Differential role for the striatum and cerebellum in response to novel movements using a motor learning paradigm.

The aim of this pilot study was to examine the role of the striatum and cerebellum in the adaptation to a novel movement within a sequence of practiced movements using a motor learning paradigm. The performance of patients in the early or advanced stages of Parkinson's disease (PD) and of patients with damage to the cerebellum (CE) was compared, respectively to a group of aged and young matched controls on an adapted version of the Mirror-Tracing Test. In this task, subjects were required to trace a series of complex figures in two conditions: (1) a Practiced condition, in which the figures were composed of the juxtaposition of three simple designs that were extensively practiced before; and (2) a Mixed condition in which triads were created by replacing the last simple figure of the triads in the Practiced condition by a new simple figure that had never been traced individually before. Results showed that all clinical groups were slower than controls at tracing the Practiced triads. Most interestingly, however, only patients in the advanced stages of PD showed increased completion time to trace the triads in the Mixed condition. This suggests that a bilateral striatal dysfunction affects the ability to adapt to a novel motion within a sequence of practiced movements. Although exploratory, these results support a functional dissociation between the striatum and cerebellum in acquiring visuomotor skilled behaviors.     

Role and value of laparoscopic training devices in assessing nondominant and two-handed dexterity

Background and objectives: To determine improvement in hand dexterity with targeted laparoscopic skill exercises desirable for use in the operating rooms among in-training laparoscopic gynaecological surgeons and medical students. Design: Cross-sectional study with paired analysis. Setting: Kiel School of Gynaecological Endoscopy and Reproductive Medicine, Germany, between February and April 2005. Subjects: Twenty third-year medical students and 20 in-training gynaecological endoscopic surgeons from various parts of the world. Interventions: Demonstration and explanation of a set of five laparoscopic skill exercises desirable for use in the operating rooms before administering a pretest. This was followed by voluntary practice of these exercises for at least 10 times over 1 day. The posttest was performed the next day once the participant was comfortable performing the skill. Pre- and posttest assessments were conducted by independent supervisors. Main outcome measures: Time to completion of tasks with minimal errors. Results: There was significant reduction in mean time for all the laparoscopic skill exercises performed with dominant, nondominant, and both hands, before and after the training and practice (p-value <0.01; paired t-test). Moderate to high correlation (0.617–0.901) was seen with the intermediate and complex/difficult tasks, whereas low correlation was seen with the simple/easy task (0.200–0.336). Medical students and gynaecologists both showed improvement in performance from pretest to posttest in terms of reduction in mean time taken to perform all the tasks with minimal errors. Conclusions: Simple laparoscopic training devices can substantially help an individual hand’s improvement and acquisition of laparoscopic skills. Simple laparoscopic training devices along with animal models will continue to provide an efficient and effective environment for learning and teaching laparoscopic surgical skills. With this training, performance improves progressively with practice.     

口腔技能竞赛对口腔实践教学质量的影响研究

本研究结合内蒙古医科大学口腔医学院参加口腔技能竞赛的经验,分析总结出技能竞赛所折射出的教学问题,并提炼出夯实理论基础和培养临床思维是基础、贯穿无菌观念和保持标准体位和姿势是关键、规范操作标准与强化手部技能是重点的教学策略。通过参加技能竞赛,提高了学生对口腔实践技能教学的重视程度,创新了教学模式。同时注重人文素质教育,多渠道提高学生的综合素质。     

Evidence for effector independent and dependent representations and their differential time course of acquisition during motor sequence learning

To investigate the representation of motor sequence, we tested transfer effects in a motor sequence learning paradigm. We hypothesize that there are two sequence representations, effector independent and dependent. Further, we postulate that the effector independent representation is in visual/spatial coordinates, that the effector dependent representation is in motor coordinates, and that their time courses of acquisition during learning are different. Twelve subjects were tested in a modified 2x10 task. Subjects learned to press two keys (called a set) successively on a keypad in response to two lighted squares on a 3x3 display. The complete sequence to be learned was composed of ten such sets, called a hyperset. Training was given in the normal condition and sequence recall was assessed in the early, intermediate, and late stages in three conditions, normal, visual, and motor. In the visual condition, finger-keypad mapping was rotated 90 degrees while the keypad-display mapping was kept identical to normal. In the motor condition, the keypad-display mapping was also rotated 90 degrees, resulting in an identical finger-display mapping as in normal. Subjects formed two groups with each group using a different normal condition. One group learned the sequence in a standard keypad-hand setting and subsequently recalled the sequence using a rotated keypad-hand setting in the test conditions. The second group learned the sequence with a rotated keypad-hand setting and subsequently recalled the sequence with a standard keypad-hand setting in the test conditions. Response time (RT) and sequencing errors during recall were recorded. Although subjects committed more sequencing errors in both testing conditions, visual and motor, as compared to the normal condition, the errors were below chance level. Sequencing errors did not differ significantly between visual and motor conditions. Further, the sequence recall accuracy was over 70% even by the early stage when the subjects performed the sequence for the first time with the altered conditions, visual and motor. There were parallel improvements thereafter in all the conditions. These results of positive transfer of sequence knowledge across conditions that use dissimilar finger movements point to an effector independent sequence representation, possibly in visual/spatial coordinates. Initially the RTs were similar in the visual and the motor conditions, but with training RTs in the motor condition became significantly shorter than in the visual condition, as revealed by significant interaction for the testing stage and condition term in the repeated measures ANOVA. Moreover, using RTs for single key pressing in the three conditions as baseline indices, it was again observed that RTs in the visual and motor conditions were not significantly different in the early stage, but motor RTs became significantly shorter by the late testing stage. These results support the hypothesis that the motor condition benefits more than the visual because it uses identical effector movements to the normal condition. Further, these results argue for the existence of effector dependent sequence representation, in motor coordinates, which is acquired relatively slowly. The difference in the time course of learning of these two representations may account for the differential involvement of brain areas in early and late learning phases found in lesion and imaging studies.     

16例交锁髓内钉＋植骨治疗胫骨骨折不愈合的疗效观察

目的 :观察交锁髓内钉 植骨治疗胫骨骨折不愈合的临床疗效。方法 :本组胫骨骨折不愈合 16例 ,男 11例 ,女 5例 :年龄 19— 76岁 ,平均 34岁 ,全部采用开放置入交锁髓内钉 植骨治疗。结果 :经 11到 2 4个月 (平均 16 .5个月 )随访 ,15例胫骨骨不连愈合。结论 :交锁髓内钉 植骨治疗胫骨骨折不愈合具有 :1、合理的生物力学设计 ;2、抗骨折旋转及短缩功能 :3、对局部血运破坏小 ;4、植骨的成骨作用等促进骨愈合 ,值得推荐使用     

Interlimb transfer of motor skill learning during walking: No evidence for asymmetric transfer

Several studies have shown that learning a motor skill in one limb can transfer to the opposite limb—a phenomenon called as interlimb transfer. The transfer of motor skills between limbs, however, has shown to be asymmetric, where one side benefits to a greater extent than the other. While this phenomenon has been well-documented in the upper-extremity, evidence for interlimb transfer in the lower-extremity is limited and mixed. This study investigated the extent of interlimb transfer during walking, and tested whether this transfer was asymmetric using a foot trajectory-tracking paradigm that has been specifically used for gait rehabilitation. The paradigm involved learning a new gait pattern which required greater hip and knee flexion during the swing phase of the gait while walking on a treadmill. Twenty young adults were randomized into two equal groups, where one group (right-to-left: RL) practiced the task initially with the dominant right leg and the other group (left-to-right: LR) practiced the task initially with their non-dominant left leg. After training, both groups practiced the task with their opposite leg to test the transfer effects. The changes in tracking error on each leg were computed to quantify learning and transfer effects. The results indicated that practice with one leg improved the motor performance of the other leg; however, the amount of transfer was similar across groups, indicating that there was no asymmetry in transfer. This finding is contradictory to most upper-extremity studies (where asymmetric transfer has been reported) and points out that both differences in neural processes and types of tasks may mediate interlimb transfer.     

Supporting skill acquisition in cochlear implant surgery through virtual reality simulation

Objectives: To evaluate the effectiveness of a virtual reality (VR) temporal bone simulator in training cochlear implant surgery.

Methods: We compared the performance of 12 otolaryngology registrars conducting simulated cochlear implant surgery before (pre-test) and after (post-tests) receiving training on a VR temporal bone surgery simulator with automated performance feedback. The post-test tasks were two temporal bones, one that was a mirror image of the temporal bone used as a pre-test and the other, a novel temporal bone. Participant performances were assessed by an otologist with a validated cochlear implant competency assessment tool. Structural damage was derived from an automatically generated simulator metric and compared between time points.

Results: Wilcoxon signed-rank test showed that there was a significant improvement with a large effect size in the total performance scores between the pre-test (PT) and both the first and second post-tests (PT1, PT2) (PT-PT1: P?=?0.007, r?=?0.78, PT-PT2: P?=?0.005, r?=?0.82).

Conclusion: The results of the study indicate that VR simulation with automated guidance can effectively be used to train surgeons in training complex temporal bone surgeries such as cochlear implantation.     

Improving With Practice: A Neural Model of Mathematical Development

The ability to improve in speed and accuracy as a result of repeating some task is an important hallmark of intelligent biological systems. Although gradual behavioral improvements from practice have been modeled in spiking neural networks, few such models have attempted to explain cognitive development of a task as complex as addition. In this work, we model the progression from a counting-based strategy for addition to a recall-based strategy. The model consists of two networks working in parallel: a slower basal ganglia loop and a faster cortical network. The slow network methodically computes the count from one digit given another, corresponding to the addition of two digits, whereas the fast network gradually “memorizes” the output from the slow network. The faster network eventually learns how to add the same digits that initially drove the behavior of the slower network. Performance of this model is demonstrated by simulating a fully spiking neural network that includes basal ganglia, thalamus, and various cortical areas. Consequently, the model incorporates various neuroanatomical data, in terms of brain areas used for calculation and makes psychologically testable predictions related to frequency of rehearsal. Furthermore, the model replicates developmental progression through addition strategies in terms of reaction times and accuracy, and naturally explains observed symptoms of dyscalculia.