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1.
Brain regions involved in mental rotation were determined by assessing increases in fMRI activation associated with increases in stimulus rotation during a mirror-normal parity-judgment task with letters and digits. A letter-digit category judgment task was used as a control for orientation-dependent neural processing unrelated to mental rotation per se. Compared to the category judgments, the parity judgments elicited increases in activation in both the dorsal and the ventral visual streams, as well as higher-order premotor areas, inferior frontal gyrus, and anterior insula. Only a subset of these areas, namely, the posterior part of the dorsal intraparietal sulcus, higher-order premotor regions, and the anterior insula showed increased activation as a function of stimulus orientation. Parity judgments elicited greater activation in the right than in the left ventral intraparietal sulcus, but there were no hemispheric differences in orientation-dependent activation, suggesting that neither hemisphere is dominant for mental rotation per se. Hemispheric asymmetries associated with parity-judgment tasks may reflect visuospatial processing other than mental rotation itself, which is subserved by a bilateral fronto-parietal network, rather than regions restricted to the posterior parietal.  相似文献   

2.
目的应用fMRI技术探讨中国青年和老年人群在简单运算任务下脑激活模式及其与行为学之间的关系。方法分别对青年组(19例)和老年组(20例)健康志愿者进行对照任务和简单运算任务下的fMRI检查。结果两组受试者受教育程度(P=0.125)、智力水平(P=0.921),以及完成对照任务(P=0.142)和简单乘法运算任务(P=0.880)之正确率差异无统计学意义,但老年组受试者完成对照任务(P=0.000)和简单乘法运算任务(P=0.005)反应时间明显延长。青年组受试者在任务刺激下可激活右侧缘上回并向顶内沟和颞中上回后部延伸,中央前回和运动前区、前额叶,左侧缘上回并向颞上回后部和角回延伸,顶内沟区域、颞中下回,内侧后扣带回、楔前叶、辅助运动区、海马沟、海马旁回及前额叶内侧;老年组受试者则分别激活右侧缘上回和顶下区域并向颞中上回后部延伸,中央前回和运动前区、前额叶,左侧缘上回和角回并向顶下延伸,中央前回和运动前区、岛叶及前额叶,内侧后扣带回和中央旁小叶、前扣带回及前额叶内侧;两组受试者共激活脑区包括顶下区域、楔前叶、中央前后回和额顶叶网络,以及颞叶、海马旁回、钩回、屏状核和后扣带回等皮质下结构。结论数学事实提取相关网络的主要成分受年龄影响较小,老年人群的任务激活脑区主要向任务相关顶区集中。  相似文献   

3.
ABSTRACT Few neuroimaging studies have explored gender differences on mental rotation tasks. Most studies have utilized samples with both genders, samples mainly consisting of men, or samples with six or fewer females. Graduate students in science fields or liberal arts programs (20 males, 20 females) completed a mental rotation task during functional magnetic resonance imaging (fMRI). When a pair of cube figures was shown, the participant made a keypad response based on whether the pair is the same/similar or different. Regardless of gender, the bilateral middle frontal gyrus, bilateral intraparietal sulcus (IPS), and the left precuneus were activated when a subject tried to solve the mental rotation task. Increased activation in the right inferior frontal gyrus/middle frontal gyrus, the left precuneus/posterior cingulate cortex/cuneus region, and the left middle occipital gyrus was found for men as compared to women. Better accuracy and shorter response times were correlated with an increased activation in the bilateral intraparietal sulcus. No significant brain activity differences related to mental rotation were found between academic majors. These findings suggest that networks involved in visual attention appear to be more strongly activated in the mental rotation tasks in men as compared to women. It also suggests that men use a more automatic process when analyzing complex visual reasoning tasks while women use a more top-down process.  相似文献   

4.
The neural substrate of gesture recognition   总被引:1,自引:0,他引:1  
Previous studies have linked action recognition with a particular pool of neurons located in the ventral premotor cortex, the posterior parietal cortex and the superior temporal sulcus (the mirror neuron system). However, it is still unclear if transitive and intransitive gestures share the same neural substrates during action-recognition processes. In the present study, we used event-related functional magnetic resonance imaging (fMRI) to assess the cortical areas active during recognition of pantomimed transitive actions, intransitive gestures, and meaningless control actions. Perception of all types of gestures engaged the right pre-supplementary motor area (pre-SMA), and bilaterally in the posterior superior temporal cortex, the posterior parietal cortex, occipitotemporal regions and visual cortices. Activation of the posterior superior temporal sulcus/superior temporal gyrus region was found in both hemispheres during recognition of transitive and intransitive gestures, and in the right hemisphere during the control condition; the middle temporal gyrus showed activation in the left hemisphere when subjects recognized transitive and intransitive gestures; activation of the left inferior parietal lobe and intraparietal sulcus (IPS) was mainly observed in the left hemisphere during recognition of the three conditions. The most striking finding was the greater activation of the left inferior frontal gyrus (IFG) during recognition of intransitive actions. Results show that a similar neural substrate, albeit, with a distinct engagement underlies the cognitive processing of transitive and intransitive gestures recognition. These findings suggest that selective disruptions in these circuits may lead to distinct clinical deficits.  相似文献   

5.
Background: Hypotheses regarding the neural substrates of writing have been derived from the study of individuals with acquired agraphia. Functional neuroimaging offers another methodology to test these hypotheses in neurologically intact individuals. Aims: This study was designed to identify possible neural substrates for the linguistic and motor components of writing in normal English-speaking individuals. Methods & Procedures: Functional magnetic resonance imaging was used with 12 adults to examine activation associated with generative writing of words from semantic categories contrasted with writing letters of the alphabet and drawing circles. In addition, the generative writing condition was contrasted with a subvocal generative naming condition. Outcomes & Results: Semantically guided retrieval of orthographic word forms for the generative writing condition revealed activation in the left inferior and dorsolateral prefrontal cortex, as well as the left posterior inferior temporal lobe (BA 37). However, no activation was detected in the left angular gyrus (BA 39). The motor components of writing were associated with activation in left fronto-parietal cortex including the region of the intraparietal sulcus, superior parietal lobule, dorsolateral and medial premotor cortex, and sensorimotor areas for the hand. Conclusions: These observations suggest an important role of the left posterior inferior temporal cortex in lexical-orthographic processing and fail to support the long-held notion that the dominant angular gyrus is the storage site for orthographic representations of familiar words. Our findings also demonstrate the involvement of left superior parietal and frontal premotor regions in translating orthographic information into appropriate hand movements.  相似文献   

6.
To explore the neural substrates of visual-tactile crossmodal integration during motion direction discrimination, we conducted functional magnetic resonance imaging with 15 subjects. We initially performed independent unimodal visual and tactile experiments involving motion direction matching tasks. Visual motion discrimination activated the occipital cortex bilaterally, extending to the posterior portion of the superior parietal lobule, and the dorsal and ventral premotor cortex. Tactile motion direction discrimination activated the bilateral parieto-premotor cortices. The left superior parietal lobule, intraparietal sulcus, bilateral premotor cortices and right cerebellum were activated during both visual and tactile motion discrimination. Tactile discrimination deactivated the visual cortex including the middle temporal/V5 area. To identify the crossmodal interference of the neural activities in both the unimodal and the multimodal areas, tactile and visual crossmodal experiments with event-related designs were also performed by the same subjects who performed crossmodal tactile-visual tasks or intramodal tactile-tactile and visual-visual matching tasks within the same session. The activities detected during intramodal tasks in the visual regions (including the middle temporal/V5 area) and the tactile regions were suppressed during crossmodal conditions compared with intramodal conditions. Within the polymodal areas, the left superior parietal lobule and the premotor areas were activated by crossmodal tasks. The left superior parietal lobule was more prominently activated under congruent event conditions than under incongruent conditions. These findings suggest that a reciprocal and competitive association between the unimodal and polymodal areas underlies the interaction between motion direction-related signals received simultaneously from different sensory modalities.  相似文献   

7.
The neural substrate of arithmetic operations and procedure complexity   总被引:2,自引:0,他引:2  
Recent functional neuroimaging studies have begun to clarify how the human brain performs the everyday activities that require mental calculation. We used fMRI to test the hypotheses that there are specific neural networks dedicated to performing an arithmetic operation (e.g. + or -) and to performing processes that support more complex calculations. We found that the right inferior parietal lobule, left precuneus and left superior parietal gyrus are relatively specific for performing subtraction; and bilateral medial frontal/cingulate cortex are relatively specific for supporting arithmetic procedure complexity. We also found that greater difficulty level was associated with activation in a brain network including left inferior intraparietal sulcus, left inferior frontal gyrus and bilateral cingulate. Our results suggest that the network activated by the simplest calculation serves as a common basis, to which more regions are recruited for more difficult problems or different arithmetic operations.  相似文献   

8.
By means of autoradiographic and ablation-degeneration techniques, the intrinsic cortical connections of the posterior parietal cortex in the rhesus monkey were traced and correlated with a reappraisal of cerebral architectonics. Two major rostral-to-caudal connectional sequences exist. One begins in the dorsal postcentral gyrus (area 2) and proceeds, through architectonic divisions of the superior parietal lobule (areas PE and PEc), to a cortical region on the medial surface of the parietal lobe (area PGm). This area has architectonic features similar to those of the caudal inferior parietal lobule (area PG). The second sequence begins in the ventral post/central gyrus (area 2) and passes through the rostral inferior parietal lobule (areas PG and PFG) to reach the caudal inferior parietal lobule (area PG). Both the superior parietal lobule and the rostral inferior parietal lobule also send projections to various other zones located in the parietal opercular region, the intraparietal sulcus, and the caudalmost portion of the cingulate sulcus. Areas PGm and PG, on the other hand, project to each other, to the cingulate region, to the caudalmost portion of the superior temporal gyrus, and to the upper bank of the superior temporal sulcus. Finally, a reciprocal sequence of connections, directed from caudal to rostral, links together many of the above-mentioned parietal zones. With regard to the laminar pattern of termination, the rostral-to-caudal connections are primarily distributed in the form of cortical "columns" while the caudal-to-rostral connections are found mainly over the first cortical cell layer.  相似文献   

9.
Learning complex arithmetic--an fMRI study   总被引:5,自引:0,他引:5  
Aim of the present functional magnet resonance imaging (fMRI) study was to detect modifications of cerebral activation patterns related to learning arithmetic. Thirteen right-handed subjects were extensively trained on a set of 18 complex multiplication problems. In the following fMRI session, trained and untrained problems (closely matched for difficulty) were presented in blocked order alternating with a number matching task and a fact retrieval task. Importantly, left hemispheric activations were dominant in the two contrasts between untrained and trained condition, suggesting that learning processes in arithmetic are predominantly supported by the left hemisphere. Contrasting untrained versus trained condition, the left intraparietal sulcus showed significant activations, as well as the inferior parietal lobule. A further significant activation was found in the left inferior frontal gyrus. This activation may be accounted for by higher working memory demands in the untrained as compared to the trained condition. Contrasting trained versus untrained condition a significant focus of activation was found in the left angular gyrus. Following the triple-code model [Science 284 (1999) 970], the shift of activation within the parietal lobe from the intraparietal sulcus to the left angular gyrus suggests a modification from quantity-based processing to more automatic retrieval. The present study shows that the left angular gyrus is not only involved in arithmetic tasks requiring simple fact retrieval, but may show significant activations as a result of relatively short training of complex calculation.  相似文献   

10.
The posterior insula, central sulcus, and inferior parietal lobule including the intraparietal sulcus have been considered the vestibular cortex based on functional brain mapping in humans as well as experiments in lower primates. The same regions receive optokinetic, visual, and proprioceptive projections. We examined the cortical and subcortical projection of vestibular activity with visual and proprioceptive input eliminated during caloric stimulation (CS), using functional magnetic resonance imaging (fMRI). Single-shot gradient-echo echoplanar image (EPI) volumes were sensitive to BOLD contrast in oblique orientation. We adopted a pharmacokinetic model for analysis of imaging data from 10 subjects as a group. The insular gyrus, intraparietal sulcus, superior temporal gyrus, hippocampus, cingulate gyrus, and thalamus showed activation by CS. Cortical and subcortical activation during CS in the present study was observed within regions less precisely delineated by other methods. As intraparietal sulcus activation showed right hemispheric dominance, this region may have an oculomotor projection as well as the vestibular input.  相似文献   

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