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| Author | Park, J.; Pazin, N.; Friedman, J.; Zatsiorsky, V.M.; Latash, M.L. | ||||
| Title | Mechanical properties of the human hand digits: Age-related differences | Type | Journal Article | ||
| Year | 2014 | Publication  |
Clinical Biomechanics | Abbreviated Journal | |
| Volume | 29 | Issue | 2 | Pages | 129–137 |
| Keywords | hand; aging; friction; apparent stiffness; damping | ||||
| Abstract | Background Mechanical properties of human digits may have significant implications for the hand function. We quantified several mechanical characteristics of individual digits in young and older adults. Methods Digit tip friction was measured at several normal force values using a method of induced relative motion between the digit tip and the object surface. A modified quick-release paradigm was used to estimate digit apparent stiffness, damping, and inertial parameters. The subjects grasped a vertical handle instrumented with force/moment sensors using a prismatic grasp with four digits; the handle was fixed to the table. Unexpectedly, one of the sensors yielded leading to a quick displacement of the corresponding digit. A second-order, linear model was used to fit the force/displacement data. Findings Friction of the digit pads was significantly lower in older adults. The apparent stiffness coefficient values were higher while the damping coefficients were lower in older adults leading to lower damping ratio. The damping ratio was above unity for most data in young adults and below unity for older adults. Quick release of a digit led to force changes in other digits of the hand, likely due to inertial hand properties. These phenomena of “mechanical enslaving” were smaller in older adults although no significant difference was found in the inertial parameter in the two groups. Interpretations The decreased friction and damping ratio present challenges for the control of everyday prehensile tasks. They may lead to excessive digit forces and low stability of the grasped object. |
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| ISSN | 0268-0033 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 73 | |||
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| Author | Dempsey-Jones, H.; Wesselink, D.B.; Friedman, J.; Makin, T.R. | ||||
| Title | Organized Toe Maps in Extreme Foot Users | Type | Journal Article | ||
| Year | 2019 | Publication |
Cell Reports | Abbreviated Journal | Cell Reports |
| Volume | 28 | Issue | 11 | Pages | 2748-2756.e4 |
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| Abstract | Although the fine-grained features of topographic maps in the somatosensory cortex can be shaped by everyday experience, it is unknown whether behavior can support the expression of somatotopic maps where they do not typically occur. Unlike the fingers, represented in all primates, individuated toe maps have only been found in non-human primates. Using 1-mm resolution fMRI, we identify organized toe maps in two individuals born without either upper limb who use their feet to substitute missing hand function and even support their profession as foot artists. We demonstrate that the ordering and structure of the artists’ toe representation mimics typical hand representation. We further reveal “hand-like” features of activity patterns, not only in the foot area but also similarly in the missing hand area. We suggest humans may have an innate capacity for forming additional topographic maps that can be expressed with appropriate experience. | ||||
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| Publisher | Elsevier | Place of Publication | Editor | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 2211-1247 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | doi: 10.1016/j.celrep.2019.08.027 | Approved | no | ||
| Call Number | Serial | 99 | |||
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| Author | Raveh, E.; Friedman, J.; Portnoy, S. | ||||
| Title | Visuomotor behaviors and performance in a dual-task paradigm with and without vibrotactile feedback when using a myoelectric controlled hand | Type | Journal Article | ||
| Year | 2018 | Publication |
Assistive Technology | Abbreviated Journal | Assistive Technology |
| Volume | 30 | Issue | Pages | 274-280 | |
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1040-0435 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 85 | |||
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| Author | Raveh, E.; Portnoy, S.; Friedman, J. | ||||
| Title | Myoelectric Prosthesis Users Improve Performance Time and Accuracy Using Vibrotactile Feedback When Visual Feedback Is Disturbed | Type | Journal Article | ||
| Year | 2018 | Publication |
Archives of Physical Medicine and Rehabilitation | Abbreviated Journal | Arch Phys Med Rehabil |
| Volume | 99 | Issue | 11 | Pages | 2263-2270 |
| Keywords | Amputation; Prosthesis; Rehabilitation; Sensory feedback; Visual feedback | ||||
| Abstract | OBJECTIVE: To evaluate the effects of adding vibrotactile feedback (VTF) in myoelectric prosthesis users during performance of a functional task when visual feedback is disturbed. DESIGN: A repeated-measures design with a counter-balanced order of 3 conditions. SETTING: Laboratory setting. PARTICIPANTS: Transradial amputees using a myoelectric prosthesis with normal or corrected eyesight (N=12, median age 65+/-13y). Exclusion criteria were orthopedic or neurologic problems. INTERVENTIONS: All participants performed the modified Box and Blocks Test, grasping and manipulating 16 blocks over a partition using their myoelectric prosthesis. This was performed 3 times: in full light, in a dark room without VTF, and in a dark room with VTF. MAIN OUTCOME MEASURES: Performance time, that is, the time needed to transfer 1 block, and accuracy during performance, measured by number of empty grips, empty transitions with no block and block drops from the hand. RESULTS: Significant differences were found in all outcome measures when VTF was added, with improved performance time (4.2 vs 5.3s) and a reduced number of grasping errors (3.0 vs 6.5 empty grips, 1.5 vs 4 empty transitions, 2.0 vs 4.5 block drops). CONCLUSIONS: Adding VTF to myoelectric prosthesis users has positive effects on performance time and accuracy when visual feedback is disturbed. | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0003-9993 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:29935153 | Approved | no | ||
| Call Number | Serial | 96 | |||
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| Author | Portnoy, S.; Mimouni-Bloch, A.; Rosenberg, L.; Offek, H.; Berman, T.; Kochavi, M.; Orman, G.; Friedman, J. | ||||
| Title | Graphical Product Quality and Muscle Activity in Children With Mild Disabilities Drawing on a Horizontally or Vertically Oriented Tablet | Type | Journal Article | ||
| Year | 2018 | Publication |
American Journal of Occupational Therapy | Abbreviated Journal | Am J Occup Ther |
| Volume | 72 | Issue | 6 | Pages | 1-7 |
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| Abstract | OBJECTIVE. We compared performance level and muscle activity patterns during shape copying and tracing in two positions, while sitting at a desk and while standing in front of a wall, between typically developing (TD) preschool children and children with mild disabilities (MD). METHOD. Twenty-two TD children (8 boys, 14 girls; mean [M] age 5 5.2 yr, standard deviation [SD] 5 0.1) and 13 children with MD (9 boys, 4 girls; M age 5 4.9 yr, SD 5 0.5) participated in this study. RESULTS. The children performed faster and smoother movements when copying shapes on the vertical surface, with no reduction of accuracy, than on the horizontal surface. Children with MD exerted their upper trapezius while performing the short tasks on the vertical surface compared with their muscle activity on the horizontal surface. CONCLUSION. Incorporating short copying or drawing tasks on a vertical surface may increase the control of proximal muscles and ease graphomotor performance in children with MD. |
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| ISSN | 0272-9490 | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Penn State @ write.to.jason @ | Serial | 91 | ||
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