| The acute cerebral infarction is one of the common diseases in neuropathy, with a high morbidity and mutilation. With the development of neuroscience, especially the clinical application of neuroimaging techniques such as CT and MRI, the quantity, size and location of focus can be found very early, but the degree of impairment in cerebral functions cannot be reflected directly. It is disadvantage to measure the injury of cerebral function directly and objectively and select the most effective therapy. Magnetoencephalography (MEG) is a new type of cerebral function detecting techniques advent in the late 1960, which can measure and locate cerebral magnetic signals noninvasively and precisely. With super-conducting quantum interfere device (SQUID) and magnetically shielded systems, it can detect the weak magnetic fields produced by cerebral activities. Because the effects on cerebral magnetic signals were very week when they transmitted through the intermediary agents such as cerebrospinal fluid, skull and scalp, the temporal and spatial resolution of MEG is very high. It can detect the location and origination of cerebral magnetic fields precisely, with great value in clinical application.Language speaking is a characteristic senior function of human brain. And picture naming is one of the most characteristic tasks in language production. All core components of word production are involved in picture naming. Studying picture naming is helpful for us to reveal the pathogeny in acquired disordiers of languge. The injury to occipital lobe can lead to visual loss in contralateral view field. However, part of vision in view field with lesion can be reserved. To realize the extent of loss of cortical funtion after injury and the mechanism of reparative process can help us to appraise the reorganization and reconstitution of the function of visual cortex, appraise the efficacy of rehabilitation exercise objectively and seek the ideal method for visual function recovery. In the past, scholars have carried out several studies about that. However, due to limitations of above measurement, it is difficult to directly study the lingual function of human brain.We measured cerebral evoked magnetic fields of healthy objects and patients of acute cerebral infarction by 306-channels MEG to study (1) event-related fields (ERFs) in picture naming task in patients with acute cerebral infarction; (2) visual evoked fields (VEFs) in patients with acute cerebral infarction. The results are as follows:1 Brain language functional composition in picture naming task in patients with acute cerebral infarction by magnetoencephalography Objective: To study ERFs in picture naming task in patients with acute cerebral infarction by MEG.Methods: 13 patients with acute cerebral infarction showing motor aphasia and 10 healthy volunteers were ordered to carry out the cognitive task of picture naming, at the same time, they were measured with 306-channel whole-head MEG. The stimuli were 100 pictures of common items. In the task, these unpracticed pictures were sequently named, the time of duration and interval was respectively 1000ms and 2000ms.Results: During the task of picture naming, following focal brain activities were found: bilateral occipital lobe, bilateral occipito-temporal areas, dominant Wernicke's area, dominant Broca's area, etc. There were several abnormal parameters in the patient group: (1) the strength of ECD in dominant Wernicke's area was significantly smaller than that in the healthy group (P<0.05); (2) the strength of ECD in dominant Broca's area was significantly smaller than that in the healthy group (P<0.05); the peak latency in this area in the patient group was significantly longer than that in the healthy group (P<0.05).Conclusions: Latent functional impairment may be evaluated by MEG with high spatial and temporal resolution. MEG provides objective and sensitive indexes to evaluate the function of word production cortex in patients with acute cerebral infarction.2 The clinical study of visual evoked fields in patients with acute occipital lobe infarction by magnetoencephalographyObjective: To study VEFs in patients with acute cerebral infarction by MEG.Methods: The peak latency, strength of ECD and magnetic source imaging (MSI) of VEFs were recorded from 6 patients with acute cerebral infarction in one hemisphere occipital lobe showing homonymous hemianopia and 8 healthy volunteers using 306 channel whole-head MEG. In the task, all participants were sequently given pattern reversal stimuli of vertical half field and quadrant field, the time of interval was 2 min.Results: M100 was the most elemental components of VEFs in all subjects, originating from the area around the calcarine sulcus. The activities of the VEFs in contralateral hemispheric occipital lobe to the lesion were similar with normal people. However, the activities of occipital lobes with lesion had some difference from normal people including abnormal waveforms and locations, prolonged latency and decreased strength of ECD of M100.Conclusions: Latent cortical impairment may be evaluated by MEG with higher spatial and temporal resolution. MEG provides objective and sensitive indexes to evaluate the function of visual cortex in patients with acute cerebral infarction in occipital lobe. |
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