We reviewed the present status of pre- and intraoperative functional mapping and monitoring for brain tumor surgery. Functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) have become gold standards to identify the central sulcus with electrical stimulation to the median nerve and language lateralization using word reading or verb generation tasks. For white matter mapping, diffusion tensor imaging (DTI) -based tractography is the only technique available, which visualizes the eloquent subcortical fibers including the corticospinal tract (CST) and the arcuate fascicles (AF). Cortical somatosensory evoked potentials, motor evoked potentials (MEP) with cortical and subcortical stimulation, and awake craniotomy are available for intraoperative functional monitoring. There were strong correlations between stimulus intensity for MEP with the fiber stimulation and the distance between CST and the stimulus points. The results indicate that a minimum stimulus intensity of 20, 15, 10 and 5 mA had stimulus points of approximately 20, 15, 10 and 5 mm far from CST, respectively. Subcortical electrical stimulation to AF consistently induced paranomia during awake craniotomy. These facts indicate that tractography is a reliable technique for brain tumor resection. Finally, even though fluorescent imaging has the potential to navigate us to the tumor border, it is still necessary to develop quantitative analyses for this technique.

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  The ability to evaluate brain function pre- and intra-operatively has been essential in maintaining the quality of life in patients undergoing functional neurosurgery. These evaluations which were originally developed for studies in epilepsy are now essential in neurosurgery for brain tumors and vascular diseases. The goal of functional brain mapping augumented by function monitoring, is to perform surgery more safely and effectively for better outcomes. Among the multiple modern modalities for brain functional evaluation, we should consider the physiological aspects of each of these methods from a view point of functional recovery or compensation. Clinical usefulness and differences between intraoperative electrical stimulation of the motor cortex and subcortical fibers (i.e., pyramidal tracts) and voluntary movement to preserve affected or unaffected motor function during neurosurgery is also discussed. Further consideration of the network among each eloquent area may lead to a new concept in neurosurgery as well as neuroscience.

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  In this review, the functional localization of schizophrenia and depression, the two most common and representative psychiatric disorders, is described. Recent neuroimaging techniques have demonstrated various structural and functional brain abnormalities present in schizophrenia. These abnormalities, specifically focused in the frontal and temporal lobes, have functional relevance with positive symptoms of schizophrenia including auditory hallucinations and delusions. In addition, schizophrenia has been shown to have neural network abnormalities in the social brain, which subserves social and interpersonal relationships. Functional neuroimaging studies including SPECT, PET, NIRS and fMRI have repeatedly demonstrated hypofrontality in depression. It is important to note that such hypofrontality or functional impairment in depression may remain even after the clinical symptoms of depression have resolved. Longitudinal studies using various treatment strategies including pharmacotherapy, cognitive behavioral therapy and deep brain stimulation have widely contributed to understanding the mechanisms of functional recovery of the emotion-related neural network.

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  Non-invasive neuroimaging techniques such as functional MRI enable us to relate psychological events to brain event locations. By linking the location-specific neuro-scientific and/or neurological information with psychological theory, this method can provide the constraints necessary to construct the psychological model. Given that the constructs are decomposable along the line of time (development) ; functional MRI in adult subject may provide useful information for constructing the social cognition development model. An approach to develop social cognition toward the prosocial behavior is presented.
  People are motivated not only by materialistic rewards but also by abstract social rewards such as good reputation. We first investigated whether acquiring a good reputation activates the same reward circuitry as monetary rewards. Subjects participated in fMRI experiments involving monetary and social rewards. The acquisition of one's good reputation robustly activated reward-related brain areas, notably the striatum, and these overlapped with the areas activated by monetary rewards. This finding indicates that the experienced utilities of both social and monetary rewards are represented in the striatum. Secondly, to investigate how reputation influences an altruistic behavior such as making a donation, we investigated the activation of the striatum when individuals freely decided whether to donate to real charities or take the money for themselves in the presence or absence of observers. Behavioral evidence showed that the mere presence of observers increased donation rates, and neuroimaging results revealed that activation in the ventral striatum before the same choice (“donate” or “not donate”) was significantly modulated by the presence of observers. These findings highlight the importance of the striatum in representing both social and monetary rewards acting as a “decision utility” and add to the understanding of how the brain makes a choice using a “common neural currency” in social situations.

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  Recently, a new neuroangiography system equipped with a flat-panel X-ray detector (FPD) capable of taking cone-beam CT images, the XperCT from Philips C-arm, was introduced. It overlays live fluoroscopy and XperCT imaging data to provide real time information on the needle pathway and target during surgery. We report our experience using this XperGuide technology for acute hydrocephalus associated with intracranial aneurysm in 8 cases. All XperGuide assisted neurosurgery were successful without any technical and neurological complications. XperGuide assisted neurosurgery provides real time visualization of surgical equipment and achieves accurate positioning, and contributes improved working flow and patient care.

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  Long-term results of radiosurgery for lower cranial nerve schwannomas are reported. There are 33 cases, including 11 males and 22 females, whose age ranging from 26 to 76 years (mean : 47.3 years). Many of them presented with lower cranial nerve signs like swallowing disturbance, hoarseness, hemiatrophy of tongue. As prior treatments, 17 cases underwent surgical resection and the other 16 were diagnosed with neurological and radiological findings. Tumor size at radiosurgery was 25 mm in mean diameter, and they were treated with a mean marginal dose of 13.3 Gy. Tumors showed excellent responses, indicating 1 CR, 23 PR, 9 NC during the mean follow-up period of 83 months. Cyst enlargement was the main cause of progression in 2 cases, and became stable after cyst evacuation. No adverse effects were confirmed in this series. Functionally, chief signs of swallowing disturbance and hoarseness were considerably improved, but tongue atrophy, hearing loss and ataxia were not. In our scoring system evaluating tumor control, functional outcome as well as adverse effects, lower cranial nerve schwannomas demonstrated best score among various intracranial schwannomas. Both large and dumbbell-shaped tumors should be surgically removed, however, small tumors especially the ones in and around the jugular foramen can be treated with radiosurgery.

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  Brainstem cavernous malformations account for 9-35% of all intracranial cavernous malformations and most brainstem cavernous malformations arise from the pons. Pontine cavernous malformations remain surgically challenging because of their deep-seated and eloquent locations. Although several approaches have been reported to remove pontine cavernous malformations, there are only a few reports available regarding the transpetrosal approach in pontine cavernous malformation surgery. Here, we report our experience in treating patients with pontine cavernous malformations by the transpetrosal approach. Furthermore, alternate surgical approaches to pontine cavernous malformations will be discussed.
  A total of six cases were included in this study. There were four men and two women with an average age of 46.2 years. All cases presented neurological deficits caused by hemorrhage before surgery. The anterior transpetrosal approach was used in four and a combined transpetrosal approach was used in two cases. Gross total removal was achieved in all cases with an acceptable surgical outcome.
  We consider that a small cortical incision which allows multi-direction dissection is the most important factor to avoid additional neurological deficits in cavernous malformation surgeries. Therefore, the transpetrosal approach can be used to minimize neurological deficits after removal of pontine lesions.

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  Tardive dystonia (TD) is a disabling movement disorder associated with exposure to neuroleptic drugs. It is usually irreversible and its medical treatment is notoriously difficult. We performed bilateral deep brain stimulation (DBS) of the globus pallidus internus (GPi) to treat a severe case of TD.
  A 49-year-old woman, who was administered antidepressants and hypnotics due to manic-depressive psychosis since she was 25 years old, had been suffering TD on her neck and trunk for 7 years and her symptoms gradually deteriorated. Every medical therapy tried, failed to improve her symptoms, and her ability of daily living was severely impaired by the dystonia. Bilateral GPi-DBS was performed under general anesthesia. The retrocollis and posterior bending of the trunk were remarkably alleviated immediately after stimulation. Afterward, her dystonic posture gradually improved over the course of a seven months follow-up period. Her depression did not worsen after surgery, and because she was now able to lie in a supine position without uncomfortable dystonic movement, her insomnia even improved.
  Bilateral GPi-DBS is a very effective therapy for TD, as well as for primary generalized dystonia. The surgical indication should be considered positively, though the patients with TD essentially have a psychotic disease. Intraoperative electrophysiological identification of the target is essential to detect the optimal location to place the electrodes in the GPi.

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