수십분의 일초 시간의 시각변별 과제에서 원숭이 일차시각피질의 신경 활동

학위논문 (박사)-- 서울대학교 대학원 : 협동과정 인지과학전공, 2017. 2. 이춘길.Timing is a fundamental process to represent and discriminate events such as visual motion. However, little is known about precise mechanisms of how tens-of-milliseconds interval, critical for perceiving visual motion (Burt and Sperling 1981), is timed in the mammalian brain (Mauk and Buonomano 2004). Here we show that the neurons of rhesus primary visual cortex (V1) are sensitive to the temporal interval of tens-of-milliseconds between two stationary visual stimuli that sequentially appeared, the first outside the classical receptive field and the second within the center of receptive field. We further show that while monkeys discriminated the temporal interval, V1 neurons showed two other activity components: one that varied with upcoming choice between interval alternatives with a choice probability that was as strong as reported for orientation discrimination (Nienborg and Cumming 2014), and another activity component in the form of LFP that was related to reward. These results indicate that V1 neurons are sensitive to tens-of-milliseconds interval and modulate their activity according to perceptual decision on temporal interval regardless of physical interval. These results suggest a new role of the center-surround interaction for interval timing and discrimination.1. Introduction 1 1.1. Purpose of the study 4 2. Method 5 2.1. Animal preparation 5 2.1.1. Subject 5 2.1.2. Subject training 5 2.1.3. Dura cleaning 6 2.2. Experimental setups 6 2.2.1. Stimulus generation 6 2.2.2. Eye monitoring 8 2.2.3. Neural recording 9 2.3. Experimental procedure 11 2.3.1. Experimental paradigm 11 2.3.2. Receptive field mapping 15 2.4. Data Analysis 17 2.4.1. Spike extraction 17 2.4.2. Spike sorting 18 2.4.3. Spike density function 20 2.4.4. Validation of data 20 2.4.5. Spectrogram 21 2.4.6. Distance Index 21 2.4.7. Test of eye stability 23 2.4.8. Detection of microsaccades 24 2.4.9. Choice-related activity component period 26 2.4.10. Choice probability 27 3. Results 28 3.1. Data summary 28 3.2. Behavioral performance in visual discrimination 28 3.3. Interval-related spike activity component 30 3.3.1. Example cell activity 30 3.3.2. Population summary 32 3.3.3. Pattern of interval-related activity component 35 3.4. Example of invalid cell 36 3.5. Choice-related activity component 38 3.5.1. Example cell activity 38 3.5.2. Population summary 41 3.5.3. Period of choice-related activity component 42 3.5.4. Absence of choice-related activity component in late period 44 3.5.5. Relation between during early and late periods 46 3.5.6. Choice probability 47 3.6. Grand mean of population spike activity 49 3.7. Interval-related activity component and discrimination 50 3.7.1. Error trials interval-related activity component 50 3.7.2. Distance index in error trials 52 3.7.3. Linear discriminant analysis 53 3.8. Noise correlation 55 3.9. LFP response 56 3.9.1. LFP response of example site 56 3.9.2. Population LFP and spike activity 58 3.9.3. Choice-related LFP response 58 3.9.4. Choice-related LFP spectrogram 59 3.10. Reward-related activity component 61 3.10.1. Reward period 61 3.10.1.1. Saccade onset aligned LFP 61 3.10.1.2. LFP response by saccadic direction 63 3.10.1.3. Extraction of reward-related activity component 66 3.10.1.4. Subthreshold LFP of reward-related activity component 67 3.10.1.5. Control of solenoid valve sound 70 3.10.2. Potential effects of reward on next trial (1) 73 3.10.2.1. LFP response in fixation period 73 3.10.2.2. Spontaneous spike response in fixation period 76 3.10.3. Potential effects of reward on next trial (2) 79 3.10.4. Behavior depending on reward history 83 4. Discussion 86 4.1. Interval timing based on surround interaction 86 4.2. Choice related signal and its correlation with sensory response 89 4.3. Reward related neural activity component in V1 90 4.4. Relation to motion processing 91 References 94 Abstract in Korean 105Docto

Is There Relationship between Brain Atrophy and Higher Incidence of Hip Fracture in Old Age? -A Preliminary Study-

PURPOSE: The studies on the correlation between incidence of fall and brain atrophy have been going on to find out the cause of fall and its prevention. The purpose of this study was to explore the relationship between incidence of hip fracture and brain volume, measured by magnetic resonance image. MATERIALS AND METHODS: A total of 14 subjects with similar conditions (age, height, weight, and past history) were selected for this study. Fracture group (FG) was consisted of 5 subjects with intertrochanteric fracture. Control group (CG) had 9 subjects without intertrochanteric fracture. MRI-based brain volumetry was done in FG and CG with imaging software. Total brain (tBV), absolute cerebellar volumes (aCV) and relative cerebellar volumes (rCV) were compared between two groups. Student t-test was used to statistically analyze the results. RESULTS: In FG, average tBV, aCV and rCV were 1034.676±38.80, 108.648±76.80 and 10.50±0.72 cm³, respectively. In CG, average tBV, aCV and rCV were found to be 1106.459±89.15, 114.899±98.06 and 10.39±0.53 cm³, respectively, having no statistically significant difference (p>0.05). CONCLUSION: There was no significant difference between the fracture and control groups. Patients with neurologic disease such as cerebellar ataxia definitely have high incidence of fall that causes fractures and have brain changes as well. However, FG without neurologic disease did not have brain volume change. We consider that high risk of fall with hip fracture might decrease brain function which is not obvious to pickup on MRI.ope

A Rare Case of Aggravated Hypercalcemia of Malignancy After Surgery

Paraneoplastic syndromes are caused by ectopic hormone production in malignant tumors. Hypercalcemia of malignancy is the main manifestation of paraneoplastic syndromes and can lead to acute kidney injury, life-threatening arrhythmia, and cardiac arrest. Here, we present a 70-year-old Asian female with a probable diagnosis of advanced lung cancer with hypercalcemia of malignancy. She underwent surgery to treat a pathologic fracture of the humerus. In this case, hypercalcemia of malignancy was unexpectedly aggravated after surgery, and hypercalcemic complications led to a poor outcome for the patient.ope

Incomplete footprint coverage under tension in repair of isolated supraspinatus full-thickness tear

Although it is well known that repairing large or massive tears under tension may have an adverse effect on healing of the repaired tendons, only few studies have addressed this issue in medium-sized isolated supraspinatus full-thickness tear. The purpose of this study was to compare the clinical outcomes and structural integrity of arthroscopic rotator cuff repair with tension versus without it. This study retrospectively investigated 90 patients who underwent arthroscopic repair in a single-row for medium-sized isolated supraspinatus full-thickness tear. The patients were assigned to either repaired under tension (Group A, n = 38) or repaired without tension (Group B, n = 52) groups. Functional outcomes were assessed using the patient reported subjective values and the active range of motion (ROM). Postoperative radiographic evaluation was performed 6 months after the surgery to assess the structural integrity of the repaired tendons. Changes in the subjective shoulder scores from initial to 2 years after surgery showed no statistical significance between the two groups. The ROMs measured at initial and 2 years after surgery also showed no statistical difference between the two groups. Postoperative radiological evaluations found a significantly higher re-tear rate in Group A (28.9%, 11/38) than in Group B (9.6%, 5/52). The torn cuff tendons that were repaired under tension as retraction with limited mobility had significantly higher re-tear rate despite having immobilized for 6 weeks after surgery, but their clinical outcomes showed no significant difference from the outcomes of repaired tendons without tension.ope

Clinical Outcomes for Isolated Subscapularis Tears With Advanced Fatty Infiltration: Nonoperative Treatment Versus Arthroscopic Single-Row Repair

Background: No study has investigated the treatment outcomes of isolated subscapularis tears with advanced fatty infiltration and tear progression to the supraspinatus tendon. Purpose: To assess the natural progression of isolated subscapularis tears with advanced fatty infiltration and compare clinical outcomes between nonoperative and operative treatment. Study design: Cohort study; Level of evidence, 3. Methods: This study included 52 patients who received either operative (group A) or nonoperative (group B) treatment at our institution for isolated subscapularis full-thickness tears with grade 3 or 4 advanced fatty infiltration. All study patients had a minimum 2-year follow-up. The following 4 functional measures were used: visual analog scale for pain, Subjective Shoulder Value, American Shoulder and Elbow Surgeons score, and University of California Los Angeles score. The modified belly-press test was used to assess subscapularis muscle strength. In group A, structural integrity was evaluated using magnetic resonance imaging at 6 months after surgery. In addition, ultrasonographic evaluation was performed on both groups during the follow-up period to assess tear progression into the supraspinatus tendon. Results: At initial presentation, all functional assessment scores were significantly worse in group A versus group B (P ≤ .05 for all 4 scores). When we compared the mean change in scores before treatment versus after treatment, the group A patients were found to have significantly greater improvement than group B patients (P < .001 for all 4 scores); however, no significant difference was seen in final outcome scores between the groups. Although a high retear rate of 78.6% (22/28) was identified in group A, both groups showed no further tear progression to the supraspinatus tendon at the final ultrasonographic evaluation. Conclusion: For isolated subscapularis tears with advanced fatty infiltration, clinical improvement was seen with both nonoperative and operative treatment. Although the operatively treated group started with lower baseline scores, there were no significant differences in outcomes at final follow-up. Considering the high retear rate even after repair, surgical treatment of these lesions may not be warranted. Early detection and prompt repair of subscapularis tears, before the lesion becomes advanced with grade 3 or 4 fatty infiltration, are important for better outcomes.ope

원위 쇄골 골절에서 구조가 다른 금속판으로 외측 고정시 나사 직경과 뽑힘 강도의 관계: 생역학적 실험

Introduction: Plate fixation has recently gained popularity among the various surgical methods used to treat Neer type II distal clavicle fractures. The use of a low-profile distal clavicle locking plate is logically considered a better option when there is no significant difference in the fixation strength between insertions of 3.5- and 2.7-mm diameter screws. Therefore, the purpose of this biomechanical study was to investigate any differences in fixation strength among varying sizes of screws that are used to treat distal clavicle fractures. Methods: The study was performed with 20 paired shoulder girdles from 10 fresh frozen cadavers. To create a type IIA fracture of Neer classification, osteotomy was performed perpendicularly to the longitudinal axis of the clavicle at the medial end point of the conoid ligament. Two custom-made fixtures designed to be attached to both upper and lower sides of the Instron were fabricated for the evaluation Results: The mean maximum pull-out strength for fixation using 3.5-mm diameter screws was 241.9±67.8 N, whereas the mean pull-out strength in fixation with 2.7-mm diameter screws was 228.1±63.0 N. There was no statistically significant difference between the two groups. In addition, there was a significantly positive correlation between bone mineral density and pull-out strength in both Group A. Conclusion: For Neer type IIA distal clavicle fractures, distal fragment fixation with 2.7-mm diameter screws in a distal clavicle locking plate showed comparable biomechanical pull-out strength at time-zero setting as fixation with 3.5-mm diameter screws in the hook plate. Therefore, if the distal fragment of the fractured clavicle is not extremely small, fixation of a distal fragment with a low-profile plate and 2.7-mm screws may be an alternative option. 연구 배경 및 목적: Neer 분류 2형 원위 쇄골 골절의 다양한 치료 방법 중 금속판 고정술은 최근 널리 사용되고 있다. 3.5mm와 2.7mm의 나사못 가운데 직경에 따른 고정력의 차이가 없다면 2.7mm의 나사못을 사용하는 원위 쇄골 잠김 금속판을 사용하는 것이 더 좋은 선택지일 것이다. 본 연구의 목적은 생역학적 실험을 통하여 원위 쇄골 골절에서 외측 골편의 고정에 사용하는 나사못의 직경에 따른 고정력의 차이에 알아보고자 하였다. 연구 재료 및 방법: 좌우 10쌍의 신선동결사체를 대상으로 연구를 진행하였다. Neer 분류 2A형의 골절을 만들기 위하여 원추인대가 쇄골에 부착되는 가장 내측을 기준으로 수직으로 절골을 시행 후 금속판을 고정하였다. 뽑힘 강도는 자체 제작한 고정구를 인스트론 장비의 위 아래에 연결 후 카데바를 결착하여 측정하였다. 연구 결과: 최대 뽑힘 강도는 3.5mm 직경을 이용한 고정에서는 241.9±67.8 N, 2.7mm 직경을 이용한 고정에서는 228.1±63.0 N 으로 두 그룹 사이의 통계적인 차이는 관찰되지 않았다. 또한 두 그룹 모두에서 골밀도가 증가하면 뽑힘강도가 증가하는 양의 상관관계를 보였다. 결론: Neer 분류 2형 원위 쇄골 골절에서 원위 쇄골 잠김 금속판에서 사용하는 2.7mm 직경의 나사못과 Hook 금속판에서 사용하는 3.5mm 직경의 나사못의 뽑힘 강도는 차이를 보이지 않았다. 그러므로 외측 골절 골편이 매우 작은 경우를 제외한다면 2.7mm 나사못을 이용한 금속판 고정 방법이 좋은 대안이 될 수 있다.open박

Pull-out Strength of Suture Anchor and Torque of Buddy Anchor for an Osteoporotic Humeral Head in Rotator Cuff Repair: Parallel Versus Divergent Insertion

Background: The buddy anchor technique is useful to reinforce loose anchors in the osteoporotic humeral head during arthroscopic rotator cuff repair. However, theoretical parallel insertion of the buddy anchor to index a loose anchor is challenging in arthroscopy and can widen the entry site and decrease structural integrity. Purpose: To investigate and compare the biomechanical stability between 2 buddy anchor insertion techniques (parallel insertion vs divergent insertion) in the osteoporotic humeral head. Study design: Controlled laboratory study. Methods: A total of 24 paired fresh-frozen cadaveric shoulders were used, and each pair was randomly assigned to either the parallel insertion group or the divergent insertion group. In the parallel insertion group, the buddy anchor was inserted parallel to the index loose anchor. In the divergent insertion group, the buddy anchor was inserted at a 20° angle in the medial direction to the index loose anchor. The insertion torque of the buddy anchor and ultimate pull-out strength of the index anchor were measured and compared between the 2 groups. Results: The mean maximum insertion torque was significantly higher in the parallel insertion group (16.1 ± 1.8 cN·m) compared with the divergent insertion group (12.0 ± 1.5 cN·m) (P < .001). The mean ultimate pull-out strength was significantly higher with divergent insertion (192.2 ± 28.6 N) than with parallel insertion (147.7 ± 23.6 N) (P < .001). Conclusion: For application of the buddy anchor system in the cadaveric osteoporotic humeral bone model, divergent insertion showed better ultimate pull-out strength than conventional parallel insertion, despite inferior maximum insertion torque. Clinical relevance: The results of this study widen the applicability and accessibility for the buddy anchor system.restrictio

Subscapularis re-tears associated with preoperative advanced fatty infiltration and greater subscapularis involvement, leading to inferior functional outcomes and decreased acromiohumeral distance

Purpose: This study aimed to investigate the influence of repaired subscapularis integrity on midterm results for anterosuperior massive rotator cuff tears (MRCTs) treated with partial rotator cuff repair. Methods: This study included 57 patients who underwent arthroscopic partial repair for an anterosuperior MRCT. They were assigned to the healed subscapularis group (Group H 37 patients) or subscapularis re-tear group (Group R 20 patients). Preoperative and postoperative functional scores and active ranges of motion (ROMs) were assessed. Preoperative and 6-month follow-up magnetic resonance arthrography (MRA)/computed tomography arthrography (CTA) images were compared between groups. Results: At the final follow-up, mean functional shoulder scores including ROMs improved significantly in both groups compared to preoperative values (p < 0.001), except for forward flexion and internal rotation in Group R. All final functional values and ROMs (excluding external rotation) were better in Group H than in Group R (p < 0.001). Preoperative stage of fatty infiltration in the subscapularis muscle was significantly worse in Group R (p < 0.001). On follow-up MRA/CTA, the immediate residual defect after partial repair increased in 81% (30/37; mean, 17.8 mm) of patients in Group H and 100% (mean 24.6 mm) in Group R (p < 0.001). At final follow-up, mean acromiohumeral distance significantly decreased from 8.2 to 6.0 mm in Group H (p < 0.001) and from 8.3 to 4.9 mm in Group R (p < 0.001). There was a significant difference in final acromiohumeral distance between groups (p < 0.001). Conclusion: After a minimum 5-year follow-up after arthroscopic partial repair of anterosuperior MRCT, subscapularis re-tear was identified in 35% of patients (20/57) on early postoperative follow-up MRA/CTA. The subscapularis re-tear group exhibited more preoperative advanced fatty infiltration and greater extents of subscapularis involvement, which led to statistically inferior functional outcomes and decreased acromiohumeral distance at final follow-up. Nonetheless, in terms of a minimal clinically important difference, substantial clinical benefit, and patient-acceptable symptomatic state for clinical significance, there were no significant differences between the groups. Level of evidence: III.restrictio