Understanding neural system dynamics through task modulation and measurement of functional MRI amplitude, latency, and width
Understanding neural system dynamics through task modulation and measurement of functional MRI amplitude, latency, and width
复制标题
DOI：
10.1073/pnas.0337747100
复制
发表时间：
2003-02-04
影响因子：
11.1
通讯作者：
Bandettini, PA
中科院分区：
文献类型：
--
作者：
Bellgowan, PSF;Saad, ZS;Bandettini, PA
结合血流动力学幅度、延迟和宽度的估计来研究词汇决策中涉及的系统动力学。受试者使用旋转 0 度、60 度或 120 度的单词和非单词刺激来执行词汇决策任务。对重复刺激的平均血流动力学反应适合与不同起始时间和持续时间的重边函数卷积的伽玛变量函数，以估计每个体素的激活延迟和宽度。与旋转刺激和非单词的反应时间延长相一致，运动皮层在这两种情况下都显示出延迟的血流动力学起始。语言区域，如舌回、颞中回、梭状回和楔前叶，都表现出对旋转刺激的血流动力学起始延迟，但对非单词刺激则不然。额下回显示出旋转刺激的起始潜伏期增加和对非单词的更广泛的血流动力学反应，这与词汇决策任务期间该区域的长时间处理一致。语音处理区域（例如颞上回和角回）显示旋转刺激没有延迟或宽度差异。这些结果表明，无论刺激方向如何，通往词典的语音路线（而不是语义路线）都可以继续进行。这项研究证明了除了振幅之外估计血流动力学延迟和宽度的实用性，可以对大脑功能进行更定量的测量，例如心理计时。
Estimates of hemodynamic amplitude, delay, and width were combined to investigate system dynamics involved in lexical decision making. Subjects performed a lexical decision task using word and nonword stimuli rotated 0degrees, 60degrees, or 120degrees. Averaged hemodynamic responses to repeated stimulation were fit to a Gamma-variate function convolved with a heavyside function of varying onset and duration to estimate each voxel's activation delay and width. Consistent with prolonged reaction times for the rotated stimuli and nonwords, the motor cortex showed delayed hemodynamic onset for both conditions. Language areas such as the lingual gyrus, middle temporal gyrus, fusiform gyrus, and precuneus all showed delayed hemodynamic onsets to rotated stimuli but not to nonword stimuli. The inferior frontal gyrus showed both increased onset latency for rotated stimuli and a wider hemodynamic response to nonwords, consistent with prolonged processing in this area during the lexical decision task. Phonological processing areas such as superior temporal and angular gyrus showed no delay or width difference for rotated stimuli. These results suggest that phonological routes but not semantic routes to the lexicon can proceed regardless of stimulus orientation. This study demonstrates the utility of estimating hemodynamic delay and width in addition to amplitude allowing for more quantitative measures of brain function such as mental chronometry.