muscles of interest (submental muscles).	2 weeks
Area of Submental Representation	Cortical sites are stimulated sequentially from the SOLMT in the anterior direction. At each site, 5 pulses of 110% of the MEP threshold obtained at the SOLMT are delivered and recorded. If a site produces no MEP in 3/5 pulses it is considered non-submental. This process is continued until the entire submental representation is surrounded by non-submental responsive sites. The number of sites is used to calculate the area of submental representation.	2 weeks

Collaborators and Investigators

• Sponsor: US Department of Veterans Affairs
• Investigators: Principal Investigator: Karen Hegland, PhD, North Florida/South Georgia Veterans Health System

Study record dates

Study Major Dates

• Study Start: November 1, 2009
• Primary Completion (Actual): October 1, 2011
• Study Completion (Actual): October 1, 2011

Study Registration Dates

• First Submitted: September 1, 2009
• First Submitted That Met QC Criteria: September 1, 2009
• First Posted (Estimate): September 2, 2009

Study Record Updates

• Last Update Posted (Estimate): April 8, 2015
• Last Update Submitted That Met QC Criteria: March 5, 2015
• Last Verified: December 1, 2014

More Information

Terms related to this study

• Keywords: Neuroplasticity; Aging; Motor control; Swallowing; Motor cortex
• Other Study ID Numbers: C6697-M