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Mental rotation is a spatial representation conversion capability using an imagined object and either object or self-rotation. This capability is impaired in schizophrenia.To provide a more detailed assessment of impaired cognitive functioning in schizophrenia by comparing the electrophysiological profiles of patients with schizophrenia and controls while completing a mental rotation task using both normally-oriented images and mirror images.This electroencephalographic study compared error rates, reaction times and the topographic map of event-related potentials in 32 participants with schizophrenia and 29 healthy controls during mental rotation tasks involving both normal images and mirror images.Among controls the mean error rate and the mean reaction time for normal images and mirror images were not significantly different but in the patient group the mean (sd) error rate was higher for mirror images than for normal images (42% [6%] vs. 32% [9%], t=2.64, p=0.031) and the mean reaction time was longer for mirror images than for normal images (587 [11] ms vs. 571 [18] ms, t=2.83, p=0.028). The amplitude of the P500 component at Pz (parietal area), Cz (central area), P3 (left parietal area) and P4 (right parietal area) were significantly lower in the patient group than in the control group for both normal images and mirror images. In both groups the P500 for both the normal and mirror images was significantly higher in the right parietal area (P4) compared with left parietal area (P3).The mental rotation abilities of patients with schizophrenia for both normally-oriented images and mirror images are impaired. Patients with schizophrenia show a diminished left cerebral contribution to the mental rotation task, a more rapid response time, and a differential response to normal images versus mirror images not seen in healthy controls. Specific topographic characteristics of the EEG during mental rotation tasks are potential biomarkers for schizophrenia.心理旋转(mental rotation)是一种想象客体或自我旋转的空间表征转换能力。精神分裂症患者的心理旋转能力受损。记录精神分裂症患者和健康对照者完成正像和镜像心理旋转任务时的脑电生理指标，比较这些指标的差异，深入评估精神分裂症患者的认知损害情况。对来自解放军第三医院精神科32例精神分裂症患者和29例健康对照者在完成正像和镜像的心理旋转任务时的事件相关电位测定，比较两组错误发生比例、反应时以及事件相关电位的脑地形图。对照组正像与镜像的错误率比较无明显差异，正像与镜像的反应时间亦无明显差异。而患者组镜像的平均（标准差）错误率比正像高 [42%（6%）比32%（9%），t=2.64，p=0.031]，患者组镜像的反应时比正像长 [587（11）ms比571（18）ms，t=2.83，p=0.028]。无论是镜像还是正像，患者组Pz（顶区）、Cz（中央区）、P3（左侧顶区）和P4（右侧顶区）的P500波幅均低于对照组。与P3极点相比，两组正像和镜像P4点波幅都偏高。精神分裂症患者正像和镜像心理旋转能力都受损。患者大脑左半球心理旋转能力减弱，反应时缩短，对正像与镜像反应存在差异，这些都与对照组不同。研究提示完成心理旋转任务时特定的脑地形图可作为诊断精神分裂症的一个辅助参考指标。

The ability to mentally rotate images is impaired in depressed patients but the electrophysiological abnormalities in the brain related to this impairment remain unclear.To compare the event-related potentials (ERPs) of depressed patients and control subjects during the completion of a mental rotation (MR) task.Thirty-two inpatients and outpatients with first-episode depression and twenty-nine control subjects were administered an MR task that presented test stimuli at different angles of orientation. During the test ERPs were measured in four regions of the brain (PZ, CZ, P3 and P4). Outcome variables included the error rate, reaction time, P500 latency and maximum P500 amplitude.Compared to control subjects, patients with depression completing the MR test had a significantly longer mean (sd) reaction time (689 [98] ms vs. 569 [55] ms; t=4.36, p0.001) and a significantly higher mean percent error rate (30.2% [11.4%] vs. 20.3% [7.2%]; t=3.61, p=0.015); these differences were also significant at each of the four orientation angles assessed. The ERP assessment during the MR test found that patients had a non-significant increase in the overall P500 latency and a significant reduction in the mean maximum P500 amplitude at each of the four brain regions assessed. For both patients and controls the error rate, reaction time, P500 latency and P500 amplitude increased significantly in a stepwise fashion as the angle of orientation of the presented stimulus increased from 0° to 180°. In the control group there was a positive peak in the averaged ERP waveforms at about 700 ms that was not present in the patient group.Our study confirms previous work on the usefulness of MR tests to assess the cognitive deficits in depression. We find that the electrophysiological measures provided by ERP assessments during MR tasks, particularly maximum P500 amplitude and maximum P700 amplitude, are potential biological markers for depression. Prospective studies that assess changes in these measures over the course of a depressive illness will be needed to confirm their usefulness.抑郁症患者的心理旋转意象能力受损，但与其脑相关联的异常脑电生理机制仍不清楚。比较抑郁症患者与健康对照完成心理旋转任务时的事件相关电位（event-related potentials，ERPs）的差异。对32例住院或门诊首发抑郁症患者和29名对照进行心理旋转任务的ERP测定，给予不同旋转角度的测试刺激。测定4个脑区的ERPs（PZ、CZ、P3和P4）。测量指标包括错误数、反应时、P500潜伏期和波峰值。与对照组相比，患者组完成心理旋转任务的反应时显著延长[689(98)ms 比 569 (55)ms; t=4.36, p0.001]，错误率显著升高[30.2%(11.4%)比20.3%(7.2%); t=3.61, p=0.015]，且在所有4个旋转角度均有差异。完成心理旋转任务时的事件相关电位测定发现，抑郁症患者在4个脑区的总P500潜伏期有所增加，但无统计学意义，而P500波峰值显著降低。患者组与对照组的错误率、反应时、P500潜伏期及波峰值均随着旋转角度（0°~180°）的递增而呈逐渐增加。对照组平均ERP波形在700ms处出现一个正波峰，而在患者组未见。本研究证实了既往研究利用心理旋转任务评定抑郁症患者认知功能缺陷的有效性。本研究发现心理旋转任务诱发的事件相关电位的电生理指标，特别是P500及P700波峰值，可能是抑郁症的潜在生物学标记。需要前瞻性研究测定上述指标在抑郁症病程中的变化，以证实其有效性。