日常生活中我們經常從事抓握或提取的動作，大腦如何知道讓肌肉產生多少力氣，則需依賴之前的學習經驗及手部的感覺回饋，亦即需要所謂的前饋機制及回饋機制。雙手對於人類之所以重要，除了其可做出複雜且精密的動作外，手部敏感的感覺功能更是一大因素，完整的手部感覺功能除了正確接收感覺訊息外，也是協助雙手操作各種物體及做出各類動作的基本條件。而感覺功能有缺失的雙手不僅會直接影響其接收外在感覺訊息之正確外，其輸出力量大小亦會受到相對影響。
本研究的第一部分目的在於設計一抓握設備內含荷重規、加速規，利用抓握提舉測試偵測到的最大抓握力量及握力/負重比值來探討感覺訊息在抓握控制中所扮演的角色。結果得到此設備在不同時間點所測得之即時握力/負重比值，在提舉不同重量及分別使用左右手的情況下，其一致性高達0.96-0.98。
第二部分施測者將受試者之手指塗以麻醉藥物，使其感覺暫時喪失外，來探討手指麻醉前後握力的控制。結果發現病患在麻醉後，最大握力及握力/負重比值在提舉過程中顯然增加。由此實驗可證明由感覺受器得到不足的感覺回饋時，無法誘發正常的抓握反應，受試者於麻醉情境下，為避免物體滑落，會產生較大的抓握力量執行抓握提舉動作。
此研究的第三部份收集正中神經受損的個案並與正常個案互做抓握效益比較，由於神經壓迫患者其有可能僅有髓鞘受損或軸突的壓迫導致感覺傳遞速度減緩或是訊號傳遞強度變弱，但卻不至於造成感覺的完全喪失。結果得到腕隧道症候群病患因神經壓迫引起感覺受損，顯著影響病患執行抓握提舉時的握力控制及效益。
第四部份則探討正中神經受損的個案接受橫腕韌帶切除術後所產生的抓握效益改變。結果證實病患於術後感覺功能顯著進步且在執行功能活動上也明顯能精準的控制握力的調整。
神經切斷後雖經修復，指神經會經過兩星期的退化過程再以每天一釐米的速度生長。在第五部份，實驗的目的在於探討神經再生過程中，感覺功能的進步是否會影響手部執行抓握提舉動作的控制。實驗結果證實確實隨著病患的兩點辨別覺及壓力閥值的進步，個案在抓握效益及力量控制上也有較好的調控，且具有統計學上顯著意義。
由本實驗所得到的結果，可支持感覺功能對於手部抓握控制扮演相對重要的角色。並利用此結果提供臨床醫療人員在給予手指感覺功能異常者感覺再教育治療之實證基礎，且幫助神經受損患者免於手部功能惡化的可能性。

Hands play an important role in human life because of their complicated movements and sensory function. Intact sensory function of hands not only helps to receive sensory input precisely, but also assist two hands to manipulate various objects and control every kind of skillful movement. Precision grip is an experimental model for skilled movement control. The purpose of this study is to analyze how the cutaneous sensation of grasping digits contributed to precise pinch force control according to the momentum-induced force change in the pinch-holding-up task.
The instrument that incorporated a force sensor and an accelerometer was designed to monitor kinematic and kinetics data in pinch-holding-up task, but the reproducibility and variance of the instrument were not reported. Therefore, in the first part of this study (chapter 2), we developed a reliable instrument to assessment of real-time force ratio between FPpeak and FLmax for pinch-holding-up activity. The result indicated high intra-class correlation (0.96 to 0.98) of detected force ratio among the three tests.
Muscles are tightly controlled by sensory message according different phases during the course of pinch-holding-up task. If the sensory system is disrupted, the brain cannot integrate sensory information and program an appropriate default response. The objective of the second part (Chapter 3) was to analyze the effect of induced mild impaired sensation of grasping digits on the precision control of pinch force modulation during the manipulation of mechanically predictable loads. The results revealed that mild impairment of sensation affected significantly on the parameters of peak pinch force, baseline pinch force and force ratio (p<0.05).
The objective of the third part (Chapter 4) was to analyze whether the carpal tunnel syndrome patients sustained persisted paraesthesia would induce long-lasting modification of cortical neural representation and got an adaptive strategy in the programming of precision grip. Results proved that patients with unspecific severity of sensory disturbance could not trigger appropriate motor output according to actual force changes than subjects of control group.
However, the quality of pinch force regarding with improvement of sensory status of carpal tunnel syndrome followed transverse carpal ligament (TCL) transaction still not to be investigated. In the fourth part (Chapter 5), we studied if the precision and efficiency of pinch grip control would get better through improvement of sensation followed minimally invasive incision of TCL. The results showed that improvement in the sensory function of median nerve soon after release of carpal tunnel ligament, and illustrated the precision force control and better force ratio in manual activity.
A large group of patients with sensory impaired in clinic is the patients with nerve repair. The fifth part of this study (Chapter6) was designed to be explored whether the better the discriminative sensation followed nerve regeneration, the better control of pinch force regulation in responding to unexpected disturbances. The results illustrated that effect of sensory improvement on more precision of motor control during fine manipulation followed by nerve regeneration.
The results of the present study proved that cutaneous sensation contributed an important role in pinch force control, either in the condition of induced impair sensation or the carpal tunnel syndrome patients.

References
Almquist, E., & Eeg-Olofsson, O.. Sensory-nerve-conduction velocity and two-point discrimmination in sutured nerves. J Bone Joint Surg Am, 52(4), 791-796, 1970
Augurelle, A. S., Smith, A. M., Lejeune, T., & Thonnard, J. L.. Importance of cutaneous feedback in maintaining a secure grip during manipulation of hand-held objects. J Neurophysiol, 89(2), 665-671, 2003
Cole, K. J., & Abbs, J. H.. Grip force adjustments evoked by load force perturbations of a grasped object. J Neurophysiol, 60(4), 1513-1522, 1988
Cole, K. J., Steyers, C. M., & Graybill, E. K.. The effects of graded compression of the median nerve in the carpal canal on grip force. Exp Brain Res, 148(2), 150-157, 2003
Dellon, A. L.. Evaluation of sensibility and re-education of sensation in the hand. Baltimore: Williams and Wilkins, 1981
Ebied, A. M., Kemp, G. J., & Frostick, S. P.. The role of cutaneous sensation in the motor function of the hand. J Orthop Res, 22(4), 862-866, 2004
Eliasson, A. C., Forssberg, H., Ikuta, K., Apel, I., Westling, G., & Johansson, R.. Development of human precision grip. V. anticipatory and triggered grip actions during sudden loading. Exp Brain Res, 106(3), 425-433, 1995
Flanagan, J. R., & Wing, A. M.. The stability of precision grip forces during cyclic arm movements with a hand-held load. Exp Brain Res, 105(3), 455-464, 1995
Forssberg, H., Eliasson, A. C., Kinoshita, H., Johansson, R. S., & Westling, G.. Development of human precision grip. I: Basic coordination of force. Exp Brain Res, 85(2), 451-457, 1991
Forssberg, H., Eliasson, A. C., Kinoshita, H., Westling, G., & Johansson, R. S.. Development of human precision grip. IV. Tactile adaptation of isometric finger forces to the frictional condition. Exp Brain Res, 104(2), 323-330, 1995
Forssberg, H., Kinoshita, H., Eliasson, A. C., Johansson, R. S., Westling, G., & Gordon, A. M.. Development of human precision grip. II. Anticipatory control of isometric forces targeted for object's weight. Exp Brain Res, 90(2), 393-398, 1992
Gelberman, R. H., Szabo, R. M., Williamson, R. V., & Dimick, M. P.. Sensibility testing in peripheral-nerve compression syndromes. An experimental study in humans. J Bone Joint Surg Am, 65(5), 632-638, 1983
Gordon, A. M., Forssberg, H., Johansson, R. S., & Westling, G.. The integration of haptically acquired size information in the programming of precision grip. Exp Brain Res, 83(3), 483-488, 1991
Hager-Ross, C., & Johansson, R. S.. Nondigital afferent input in reactive control of fingertip forces during precision grip. Exp Brain Res, 110(1), 131-141, 1996
Herron, D. M., Gagner, M., Kenyon, T. L., & Swanstrom, L. L.. The minimally invasive surgical suite enters the 21st century. A discussion of critical design elements. Surg Endosc, 15(4), 415-422, 2001
Hunter JM, Schneider LH, Mackin EJ, & Callahan AD.. Rehabiliation of the hand: surgery and therapy (3rd ed.). St. Louis: Mosby, 1990
Jimenez, D. F., Gibbs, S. R., & Clapper, A. T.. Endoscopic treatment of carpal tunnel syndrome: a critical review. J Neurosurg, 88(5), 817-826, 1998
Johansson, R. S., & Cole, K. J.. Sensory-motor coordination during grasping and manipulative actions. Curr Opin Neurobiol, 2(6), 815-823, 1992
Johansson, R. S., Hager, C., & Riso, R.. Somatosensory control of precision grip during unpredictable pulling loads. II. Changes in load force rate. Exp Brain Res, 89(1), 192-203, 1992
Johansson, R. S., Hger, C., & Backstrom, L.. Somatosensory control of precision grip during unpredictable pulling loads. III. Impairments during digital anesthesia. Exp Brain Res, 89(1), 204-213, 1992
Johansson, R. S., Riso, R., Hager, C., & Backstrom, L.. Somatosensory control of precision grip during unpredictable pulling loads. I. Changes in load force amplitude. Exp Brain Res, 89(1), 181-191, 1992
Johansson, R. S., & Westling, G.. Roles of glabrous skin receptors and sensorimotor memory in automatic control of precision grip when lifting rougher or more slippery objects. Exp Brain Res, 56(3), 550-564, 1984
Johansson, R. S., & Westling, G.. Signals in tactile afferents from the fingers eliciting adaptive motor responses during precision grip. Exp Brain Res, 66(1), 141-154, 1987
Johansson, R. S., & Westling, G.. Coordinated isometric muscle commands adequately and erroneously programmed for the weight during lifting task with precision grip. Exp Brain Res, 71(1), 59-71, 1988
Katz, J. N., Keller, R. B., Fossel, A. H., Punnett, L., Bessette, L., Simmons, B. P., et al.. Predictors of return to work following carpal tunnel release. Am J Ind Med, 31(1), 85-91, 1997
Katz, J. N., & Simmons, B. P.. Clinical practice. Carpal tunnel syndrome. N Engl J Med, 346(23), 1807-1812, 2002
Kawato, M., Kuroda, T., Imamizu, H., Nakano, E., Miyauchi, S., & Yoshioka, T.. Internal forward models in the cerebellum: fMRI study on grip force and load force coupling. Prog Brain Res, 142, 171-188, 2003
Keir, P. J., Bach, J. M., & Rempel, D. M.. Fingertip loading and carpal tunnel pressure: differences between a pinching and a pressing task. J Orthop Res, 16(1), 112-115, 1998
Klein, R. D., Kotsis, S. V., & Chung, K. C.. Open carpal tunnel release using a 1-centimeter incision: technique and outcomes for 104 patients. Plast Reconstr Surg, 111(5), 1616-1622, 2003
Krag, C., & Rasmussen, K. B.. The neurovascular island flap for defective sensibility of the thumb. J Bone Joint Surg Br, 57(4), 495-499, 1975
Macefield, V. G., & Johansson, R. S.. Control of grip force during restraint of an object held between finger and thumb: responses of muscle and joint afferents from the digits. Exp Brain Res, 108(1), 172-184, 1996
Nakada, M., & Uchida, H.. Case study of a five-stage sensory reeducation program. J Hand Ther, 10(3), 232-239, 1997
Nishimura, A., Ogura, T., Hase, H., Makinodan, A., Hojo, T., Katsumi, Y., et al.. A correlative electrophysiologic study of nerve fiber involvement in carpal tunnel syndrome using current perception thresholds. Clin Neurophysiol, 115(8), 1921-1924, 2004
Nowak, D. A., Glasauer, S., & Hermsdorfer, J.. How predictive is grip force control in the complete absence of somatosensory feedback? Brain, 127(Pt 1), 182-192, 2004
Nowak, D. A., & Hermsdorfer, J.. Digit cooling influences grasp efficiency during manipulative tasks. Eur J Appl Physiol, 89(2), 127-133, 2003a
Nowak, D. A., & Hermsdorfer, J.. Selective deficits of grip force control during object manipulation in patients with reduced sensibility of the grasping digits. Neurosci Res, 47(1), 65-72, 2003b
Nowak, D. A., Hermsdorfer, J., Glasauer, S., Philipp, J., Meyer, L., & Mai, N.. The effects of digital anaesthesia on predictive grip force adjustments during vertical movements of a grasped object. Eur J Neurosci, 14(4), 756-762, 2001
Ogura, T., Akiyo, N., Kubo, T., Kira, Y., Aramaki, S., & Nakanishi, F.. The relationship between nerve conduction study and clinical grading of carpal tunnel syndrome. J Orthop Surg (Hong Kong), 11(2), 190-193, 2003
R.Kandel, E., Schwartz, J. H., & M.Jessell, T.. Principles of neural science (fourth ed.). New York: McGraw-Hill, 2000
Radwin, R. G., Sesto, M. E., & Zachary, S. V.. Functional tests to quantify recovery following carpal tunnel release. J Bone Joint Surg Am, 86-A(12), 2614-2620, 2004
Reale, F., Ginanneschi, F., Sicurelli, F., & Mondelli, M.. Protocol of outcome evaluation for surgical release of carpal tunnel syndrome. Neurosurgery, 53(2), 343-350; discussion 350-341, 2003
Ross, M. A., & Kimura, J.. AAEM case report #2: the carpal tunnel syndrome. Muscle Nerve, 18(6), 567-573, 1995
Shieh, S. J., Chiu, H. Y., & Hsu, H. Y.. Long-term effects of sensory reeducation following digital replantation and revascularization. Microsurgery, 18(5), 334-336, 1998
Shieh, S. J., Chiu, H. Y., Lee, J. W., & Hsu, H. Y.. Evaluation of the effectiveness of sensory reeducation following digital replantation and revascularization. Microsurgery, 16(8), 578-582, 1995
Thonnard, J., Saels, P., Van den Bergh, P., & Lejeune, T.. Effects of chronic median nerve compression at the wrist on sensation and manual skills. Exp Brain Res, 128(1-2), 61-64, 1999
Westling, G., & Johansson, R. S.. Factors influencing the force control during precision grip. Exp Brain Res, 53(2), 277-284, 1984
Westling, G., & Johansson, R. S.. Responses in glabrous skin mechanoreceptors during precision grip in humans. Exp Brain Res, 66(1), 128-140, 1987
Wheat, H. E., Salo, L. M., & Goodwin, A. W.. Human ability to scale and discriminate forces typical of those occurring during grasp and manipulation. J Neurosci, 24(13), 3394-3401, 2004
Winter, D. A.. Biomechanics and motor control of human movement (2nd ed.). New York: Wiley, 1990
Witney, A. G., Wing, A., Thonnard, J. L., & Smith, A. M.. The cutaneous contribution to adaptive precision grip. Trends Neurosci, 27(10), 637-643, 2004