| Objectives(1)To explore the effects of spatial range and cognitive load on the visual attention function in right hemisphere stroke patients;(2)To explore the effects of cognitive load on the spatial working memory function in right hemisphere stroke patients.Methods A toatal of 28 right hemisphere stroke patients were recruited,including 7 with left spatial neglect(n+ group)and 21 without left neglect(n-group).Another 13 healthy individuals served as control group.In this study,visual search paradigm was applied to examine the visual attention capacity and spatial working memory using 4 trials,that is,visual search trails with patterns,visual search trials with Chinese characters,spatial working memory trials with patterns,and spatial working memory with Chinese characters.During each trial,patterns and Chinese characters were used as stimuli with various number(4/8/16,manipulating different cognitive loads)in various size of pictures(large/medium/small,manipulating different spatial ranges).Visual search trials were conducted to obtain the bias rate and reaction time(RT),whereas accuracy and RT were obtained during spatial working memory trials.Results(1)With regard to visual search trails of spatial range,patients with neglect exhibited significantly higher bias rate in either patterns [large/medium/small:(0.16±0.06)/(0.23±0.06)/(0.13±0.03)] or Chinese characters [large/medium/small:(0.23±0.07)/(0.26±0.06)/(0.17±0.05)] with various picture size than that in patients without neglect [large/medium/small pictures(pattern stimuli):(0.02±0.01)/(0.06±0.02)/(0.05±0.01);large picture/medium picture/small picture(character stimuli):(0.00±0.01)/(0.08±0.02)/(0.00±0.02)] and healthy controls,respectively.(2)With regard to visual search trails of cognitive load,patients with neglect exhibited significantly higher bias rate in either patterns [4/8/16:(0.18±0.06)/(0.11±0.05)/(0.220±0.09)] or Chinese characters [4/8/16:(0.27±0.08)/(0.21±0.05)/(0.19±0.07)] with various item numbers than that in patients without neglect [4/8/16 patterns:(0.00±0.01)/(0.03±0.02)/(0.09±0.02);4/8/16 Chinese characters:(0.01±0.01)/(0.03±0.02)/(0.05±0.03)] and healthy controls,respectively.(3)With regard to visual search trails of spatial range or cognitive load,patients without neglect exhibited higher attention bias rate in large/small pictures [(0.02±0.01)/(0.05±0.01)] containing pattern stimuli or with 16 items [16 patterns/16 Chinese characters:(0.09±0.02)/(0.05±0.03)] than that in healthy controls [large/small patterns:(-0.05±0.01)/(-0.05±0.04);16 patterns /16 Chinese characters:(-0.01±0.01)/(-0.03±0.01)].(4)With regard to visual search trails of cognitive load of 16,patients without neglect had significantly longer RTs in the left visual field [16 patterns/Chinese characters on the left side:(1874±95)ms/(1914±92)ms)] than the right side [(16 patterns/Chinese characters on the right side:(1481±91)ms/(1620±93)ms].In addition,in the left visual field,patients without neglect had slower RTs than their healthy counterparts.(5)With regard to working memory trails of cognitive load,patients with neglect had significantly lower accuracy than healthy controls in full visual field,especially the left visual field [4/8/16 patterns on the left side:(59.26±3.70)%/(62.96±7.41)%/(48.15±25.93)%;4/8/16 Chinese characters on the left side:(44.44±27.96)%/(37.04±9.80)%/(14.82±7.41)%].As for patterns,patients without neglect had lower accuracy than healthy controls.Besides,patients with neglect had significantly lower accuracy in the left visual field than the right side [4/8/16 patterns on the right side:(100.00±0.00)%/(85.19±7.41)%/(77.78±11.11)%;4/8/16 Chinese characters on the right side:(92.59±3.70)%/(81.48±7.41)%/(62.96±3.70)%],indicating considerable left neglect.(6)With regard to working memory trails of patterns,patients without neglect had significantly longer RTs [4/8/16 patterns on the left side:(1836±153)ms/(1928±116)ms/(2071±181)ms;4/8/16 patterns on the right side:(1786±125)ms/(1918±167)ms/(2034±190)ms] than healthy controls [4/8/16 patterns on the left side:(1260±107)ms/(1285±88)ms/(1471±117)ms;4/8/16 pattens on the right side:(1324±97)ms/(1349±105)/(1393±122)ms] in full visual field,respectively.In working memory trails of Chinese characters,patients without neglect had higher RTs [4/8/16 Chinese characters on the left side:(1664±186)ms/(1702±214)ms/(1979±178)ms] in the left visual field than healthy controls [4/8/16 Chinese characters on the left side:(1248±114)ms/(1253±111)ms/(1368±104)ms];In the right visual field,patients without neglect had longer RTs [16 Chinese characters on the right side:(1850±187)ms] than healthy controls [16 Chinese characters on the right side:(1317±119)ms] only when characters were of large numbers.Conclusions(1)Patients either with or without neglect exhibited a certain degree of right attention bias for different spatial range or cognitive load;(2)RTs of attention process in patients without neglect were affected by items number,particularly in the left visual field.Such changing trend was more sensitive when pattern materials were presented;(3)Patients either with or without neglect had lower efficiency in the process of spatial working memory,especially in the left visual field,which presented a lateralized feature;(4)Patients without neglect exhibited higher RTs in the process of spatial working memory,particularly when pattern materials were presented.However,no lateralized results were observed. |
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