人类大脑皮层对人物肖像和风景识别的fMRI研究

Continuous representation of human portrait and scene in the human cortex by fMRI

目的 探讨人类大脑对物体的识别功能区集中在大脑皮层的位置。方法 使用了三种黑白图片 :人物肖像、自然风景和打乱的图片给 9例均为右利手的正常人观看 ,同时用 1.5TMRI仪采集实验对象的解剖像、三维全脑结构像和功能像。实验结果用功能神经成像分析软件 (AFNI)进行数据处理及分析。结果 在腹侧颞叶 (梭状回 )后部存在两个相邻的区域分别对风景和人物敏感 ,其中靠内侧的区域对风景刺激的反应更强烈 ,靠外侧的区域则对人物刺激的反应更强 ;而且风景相关区域和人物相关区域呈现出从内侧到外侧的一种渐变过渡的分布。结论 尽管参与人物视觉加工的脑区和参与风景视觉加工的脑区对不同的两种刺激的反应强度有所不同 ,但两个脑区并不截然分开 ,而是连续分布并相互重叠的。

Objective To explore the main location in brain which identify the human portrait and nature scenes.Methods Nine subjects were scanned on a 1.5 T MRI scanner with GRE-EPI pulse sequence while they were presented with 3 types of black-white photographs:natural scenery,portrait,and scrambled nonsense picture.A multiple linear regression was used to identify brain regions responding preferentially to each type of stimulus and common regions for both natural scenery and portrait.The relative contributions of each type of stimulus to brain activation in these regions were then tested by using general linear test by AFNI software.Results Multiple linear regression analysis revealed two distinct but adjacent regions in both sides of the ventral temporal cortex.Although both regions showed significant activation during both types of stimuli,the medial one more preferentially responded to natural scenery,whereas the lateral one more preferentially responded to human portrait.The general linear test further revealed a gradient distribution in that a shift from portrait-related to scene-related activation was observed from lateral to medial.Conclusion These results suggest that the boundary between portrait-associated and scene-associated area is not as clear as previously demonstrated and that the representation of face and scene in the ventral temporal cortex appears to be continuous and overlapped.