e. s. kruger, j. a. hoopes , r. j. cordial, and s. li
DESCRIPTION
Error compensation during finger force production after one and four-finger voluntarily fatiguing exercise. E. S. Kruger, J. A. Hoopes , R. J. Cordial, and S. Li. By Kelsey Christensen. Background. Motor Variability Bernstein “repetition without repetition”. Background. Motor Variability - PowerPoint PPT PresentationTRANSCRIPT
Error compensation during finger force
production after one and four-finger
voluntarily fatiguing exercise.
E. S. Kruger, J. A. Hoopes, R. J. Cordial, and S. Li
By Kelsey Christensen
• Motor Variability• Bernstein “repetition without repetition”.
Background
• Motor Variability• Bernstein “repetition without repetition”.
• Degrees of Freedom (DOF)• Number of independent elements in a
system.
Background
• Motor Variability• Bernstein “repetition without repetition”.
• Degrees of Freedom (DOF)• Number of independent elements in a
system.
• DOF Problem/Problem of Motor
Redundancy• How does the CNS select a particular
solution from the infinite number of
solutions?
Background
Introduction• Error Compensation• DOFs work together to accomplish a
given task by compensating for
errors made.
• Utilizing motor variability and
redundant DOFs.
Introduction• Error Compensation• DOFs work together to accomplish a
given task by compensating for
errors made.
• Utilizing motor variability and
redundant DOFs.
• How is error compensation
affected when parts of the
motor system are impaired
(number of DOFs is reduced)?
Methods• Apparatus
• Procedures
• Data Analysis
Methods• Apparatus
• Procedures
• Data Analysis
Methods• Apparatus
• Procedures
• Data Analysis
Procedures• 13 young, healthy adults
• 2 sessions, 2-3 days apart• Index finger fatigued
• All four fingers fatigued
3 6 9
Force (N)
Time (s)
3 6 9
Force (N)
Time (s)
3 6 9
Force (N)
Time (s)
Ftot
FI
FM
FR
FL
Ftot = FI+ FM+ FR+ FL
Methods• Apparatus
• Procedures
• Data Analysis
Data Analysis• Force signals from individual sensors to
analyze force profiles.
• ΣVarFi = sum of the variances of
individual finger forces
• VarFtot = variance of total force
• Error Compensation Index (ECI) = ratio of
ΣVarFi to VarFtot.
From force profiles:
Results
• Variance (A) and Error Compensation Index (B) averaged over entire force ramp and across all subjects.
• Average Error Compensation Index over the 1st, 2nd, and 3rd one-second segments of the ramp phase (seconds 4,5,6).
Discussion
Summary• The CNS is able to utilize the abundant
DOFs to compensate for motor system
impairments to maintain the desired
performance.
• Problem of Motor Redundancy is a GOOD
thing.
• Principle of Abundance – but there is a
limit.