The dorsomedial frontal cortex of the macaca monkey: fixation and saccade-related activity

Summary The activity of 249 neurons in the dorsomedial frontal cortex was studied in two macaque monkeys. The animals were trained to release a bar when a visual stimulus changed color in order to receive reward. An acoustic cue signaled the start of a series of trials to the animal, which was then free to begin each trial at will. The monkeys tended to fixate the visual stimuli and to make saccades when the stimuli moved. The monkeys were neither rewarded for making proper eye movements nor punished for making extraneous ones. We found neurons whose discharge was related to various movements including those of the eye, neck, and arm. In this report, we describe the properties of neurons that showed activity related to visual fixation and saccadic eye movement. Fixation neurons discharged during active fixation with the eye in a given position in the orbit, but did not discharge when the eye occupied the same orbital positions during nonactive fixation. These neurons showed neither a classic nor a complex visual receptive field, nor a foveal receptive visual field. Electrical stimulation at the site of the fixation neurons often drove the eye to the orbital position associated with maximal activity of the cell. Several different kinds of neurons were found to discharge before saccades: 1) checking-saccade neurons, which discharged when the monkeys made self-generated saccades to extinguish LED's; 2) novelty-detection saccade neurons, which discharged before the first saccade made to a new visual target but whose activity waned with successive presentations of the same target. These results suggest that the dorsomedial frontal cortex is involved in attentive fixation. We hypothesize that the fixation neurons may be involved in codifying the saccade toward a target. We propose that their involvement in arm-eye-head motor-planning rests primarily in targeting the goal of the movement. The fact that saccaderelated neurons discharge when the saccades are self initiated, implies that this area of the cortex may share the control of voluntary saccades with the frontal eye fields and that the activation is involved in intentional motor processes.     

Visual responses with and without fixation: neurons in premotor cortex encode spatial locations independently of eye position

 The ventral premotor cortex (PMv) of the macaque monkey contains neurons that respond both to visual and to tactile stimuli. For almost all of these “bimodal” cells, the visual receptive field is anchored to the tactile receptive field on the head or the arms, and remains stationary when the eyes fixate different locations. This study compared the responses of bimodal PMv neurons to a visual stimulus when the monkey was required to fixate a spot of light and when no fixation was required. Even when the monkey was not fixating and the eyes were moving, the visual receptive fields remained in the same location, near the associated tactile receptive field. For many of the neurons, the response to the visual stimulus was significantly larger when the monkey was not performing the fixation task. In control tests, the presence or absence of the fixation spot itself had little or no effect on the response to the visual stimulus. These results show that even when the monkey’s eye position is continuously changing, the neurons in PMv have visual receptive fields that are stable and fixed to the relevant body part. The reduction in response during fixation may reflect a shift of attention from the visual stimulus to the demands of the fixation task. Received: 8 April 1997 / Accepted: 16 July 1997     

Voluntary smooth eye movements with foveally stabilized targets

Summary We investigated the capacity of 6 humans to make voluntary smooth eye movements with a horizontally stabilized foveal point target. When the target was viewed on a dark field, all subjects were able to make smooth oscillatory eye movements when they attempted to imitate their own normal pursuit of sinusoidal target movement (0.2–0.7 Hz) directly preceding the stabilization on the fovea. The frequency of the imitating eye movement was in general lower than the frequency of normal pursuit by 2–35%. While fixating a foveally stabilized point target superimposed on a large, sinusoidally moving non-stabilized background, all subjects were able to make either no eye movements, eye movements nearly in phase with or eye movements nearly in counterphase with the background movement depending on the instruction to imagine the target as head-stationary, moving in phase, or moving in counterphase with the background. The accuracy of the frequency of the smooth eye movement with the stabilized target on the moving background was higher than during imitation of pursuit on the dark field but the precision of the frequency was lower than during normal pursuit. When the background moved pseudo-randomly all subjects could voluntarily inhibit their smooth eye movements or could make smooth eye movements in phase with the background. Only 2 subjects showed a limited ability to make smooth eye movements opposite to the pseudo-random background movement. The results suggest that with predictable background movement the volition of the subject rather than the movement of the background determines the eye movements when the subject looks at the foveally stabilized target.     

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     

顺行交锁髓内钉治疗肱骨骨折

目的探讨顺行交锁髓内钉治疗肱骨骨折的手术要点和治疗效果。方法回顾性分析2003年10月～2005年10月23例顺行肱骨交锁髓内钉治疗肱骨干中上段骨折。结果全部病例随访6个月～1年3个月,平均11个月。所有病例均骨性愈合,平均临床愈合时间为2.4个月。所有关节活动度均可。结论顺行交锁髓内钉治疗肱骨中段或中上段骨折,效果良好。     

腰椎斜外侧椎间融合术后融合器沉降的原因分析

目的:观察斜外侧椎间融合(oblique lateral interbody fusion,OLIF)治疗腰椎病变术后融合器沉降现象,总结融合器沉降特点,并分析其原因,提出预防性措施。方法:回顾性分析2015年10月至2018年12月收治的144例腰椎病变资料,其中男43例,女101例;年龄20~81(60.90±10.06)岁;腰椎间盘退行性病变17例,巨大型腰椎间盘突出12例,椎间盘源性腰痛5例,腰椎管狭窄症33例,腰椎退行性滑脱26例,腰椎椎弓峡部裂伴椎体滑脱28例,腰椎内固定术后邻椎病11例,炎症转归期原发性椎间隙炎7例,腰椎退行性侧后凸5例。术前双能X线骨密度检查提示存在骨量减少或骨质疏松57例,骨密度正常87例。融合节段数:单节段124例,2节段11例,3节段8例,4节段1例。采用Stand-alone OLIF 40例,OLIF联合后路椎弓根螺钉固定104例。记录术后融合器沉降的发生情况,对可能风险因素进行单因素分析,观察融合器沉降对于临床结果的影响。结果:所有手术顺利完成,手术时间中位数99 min,术中出血量中位数106 ml;术中发生终板损伤30例,合并椎体骨折5例。所有患者获得随访,时间6~30(14.57±7.14)个月。随访过程中除原发性腰椎间隙炎病例、部分腰椎椎弓峡部裂伴椎体滑脱病例,其余出现不同程度的融合器沉降现象,其中正常沉降119例,异常沉降25例(Ⅰ级23例,Ⅱ级2例)。未出现椎弓根螺钉系统松动或断裂现象,椎间隙高度由术前的(9.48±1.84) mm恢复至术后3~5 d的(12.65±2.03) mm及末次随访时的 (10.51±1.81) mm,术后3~5 d与术前比较、末次随访与术后3~5 d比较差异均有统计学意义(P<0.05)。椎间融合率为94.4%(136/144)。腰痛和腿痛视觉模拟评分(visual analogue scale,VAS)分别由术前的(6.55±2.29)、(4.72±1.49)分降低至末次随访时的(1.40±0.82)、(0.60±0.03)分(P<0.000 1);ODI由术前的(38.50±6.98)%恢复至末次随访时的(11.30±3.27)%(P<0.05)。并发症发生率为31.3%(45/144),再手术率9.72%(14/144),其中因融合器沉降或移位而再次手术8例,占再手术的57.14%(8/14)。单因素分析结果显示:在骨量减少或骨质疏松组、Stand-alone OLIF组、2节段或以上融合组、终板损伤组中其异常沉降例数分别高于骨量正常组、OLIF联合椎弓根螺钉固定组、单节段融合组、终板无损伤组。结论:融合器沉降是OLIF术后较为常见的现象,术前骨量减少或骨质疏松、Stand-alone OLIF应用、2节段或以上融合和术中终板损伤可能是术后融合器沉降的重要因素。虽然融合器沉降程度与临床症状无明显相关,但存在融合器移位的风险,需要加强预防,以降低因融合器沉降而带来的严重并发症,包括再手术。     

对99例髋臼骨折内固定治疗的分析

从1972年11月到1994年3月,401例髋臼骨折病人中的99例经手术治疗并获随访,包括30例双柱骨折,13例横骨折伴后壁骨折,9例后壁骨折,9例后柱骨折,9例前往骨折伴前壁骨折,13例T形骨折和16例横骨折.平均随访时间为7年(2～14).外科手术入路的选择,后入路53次,髂腹股沟入路23次,延长的髂股骨入路11次,放射状入路9次和结合性入路6次.复位情况用X线平片来评判,解剖复位的有59例(59.6%),接近解剖复位(<2mm的错位)的有19例(19.2%).总结果用Harris Hip Score来评判,优秀的有53例(53.5%),良好的有25例(25.3%),一般的有14例(14.1%),差的有7例(7%).并发症中,有10例(53%)为感染,7例(37%)为静脉栓塞.这些结果表明,对于错位严重的髋臼骨折,切开复位内固定是一种可以选择的治疗方法.     

What is normal binocular vision?

The vergence position of the eyes is determined by the near fixation-accommodationmiosis synkinesis and the fusion mechanism. The contribution of both systems was analysed in 30 normal subjects and 16 subjects with abnormal binocular vision. Prism fixation disparity curves were determined in three different experimental situations: the routine method according to Ogle, a method to stimulate the synkinetic convergence (Experiment I, with one fixation point as sole binocular stimulus) and a method to stimulate the fusion mechanism (Experiment II, with random dot stereograms). Experiment I produced flat curves and Experiment II steep curves. The mean diameter of the horizontal Panum area was 5 minutes of arc in Experiment I and 2 in Experiment II. On the basis of these findings, it was postulated that the synkinetic system operates in the absence of fixation disparity and the fusion system in the presence of fixation disparity. In Experiment II, esodisparities of 100 minutes of arc occur in a number of normal subjects.The dividing line between normal and abnormal binocular vision therefore is blurred. Normal persons can display disparities, the order of magnitude of which is equal to that of the angle of squint in micro-strabismus.     

胸骨上举术的固定方式与结果

目的：分析胸骨上举术的不同固定方式与手术效果的关系。方法：１４８例经胸骨上举术治疗的漏斗胸患儿，术中分别用自制金属支杠、三点式悬吊和塑料及金属制成的支架背心悬吊固定胸骨。结果：其中８４例患儿获术后６个月至６年（平均２年）随访观察，绝大部分效果满意，仅２例复发。２７例保留金属支杠于术后１０～１２个月拔除者，无复发，外观更满意。结论：胸骨上举术治疗漏斗胸的效果肯定，手术安全。用自制金属支杠固定上举的胸骨操作简便，术后护理方便。保持金属支杠于手术后１０～１２个月才拔除，有利于防止复发，胸廓外形更满意。三点式悬吊固定对较小的轻度患儿适用。支架背心悬吊固定法术后护理不便，影响患儿日常生活，使用受限     

病灶清除一期前路植骨钛板内固定治疗胸腰椎结核

目的　探讨胸腰椎结核病灶清除,一期前路植骨钛板内固定的手术方法与疗效。方法　对1997年5月~2003年6月收治的23例胸腰椎结核患者,术前常规应用异烟肼、链霉素、利福平和乙胺丁醇四联抗痨治疗最少3周,并纠正贫血及低蛋白血症。血沉恢复正常或连续观察低于50mm/h后进行手术。采取病灶清除、一期前路植骨、“K”形钛板内固定。术后继续抗痨治疗10-12个月。结果　手术时间2-3 5h,平均2 6h。输血400~1200ml,平均600ml。伤口一期愈合,随访时间18 -61个月,植骨融合时间为4~9个月,平均6个月。5例截瘫患者均恢复,术后脊柱后凸角度平均矫正19°。结论　采取病灶清除、一期前路植骨钛板内固定治疗胸腰椎结核,具有矫正后凸畸形,稳定脊柱,并发症少,术后早期离床活动的优点。是较安全有效的治疗方法。