老年人口在近幾年快速成長，人口老化成為全球關注的議題，預防生理功能的退化與提升生活品質也逐漸被重視。其中，老年人的生活品質與日常活動容易受手功能退化影響。由於生理功能的退化，手指協調能力、施力獨立性與力量控制能力會隨著年齡逐漸下降。許多研究建議手部的肌力訓練與手指協調訓練可有效改善手指力量與手指協調能力。過去研究認為老人的動作表現可能與大腦皮質的退化有關。然而，大腦的退化情形與手部協調、控制能力相關的研究較少被討論。
因此本研究的目的希望探討老化對大腦皮質在執行不同手指按壓任務時的活化情形，並比較在不同按壓力量(30%最大力和50%最大力)、按壓順序(順序和隨機)與按壓頻率(1赫茲和1.25赫茲)下大腦皮質的活化表現。本研究招募15位年輕人與15位老年人利用手指按壓評估系統執行不同按壓任務，同時使用近紅外光譜儀收集兩側大腦前額葉與初級動作皮質區之含氧血紅素濃度變化。除此之外，亦會探討大腦活化情形與施力獨立性、普渡手功能測驗之相關性。
其結果發現年輕人的手指施力獨立性與普渡手功能測驗成績皆高於老年人，代表年輕人的手指力量控制能力與精細動作表現皆比老年人來的好。在大腦活化部分，老年人不論在執行30%或50%最大力的力量控制任務時，兩側前額區與初級動作皮質區都有顯著活化且活化程度比年輕人大。在執行目標力量為30%最大力時，老年人與年輕人在對側初級動作皮質區有顯著差異。兩組在執行50%最大力的力量控制任務時，大腦的活化程度皆比在執行30%最大力的力量控制任務大。在大部分的連續按壓動作中，老年人的大腦活化程度比年輕人大，且在照順序按壓，按壓頻率為1.25赫茲時，老年人與年輕人的同側前額葉活化有顯著差異。改變按壓順序對兩組的大腦活化並無顯著影響。改變按壓頻率對年輕組並無顯著影響，但對老年人有顯著影響。除此之外，本研究也發現在手指施力獨立性與兩側前額葉與初級動作皮質區的活化程度有輕度負相關。而普渡手功能測驗的成績與在執行連續按壓動作時的同側前額葉與同側初級動作皮質區有輕度負相關，此外普渡手功能的成績與在執行力量控制任務時兩側前額葉與對側的初級動作皮質區活化情形亦有輕度負相關。代表當動作表現越佳者，大腦活化程度較低。
本研究發現在執行複雜的手指動作時，老年人的大腦活化情形會比年輕人大，此現象推測可能為老化所出現的代償影響。此外，透過較複雜的手指動作，可刺激大腦前額葉與初級動作皮質區產生較大活化。因此，此研究認為透過PETS的按壓訓練不只可以改善手部功能，更可以刺激老年人的大腦的活化情形。在未來的研究中，增加受測者數目及考慮動作困難度有助於了解大腦在執行不同任務下的活化情形。

The elderly population has increased rapidly around the world. Age-related degeneration of hand function disturbs the quality of daily living. Previous studies have demonstrated that finger coordination, force independence, and force variation in elderly adults is worse than that of young adults. Muscle training and finger coordination training are suggested to improve finger force and finger coordination. According to previous studies, age-related changes in the cerebral cortex might explain the deteriorated motor performance exhibited by elderly adults. Insufficient number of studies has compared the influence of aging brain on different finger force control, finger coordination tasks in the elderly adults.
The purposes of the current study are to investigate the age-related changes in the force control and brain activities in different finger pressing tasks, and to examine the influence of different factors on brain activity during finger movements. Fifteen young subjects and fifteen elderly subjects were asked to perform the force ramp tasks (30% and 50% maximal pressing force), and the sequential pressing tasks at different pressing sequences (in order and random pressing ) and frequencies (1Hz and 1.25Hz) with the Pressing Evaluation and Training System (PETS). Near infrared spectroscopy (NIRS) was used to collect the brain activities in the bilateral prefrontal lobe (PFC) and primary motor area (M1) during the finger movements. The index of finger independence, enslaving value (EN value), was calculated to evaluate the force control ability, and the Purdue Pegboard Test was used to examine manual dexterity.
The results showed that the young group had significantly higher EN values and Purdue Pegboard Test scores as compared to the elderly adults, and indicated that the young group had better force independence ability and finger coordination. During the force ramp tasks, the cortical activations in the elderly group were higher than that of the young group in either force level. The effect of aging on the hemodynamic responses were found in the contralateral M1 during the 30% MVC force ramp task. The brain activity increased with the pressing force in both groups. The hemodynamic responses of elderly adults during most sequential pressing tasks were higher as compared to the young adults. The significant activation between groups was found in the ipsilateral PFC in the Seq_1.25Hz. No significant effects of sequence on the cortical activation in both groups. No significant effect of frequency was found in young group but significant effect was found in the elderly group. Additionally, the results demonstrated mildly negative correlations between the EN value and the activation of bilateral PFC and bilateral M1 during the force ramp task. The results also displayed mildly negative correlations between the Purdue Pegboard Test score and the activation of the ipsilateral PFC and the ipsilateral M1 during all sequential pressing tasks. The mildly negative correlations were found between the Purdue Pegboard Test score and the activation in bilateral PFC and contralateral M1 during the force ramp tasks. It suggested that people with better finger coordination and force control ability do not have to activate additional brain areas.
Our findings suggested that elderly adults require additional brain activity to compensate for age-related degeneration in the brain. Complicated pressing tasks can activate the bilateral PFC and M1. In our opinion, PETS is suggested to increase the degree of brain activation during multi-digits movements. In the future, increasing the sampling size and consider the difficulties in the multi-digits pressing task may help to understand the brain activity during different tasks.

1. 國家發展委員會, 中華民國人口推估（105至150年）. 2016.
2. Eli Carmeli, Hagar Patish, and R. Coleman, The Aging Hand. Journal of Gerontology : MEDICAL SCIENCES, 2003. 58 A(2): p. 146-152.
3. Chou, P.-H. and T.-H. Lan, The role of near-infrared spectroscopy in Alzheimer's disease. Journal of Clinical Gerontology and Geriatrics, 2013. 4(2): p. 33-36.
4. Maillet, D. and M.N. Rajah, Association between prefrontal activity and volume change in prefrontal and medial temporal lobes in aging and dementia: a review. Ageing Res Rev, 2013. 12(2): p. 479-89.
5. Burns, A. and S. Iliffe, Alzheimer’s disease. BMJ, 2009. 338.
6. Swanson, A.B., C.G. Hagert, and G. deGroot Swanson, Evaluation of impairment of hand function. The Journal of Hand Surgery, 1983. 8(5): p. 709-722.
7. Incel, N.A., M. Sezgin, I. As, O.B. Cimen, and G. Sahin, The geriatric hand: correlation of hand-muscle function and activity restriction in elderly. Int J Rehabil Res, 2009. 32(3): p. 213-8.
8. Shiffman, L.M., Effects of Aging on Adult Hand Function. The American Journal of Occupational Therapy, 1992. 46(9): p. 785-792.
9. Liu, C.J., D. Marie, A. Fredrick, J. Bertram, K. Utley, and E.E. Fess, Predicting hand function in older adults: evaluations of grip strength, arm curl strength, and manual dexterity. Aging Clin Exp Res, 2016.
10. Mary E Hackel, George A. Wolfe, Sharon M. Bang, and J.S. Canfield, Changes in Hand Function in the Aging Adult as Determined by the Jebsen Test of Hand Function. Physical Therapy, 1992. 72(5): p. 373-377.
11. Bowden, J.L. and P.A. McNulty, The magnitude and rate of reduction in strength, dexterity and sensation in the human hand vary with ageing. Exp Gerontol, 2013. 48(8): p. 756-65.
12. Jones, L.A. and S.J. Lederman, Human hand function. 2006: Oxford University Press.
13. Park, J., Y.-H. Wu, M.M. Lewis, X. Huang, and M.L. Latash, Changes in multifinger interaction and coordination in Parkinson's disease. Journal of neurophysiology, 2012. 108(3): p. 915-924.
14. Hsu, H.Y., L.C. Kuo, H.Y. Chiu, I.-M. Jou, and F.C. Su, Functional sensibility assessment. Part II: Effects of sensory improvement on precise pinch force modulation after transverse carpal tunnel release. Journal of Orthopaedic Research, 2009. 27(11): p. 1534-1539.
15. Chiu, H.Y., H.Y. Hsu, L.C. Kuo, J.H. Chang, and F.C. Su, Functional sensibility assessment. Part I: develop a reliable apparatus to assess momentary pinch force control. J Orthop Res, 2009. 27(8): p. 1116-21.
16. Chen, P.T., I.M. Jou, C.J. Lin, H.F. Chieh, L.C. Kuo, and F.C. Su, Is the Control of Applied Digital Forces During Natural Five-digit Grasping Affected by Carpal Tunnel Syndrome? Clin Orthop Relat Res, 2015. 473(7): p. 2371-82.
17. Chen, P.-T., C.-J. Lin, I.-M. Jou, H.-F. Chieh, F.-C. Su, and L.-C. Kuo, One digit interruption: the altered force patterns during functionally cylindrical grasping tasks in patients with trigger digits. PloS one, 2013. 8(12): p. e83632.
18. Diermayr, G., T.L. McIsaac, and A.M. Gordon, Finger force coordination underlying object manipulation in the elderly - a mini-review. Gerontology, 2011. 57(3): p. 217-27.
19. Shinohara, M., J.P. Scholz, V.M. Zatsiorsky, and M.L. Latash, Finger interaction during accurate multi-finger force production tasks in young and elderly persons. Experimental Brain Research, 2004. 156(3): p. 282-292.
20. Ranganathan, V.K., V. Siemionow, V. Sahgal, and G.H. Yue, Effects of aging on hand function. J Am Geriatr Soc, 2001. 49(11): p. 1478-84.
21. Voelcker-Rehage, C. and J.L. Alberts, Age-related changes in grasping force modulation. Exp Brain Res, 2005. 166(1): p. 61-70.
22. Vieluf, S., J.-J. Temprado, E. Berton, V.K. Jirsa, and R. Sleimen-Malkoun, Effects of task and age on the magnitude and structure of force fluctuations: insights into underlying neuro-behavioral processes. BMC neuroscience, 2015. 16(1): p. 12.
23. Kinoshita, H. and P.R. Francis, A comparison of prehension force control in young and elderly individuals. European journal of applied physiology and occupational physiology, 1996. 74(5): p. 450-460.
24. Keogh, J., S. Morrison, and R. Barrett, Age-related differences in inter-digit coupling during finger pinching. European journal of applied physiology, 2006. 97(1): p. 76-88.
25. Laidlaw, D.H., K.W. Kornatz, D.A. Keen, S. Suzuki, and R.M. Enoka, Strength training improves the steadiness of slow lengthening contractions performed by old adults. Journal of Applied Physiology, 1999. 87(5): p. 1786-1795.
26. Olafsdottir, H.B., V.M. Zatsiorsky, and M.L. Latash, The effects of strength training on finger strength and hand dexterity in healthy elderly individuals. J Appl Physiol (1985), 2008. 105(4): p. 1166-78.
27. Chen, X.-P., Y.-M. Lu, and J. Zhang, Intervention study of finger-movement exercises and finger weight-lift training for improvement of handgrip strength among the very elderly. International Journal of Nursing Sciences, 2014. 1(2): p. 165-170.
28. Ranganathan, V.K., V. Siemionow, V. Sahgal, J.Z. Liu, and G.H. Yue, Skilled finger movement exercise improves hand function. J Gerontol A Biol Sci Med Sci, 2001. 56(8): p. M518-22.
29. Tsai, M.-F., 中風病人手指創新復健器. 成功大學生物醫學工程學系學位論文, 2016: p. 1-94.
30. Martin, S.T. and M. Kessler, Neurologic interventions for physical therapy. 2015: Elsevier Health Sciences.
31. Anwar, A., M. Muthalib, S. Perrey, A. Galka, O. Granert, S. Wolff, U. Heute, G. Deuschl, J. Raethjen, and M. Muthuraman, Effective connectivity of cortical sensorimotor networks during finger movement tasks: a simultaneous fNIRS, fMRI, EEG study. Brain topography, 2016. 29(5): p. 645-660.
32. Leff, D.R., F. Orihuela-Espina, C.E. Elwell, T. Athanasiou, D.T. Delpy, A.W. Darzi, and G.Z. Yang, Assessment of the cerebral cortex during motor task behaviours in adults: a systematic review of functional near infrared spectroscopy (fNIRS) studies. Neuroimage, 2011. 54(4): p. 2922-36.
33. Luo, L., Principles of Neurobiology. 2015: Garland Science.
34. Mehagnoul-Schipper, D.J., B.F. van der Kallen, W.N. Colier, M.C. van der Sluijs, L.J. van Erning, H.O. Thijssen, B. Oeseburg, W.H. Hoefnagels, and R.W. Jansen, Simultaneous measurements of cerebral oxygenation changes during brain activation by near-infrared spectroscopy and functional magnetic resonance imaging in healthy young and elderly subjects. Hum Brain Mapp, 2002. 16(1): p. 14-23.
35. Ferrari, M. and V. Quaresima, A brief review on the history of human functional near-infrared spectroscopy (fNIRS) development and fields of application. Neuroimage, 2012. 63(2): p. 921-35.
36. Kuboyama N, N.T., Shibuya K, Machida K, Ogaki T., The Effect of Maximal Finger Tapping on Cerebral Activation. J Physiol Anthropol Appl Human Sci, 2004. 23(4): p. 105-10.
37. Sato, T., M. Ito, T. Suto, M. Kameyama, M. Suda, Y. Yamagishi, A. Ohshima, T. Uehara, M. Fukuda, and M. Mikuni, Time courses of brain activation and their implications for function: a multichannel near-infrared spectroscopy study during finger tapping. Neurosci Res, 2007. 58(3): p. 297-304.
38. Takeda, K., Y. Gomi, I. Imai, N. Shimoda, M. Hiwatari, and H. Kato, Shift of motor activation areas during recovery from hemiparesis after cerebral infarction: a longitudinal study with near-infrared spectroscopy. Neurosci Res, 2007. 59(2): p. 136-44.
39. Ohsugi, H., S. Ohgi, K. Shigemori, and E.B. Schneider, Differences in dual-task performance and prefrontal cortex activation between younger and older adults. BMC Neurosci, 2013. 14: p. 10.
40. Kashou, N.H., B.M. Giacherio, R.W. Nahhas, and S.R. Jadcherla, Hand-grasping and finger tapping induced similar functional near-infrared spectroscopy cortical responses. Neurophotonics, 2016. 3(2): p. 025006.
41. Shibuya, K., N. Kuboyama, and J. Tanaka, Changes in ipsilateral motor cortex activity during a unilateral isometric finger task are dependent on the muscle contraction force. Physiol Meas, 2014. 35(3): p. 417-28.
42. Shibuya, K., The activity of the primary motor cortex ipsilateral to the exercising hand decreases during repetitive handgrip exercise. Physiol Meas, 2011. 32(12): p. 1929-39.
43. Dai, T., J. Liu, V. Sahgal, R. Brown, and G. Yue, Relationship between muscle output and functional MRI-measured brain activation. Experimental Brain Research, 2001. 140(3): p. 290-300.
44. Holper, L., M. Biallas, and M. Wolf, Task complexity relates to activation of cortical motor areas during uni-and bimanual performance: a functional NIRS study. Neuroimage, 2009. 46(4): p. 1105-1113.
45. Okamoto, M., H. Dan, K. Shimizu, K. Takeo, T. Amita, I. Oda, I. Konishi, K. Sakamoto, S. Isobe, T. Suzuki, K. Kohyama, and I. Dan, Multimodal assessment of cortical activation during apple peeling by NIRS and fMRI. Neuroimage, 2004. 21(4): p. 1275-88.
46. Carius, D., C. Andra, M. Clauss, P. Ragert, M. Bunk, and J. Mehnert, Hemodynamic Response Alteration As a Function of Task Complexity and Expertise-An fNIRS Study in Jugglers. Front Hum Neurosci, 2016. 10: p. 126.
47. Mirelman, A., I. Maidan, H. Bernad-Elazari, S. Shustack, N. Giladi, and J.M. Hausdorff, Effects of aging on prefrontal brain activation during challenging walking conditions. Brain Cogn, 2017. 115: p. 41-46.
48. Technologies, N.M. NIRx. 2017/05/08 [cited 2017 06/13]; Available from: http://nirx.net/nirscout/.
49. Guideline thirteen: guidelines for standard electrode position nomenclature. American Electroencephalographic Society. Journal of clinical neurophysiology, 1994. 11(1): p. 111-113.
50. van Duinen, H., R. Renken, N.M. Maurits, and I. Zijdewind, Relation between muscle and brain activity during isometric contractions of the first dorsal interosseus muscle. Hum Brain Mapp, 2008. 29(3): p. 281-99.
51. Wu, Y.-H., T.S. Truglio, V.M. Zatsiorsky, and M.L. Latash, Learning to Combine High Variability With High Precision: Lack of Transfer to a Different Task. Journal of motor behavior, 2015. 47(2): p. 153-165.
52. Wilhelm, L.A., J.R. Martin, M.L. Latash, and V.M. Zatsiorsky, Finger enslaving in the dominant and non-dominant hand. Human movement science, 2014. 33: p. 185-193.
53. Lin, T.Y., J.S. Wu, L.L. Lin, T.C. Ho, P.Y. Lin, and J.J. Chen, Assessments of Muscle Oxygenation and Cortical Activity Using Functional Near-infrared Spectroscopy in Healthy Adults During Hybrid Activation. IEEE Trans Neural Syst Rehabil Eng, 2016. 24(1): p. 1-9.
54. Koenraadt, K.L., J. Duysens, M. Smeenk, and N.L. Keijsers, Multi-channel NIRS of the primary motor cortex to discriminate hand from foot activity. J Neural Eng, 2012. 9(4): p. 046010.
55. Colier, W.N.J.M., V. Quaresima, B. Oeseburg, and M. Ferrari, Human motor-cortex oxygenation changes induced by cyclic coupled movements of hand and foot. Exp Brain Res, 1999. 129: p. 457-461.
56. Duncan, A., J.H. Meek, M. Clemence, C.E. Elwell, P. Fallon, L. Tyszczuk, M. Cope, and D.T. Delpy, Measurement of cranial optical path length as a function of age using phase resolved near infrared spectroscopy. Pediatric research, 1996. 39(5): p. 889-894.
57. Sato, H., Y. Fuchino, M. Kiguchi, T. Katura, A. Maki, T. Yoro, and H. Koizumi, Intersubject variability of near-infrared spectroscopy signals during sensorimotor cortex activation. Journal of biomedical optics, 2005. 10(4): p. 044001-044001-10.
58. Pei-Yi Lin, Sang-I Lin, and J.-J.J. Chen, Functional Near Infrared Spectroscopy Study of Age-related difference in corticaal activation patterns during cycling with speed feedback. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2012. 20(1): p. 78-84.
59. Kuboyama, N. and K. Shibuya, Ipsi- and contralateral frontal cortex oxygenation during handgrip task does not follow decrease on maximal force output. J Physiol Anthropol, 2015. 34: p. 37.
60. Galganski, M.E., A.J. Fuglevand, and R.M. Enoka, Reduced control of motor output in a human hand muscle of elderly subjects during submaximal contractions. Journal of neurophysiology, 1993. 69(6): p. 2108-2115.
61. Riecker, A., K. Groschel, H. Ackermann, C. Steinbrink, O. Witte, and A. Kastrup, Functional significance of age-related differences in motor activation patterns. Neuroimage, 2006. 32(3): p. 1345-54.
62. Noble, J.W., J.J. Eng, K.J. Kokotilo, and L.A. Boyd, Aging effects on the control of grip force magnitude: an fMRI study. Experimental gerontology, 2011. 46(6): p. 453-461.
63. Ward, N. and R. Frackowiak, Age‐related changes in the neural correlates of motor performance. Brain, 2003. 126(4): p. 873-888.
64. Mattay, V.S., F. Fera, A. Tessitore, A.R. Hariri, S. Das, J.H. Callicott, and D.R. Weinberger, Neurophysiological correlates of age-related changes in human motor function. Neurology, 2002. 58(4): p. 630-635.
65. Chiang, H., S. Slobounov, and W. Ray, Practice-related modulations of force enslaving and cortical activity as revealed by EEG. Clinical neurophysiology, 2004. 115(5): p. 1033-1043.
66. Kuboyama, N., T. Nabetani, K. Shibuya, K. Machida, and T. Ogaki, Relationship between Cerebral Activity and Movement Frequency of Maximal Finger Tapping. Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science, 2005. 24(3): p. 201-208.