| The goal of surgery in the treatment of intrinsic cerebral tumors is to resect the maximum neurologically permissible tumor volume, and to spare the eloquent areas that are associated with the control of motor, sense, language, or memory, and other cognitive functions. The key of this kind of surgery is an accurate real-time brain mapping for eloquent areas. Accurate mapping of eloquent areas can avoid both post-operative permanent neurological sequelae caused by intra-operatively damage to the eloquent areas, and a premature interruption of the resection by a "coward" surgical strategy. Brain mapping for motor and/or sensory can be accurately achieved not only by preoperative functional magnetic resonance imaging, but also by direct electrical stimulation. However, mapping of the language, memory, or other cognitive functions remains a problem for current surgical treatment of lesions harbored in the eloquent areas.Language is one of higher cognitive functions unique to the human beings. Language-related cortices are much broader and more complex than that of motor and/or sensory function. The language cortices vary among individuals, and this variation is much more apparent when patients have brain lesions near language cortices. How to map cortical areas for language is critical to the surgery of lesions located in the dominant hemisphere, particularly in areas close to language-related cortices. It gradually becomes a neurosurgical research hot spot for maximally resection of lesions in brain language areas, and meanwhile, minimally damage to the eloquent areas.Intra-operative direct electrical stimulations have been regarded as the "gold standard" in defining cortical and subcortical pathways of the language areas. This technique minimizes definitive post-operative neurological deficit while concurrently improves the quality of resection. However, it is necessary to stress that the technique can also result in "false positives" and "false negatives" even when direct electrical stimulations are properly used. Consequently, "false positives" could wrongly lead to a premature interruption of the resection, whereas "false negatives" could result in permanent neurological sequelae.There are several causes for "false negatives", such as an intensity of stimulation that is too low and stimulation that lasts too short a time or is performed during a transient post-epileptic refractory phase, which may lead to an erroneous technically "negative mapping". Nevertheless, such errors can be avoided by strictly following the practical rules of stimulation.Another cause for false negatives is an inappropriate intra-operative task for functional mapping. Counting, reading and naming are the three mostly used intra-operative tasks for mapping of language. Naming of pictures of objects is the basic task used in mapping procedures because naming is a core component in language abilities and is supposed to be a reliable method for identifying essential language sites. Patients are asked to name a set of line drawing of objects when the stimulation probes are placed at a cortical site. The pictures shown intra-operatively include pictures of animals, birds, fruits, vegetables, man-made objects, etc. They are blended in one naming task. However, cortical sites for naming may vary among different categories. This may results in a "false negative" mapping. Therefore, study on mapping of the category-specific naming cortices can help us to choose a more appropriate intra-operative task for functional mapping which can decrease the postoperative permanent morbidity.In this essay, we firstly conducted a blood oxygen level dependent-functional magnetic resonance imaging (BOLD-fMRI) study to map the category-specific sites associated with naming of famous faces, animals and tools in health Chinese volunteers. Then, the functional connectivity of the activated clusters was calculated by rest-state fMRI. In the third part, we investigated the category-specific naming sites in patient with brain lesions near eloquent areas by both BOLD-fMRI and direct electrical stimulation. The goal of this study was to test the hypothesis of dissociation of category specific naming area in cerebral cortices. The study will contribute to a better understanding of special functions in certain cortices, to help neurosurgeons choose more appropriate intra-operative tasks for functional mapping, and further to avoid postoperative permanent aphasia, and to improve the postoperative quality of life in patients with lesions near eloquent area.Part I A functional MRI study of mapping category-specific sites associated with naming of famous faces, animals and tools.Objective:To study the category specific cortices for naming famous faces, animals and tools in health volunteers.Methods:21 Chinese health volunteers were recruited to study the specific invoked areas involved in naming pictures of these three categories using BOLD-fMR. Functional images were analyzed using statistical parametric mapping (SPM8), and the region of interest (ROIs) was analyzed using Marsbar0.42.Results:Naming famous faces caused more activation in the bilateral medial parts of anterior temporal lobe (including head of hippocampi and amygdala with a significant left dominance). Bilateral activation of pars triangularis and pars opercularis in the naming of famous faces was also discovered by this study. Naming animals invoked greater responses in the left supplementary motor areas, while naming tools invoked more in left premotor areas and right supplementary motor areas. The extent of activated bilateral fusiform gyri by naming of tools was much larger than that by naming of famous faces or animals.57 regions of interest were analyzed by one-way ANOVA, and 14 of 57 activated clusters were shown statistically significant among three categories (P<0.05). They included bilateral medial parts of anterior temporal lobe, right anterior insula, right pars triangularis and pars opercularis in the naming of famous faces, and the right superior occipital gyrus and left pars orbitalis and bilateral fusiform gyri in naming of tools. There were no significant specific activated clusters in naming of animal.Conclusion:The brain cortices involved in the naming process will vary from naming of famous faces, animals and tools. And the category specific naming sites are extensive. This finding suggests that various categories of pictures should be adopted during intra-operative language mapping to get a broader map of language function, in order to minimize the incidence of false-negative stimulations and permanent post-operative deficits.Partâ…¡Rest state functional connectivity of category-specific naming areas in health volunteers.Objective:To study the network distributed cortices related to the activated clusters specific for naming famous faces, animals and tools.Methods:Resting-state fMRI data from 21 healthy volunteers were analyzed the functional connectivity by software REST v1.3 to obtain with network distributed cortices closely related to the "seed voxles" that were picked based on activated clusters specific for naming famous faces, animals or tools.Results:Three types of naming tasks activated a broader network of brain regions Naming famous faces network mainly included bilateral medial parts of anterior temporal lobe and right pars triangularis and pars opercularis. It also included bilateral posterior middle frontal gyrus, bilateral temporal pole, left lateral side of pariet-occipital lobe, left middle and inferior temporal gyrus. Naming animals'network are mainly located in supplementary motor areas, bilateral posterior middle temporal gyrus, and bilateral posterior middle frontal gyrus with a significant left dominance, bilateral inferior frontal gyrus and superior parietal lobule, and left inferior parietal lobule. While naming tools' network was mainly consisted of left premotor area, right anterior superior occipital gyrus, bilateral parietal lobe, posterior middle frontal gyrus and temporal pole, and left medial temporal lobe, left posterior of superior frontal gyrus.Conclusion:The cortical network involved in different types of naming process overlaps in some cortices. There are also certain differences in activated areas among the three categories. And the category specific naming networks are rather extensive. This finding suggests that some more preoperative examinations are needed to clarify the naming cortices when surgeries are involved in certain areas.Partâ…¢Clinical study on brain mapping of category-specific naming corticesObjective:To study the category specific cortices for naming famous faces, animals and tools in patients with lesions near eloquent areas.Methods:Naming sites for different categories of naming tasks were evaluated by the BOLD-fMRI in 18 patients with brain lesions in cerebral hemisphere. Then during awake procedures, the category specific naming cortices were detected by intraoperative direct electrical stimulation using a category specific naming task.Results:â‘ Using BOLD-fMRI, we found that the common regions activated by naming the three categories of picture were the posterior parts of left middle frontal gyri, pars triangularis of left inferior frontal gyri, supplementary motor areas and bilateral fusiform gyri. There were also category-specific brain regions:Naming famous faces caused more activation in the bilateral temporal poles and head of hippocampi, and right anterior insula. But the differences among three groups are not statistically significant (P> 0.05). Naming tools invoked greater responses in bilateral superior parietal lobule and posterior parts of right middle frontal gyrus.â‘¡Intraoperative direct electrical stimulation has also confirmed the existence of famous face-specific naming regions that are distributed extensively, mainly in the left temporal pole, posterior parts of left inferior or superior frontal gyrus and left supramarginal gyrus. The common areas interfered by stimulation when perform naming famous faces, animals and tools were left supramarginal gyrus, posterior parts of left middle frontal gyrus and left inferior frontal gyrus, and the posterior parts of left superior temporal gyrus. There was no cortex specific for naming of animals, or naming of tools, or naming of both famous faces and tools. The middle parts of left temporal lobe were found for naming both famous faces and animals. Other regions for both naming animals and naming tools are mainly located in the posterior parts of left inferior frontal gyrus, middle frontal gyrus and left temporal lobe.Conclusion:The brain cortices involved in the naming process varies from naming of famous faces, animals and tools. There are some cortices exclusively for naming of famous faces. Cortices for naming of animals can be activated by naming of famous faces or tools. This finding suggests pictures of famous faces should be adopted during intra-operative language mapping to get a broader map of language function, in order to minimize the incidence of "false-negative" stimulations and permanent post-operative deficits, and to improve the patient's postoperative quality of life.
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