线索提示对忽视症患者线等分反转效应的影响

目的 研究线段长度、线索提示对忽视症患者线等分试验中反转效应的影响,以探讨注意、感觉、数量估计障碍等是否参与忽视症患者线等分试验中反转效应的神经机制.方法 试验对象为15例左侧空问忽视症患者和15名年龄、文化程度、MMSE评分等相匹配的健康人,进行不同线段长度和线索提示的线等分试验,观察线等分试验的偏移率和反转效应.健康对照组间分析比较用两独立样本t检验,各组内结果分析采用多因素的方差分析.结果 忽视症患者在单纯水平线等分中当线段长度分别为4、6、8、10、12 cm时,其偏移百分率(%)分别为-5.71±5.13、-2.48±8.83、-1.18±10.90、0.43±8.12、2.17±7.04,线段长度对偏移率影响有统计学意义(F=12.5,P＜0.01).线段长度小于10 cm时,9例表现为反转效应.相应长度线段右、左侧单侧增加线索提示,可削弱和增强忽视症患者线等分试验的反转效应[偏移百分率(%)分别为-3.93±7.04、2.43±6.34、4.93±5.19、6.49±3.36、6.38±4.18,P＜0.01;-10.93±8.85、-7.95±8.44、-4.14±8.37、-2.60±9.96、-1.57±10.67,P=0.03];双侧增加线索提示对反转效应影响无统计学意义[偏移百分率(%)分别为-5.93±7.76、-0.52±8.20、0.54±6.34、2.57±5.02、2.79±3.92,P=0.35].改变线索提示高度对反转效应影响无统计学意义(F=1.94,P=0.14).结论 在线等分试验中当线段长度较短时主观中点向左偏移,表现为反转效应,表明数量估计障碍参与反转效应的形成.在线等分试验中增加单侧线索提示对偏移率影响显著,表明注意导向参与反转效应的形成.改变线索提示高度对反转效应影响无统计学意义,表明感觉障碍在反转效应形成过程中不起独立因素.

Effects of cueing on crossover effect in line bisection in hemispatial neglect

Objective To investigate the relationship of attentional orientation,sensory disorder or magnitude estimation with cross-over effect in the line bisection of hemispatial neglect patients and to evaluate the influences of the length of lines and cueing on the performance of line bisection of neglect patients.Methods Fifteen patients with hemispatial neglect and 15 age and education-level-matched healthy controls underwent line bisection experiment.in which difierent types of cues and difierent length of bisected lines were given to observe their effects on the deviation.Analyses of variance (ANOVAs)were used to analyze the data in each group.Results When the lengths of lines were 4,6,8,10,12 cm,percentages of line bisection deviation(%)without cue were-5.71±5.13,-2.48±8.83,-1.18±10.90.0.43±8.12,2.17±7.04 respectively.The experiment showed that deviation was related to the length of lines ( F=12.5,P＜0.01).Nine patients exhibited cross-over effect when the lines were shorter than 10 cm.Another interesting result was that ipsilesional cues led to a reduction in bisection errors ( percentages of line bisection deviation(%)were-3.93±7.04,2.43±6.34,4.93±5.19,6.49±3.36,6.38±4.18,P＜0.01),however,contralesional ones resulted in a reverse effect(percentages of bisection deviation(%)were-10.93±8.85,-7.95±8.44,-4.14±8.37,-2.60±9.96,-1.57±10.67,P=0.03).As for bilateral cues,both cueing had no influence on line bisection(percentages of bisection deviation(%)were -5.93±7.76,-0.52±8.20,0.54±6.34.2.57±5.02,2.79±3.92,P=0.35).The length of cues had no influence on line bisection(F=1.94.P=0.1 4).Condusions The subjective midpoint excurses toward left when the length of line is relatively short.which is referred as crossover effect.indicating magnitude estimation a factor of crossover effect.Unilateral cues affects the performance of line dissection of neglect patients.which may be accounted for attentional orientational biases.No effect of the cue length suggested sensory disorder does not play a role in the crossover effect.