局灶性脑缺血再灌注大鼠过氧化物酶体增殖物激活受体γ核移位的改变

目的 观察过氧化物酶体增殖物激活受体γ(PPARγ)在脑缺血再灌注损伤中核移位的改变,并初步探讨该改变在脑缺血损伤中的意义.方法 健康雄性SD大鼠制作大脑中动脉阻塞再灌注模型,缺血60 min,再灌注4、8、24 h.采用Western blot法、免疫组织化学和免疫荧光染色法观察PPARγ核移位的改变以及PPARγ激动剂和拮抗剂对PPARγ核移位的影响;同时,2,3,5-氯化三苯四唑(TTC)染色法观察脑梗死体积的改变.结果 (1)Western blot检测显示,脑缺血再灌注4 h即引起PPARγ核蛋白增加,同时胞质蛋白减少,差异具有统计学意义.随再灌注时间的增加,PPARγ核移位呈时间依赖性增强.免疫组织化学和免疫荧光染色均显示,与假手术组48.3%相比,缺血再灌注24 h胞核PPARγ阳性增加到80.3%,差异具有统计学意义(t=8.63,P=0.00).(2)与单纯缺血再灌注组相比,PPARγ激动剂进一步增加PPARγ核蛋白表达,同时减少胞质蛋白表达,差异均具有统计学意义;相反,PPARγ抑制剂GW9662则降低核蛋白水平而增加胞质表达,差异均具有统计学意义.(3)经TTC染色显示,与单纯缺血再灌注组相比,PPARγ激动剂使脑梗死体积减少了48.40%(15.46±4.94与29.96 ±3.39,t=5.93,P=0.00);而PPARγ抑制剂则使脑梗死体积增加了58.95%(47.62±4.93与29.96±3.39,t=7.23,P=0.00).结论 脑缺血再灌注损伤使大鼠PPARγ核移位增加,该改变可能是脑组织的一种自我保护性反应.     

过氧化物酶体增殖物激活受体γ激动剂对小鼠局灶性脑缺血再灌注损伤的保护作用

目的 探讨过氧化物酶体增殖物激活受体γ(pemxisome proliferator-activated receptor gamma,PPARγ)激动剂对小鼠局灶性脑缺血再灌注损伤的保护作用及其机制.方法 制作小鼠大脑中动脉阻塞再灌注(MCAO/R)模型.分别采用3%氯化三苯四唑(TTC)染色法、神经功能缺损评分法观察PPARγ激动剂对小鼠脑梗死体积和行为学的影响;紫外分光光度法检测脑组织髓过氧化物酶(myeloperoxidase,MPO)活性;逆转录一聚合酶链反应、免疫组织化学、Western blot法观察炎性因子[细胞间黏附因子-1(ICAM-1)、白细胞介素-1β(IL-1β)、环氧合酶-2(COX-2)]mRNA和蛋白表达变化.结果 PPARγ激动剂能够显著降低小鼠脑梗死体积(mm3,29.1±6.6,模型组为57.8±9.7,t=5.980,P<0.01)和行为学评分(1.2±0.4,模型组3.3±0.8,t=5.812,P<0.01);能减轻缺血脑组织MPO活性(U/g,0.049±0.005,模型组0.083±0.008,t=5.904,P<0.01);减少缺血脑组织炎性因子ICAM·1、IL-1β和COX-2 mRNA表达和蛋白表达.结论 PPARγ激动剂对小鼠脑缺血再灌注损伤有一定的保护作用,其作用机制与减轻缺血脑组织的炎症反应有关.     

缺血预处理对局灶性脑缺血再灌注大鼠缺血侧海马CA1区低氧诱导因子-1α及存活素表达的影响

目的探讨缺血预处理对局灶性脑缺血再灌注大鼠缺血侧海马CA1区低氧诱导因子-1α(HIF-1α)及存活素表达的影响。方法健康雄性SD大鼠130只随机分为假手术组(SO组,n=10)、局灶性脑缺血再灌注组(MCAO组,n=60)、缺血预处理组(BIP组,n=60),MCAO组和BIP组又分别分为再灌注2 h、6 h、12h、24 h、48 h、72 h 6个亚组,每亚组10只大鼠。采用线栓法制备大鼠脑缺血再灌注模型。BIP组在缺血前24h给予10 min的预缺血。采用免疫组化染色法检测HIF-1α、存活素的阳性细胞数。采用Western blot法检测HIF-1α、存活素的蛋白相对含量。结果与SO组比较,MCAO组和BIP组各时间点亚组大鼠缺血侧海马CA1区HIF-1α及存活素的阳性细胞数及蛋白相对含量均明显升高(均P0.05)。与MCAO组比较,BIP组各时间点亚组大鼠缺血侧海马CA1区HIF-1α及存活素的阳性细胞数及蛋白相对含量均明显升高(均P0.05)。在MCAO组和BIP组中,大鼠缺血侧海马CA1区HIF-1α及存活素的阳性细胞数及蛋白相对含量均在再灌注24 h时达到最高峰(均P0.05)。结论缺血预处理能够诱导局灶性脑缺血再灌注大鼠缺血侧海马CA1区HIF-1α、存活素表达上调,这或许与脑缺血耐受的产生机制有关。     

BMP-7对大鼠脑缺血再灌注损伤后Caspase-9表达的影响

目的观察骨形态发生蛋白-7(BMP-7)对大鼠脑缺血再灌注损伤后皮质Caspase-9表达的影响,探讨其神经保护机制。方法成年雄性Wistar大鼠40只,随机分为假手术组、模型组、BMP-7治疗组(0.1 mg/kg,0.2 mg/kg),每组10只,模型组和BMP-7治疗组采用线栓法制作大脑中动脉缺血再灌注模型,Longa评分法进行神经功能评分,HE染色观察缺血侧皮质病理学变化,实时定量RT-PCR法检测Caspase-9 mRNA的表达,免疫组织化学法及Western blot法检测Caspase-9蛋白的表达。结果与模型组相比,BMP-7治疗组大鼠神经功能评分明显降低(t=3.79,t=4.43,P<0.01),HE染色显示缺血侧皮质脑组织病理损伤减轻,且以高剂量组较为明显,实时定量PCR显示Caspase-9 mRNA表达明显降低(t=2.56,t=4.52;P<0.05,P<0.01),Western blot检测显示Caspase-9蛋白表达明显减少(t=3.11,t=5.62;P<0.05,P<0.01)。结论 BMP-7能减轻缺血再灌注损伤脑组织损伤程度,其机制可能与下调线粒体凋亡途径中Caspase-9的表达有关,而且保护作用与剂量呈正相关。     

PPAPγ和缺血再灌注脑组织损伤关系的研究

目的明确实验性缺血再灌注脑组织PPAPγmRNA和蛋白的表达变化,结合相关文献分析PPAPγ和缺血再灌注脑组织损伤的关系。方法建立SD大鼠MCAO缺血90min再灌注模型。实验分为对照组、假手术组和缺血再灌注组。缺血再灌注组取缺血后12h、24h和48h3个时间点进行观察。用RT-PCR方法及Western blotting方法分别检测PPARγmRNA和蛋白的表达。结果脑缺血再灌注组PPARγmRNA和蛋白表达较正常对照组和假手术组明显降低。通过对缺血后12h、24h和48h3个时间点的动态变化观察显示,缺血后12h表达最低,并且随缺血后时间的推移,其表达逐渐增加,存在显著性差异。但缺血后48h的表达值仍低于正常对照组和假手术组。结论缺血再灌注脑组织PPARγ表达下调可能通过炎性机制参与了脑缺血病理损伤,提示针对PPARγ作为一靶点进行干预可能对于缺血性脑血管病的治疗是一个新的研究方向。     

PPARγ激活剂对大鼠缺血再灌注脑组织的保护作用及对PPARγ表达的影响

目的 明确不同剂量的PPARγ激活剂对缺血再灌注脑组织损伤的保护作用及对PPARγ表达变化的影响.方法 健康雄性SD大鼠分为假手术组、生理盐水干预组、小剂量吡格列酮（PPARγ激活剂）干预组、大剂量吡格列酮干预组.MCAO前3d分别给予吡咯列酮,每日一次灌胃给药.剂量分别是：小剂量组为10mg/kg·d,大剂量组为15mg/kg·d;生理盐水干预组仅给予等量生理盐水;假手术组亦给予等量生理盐水.以缺血后24h作为观察时间点,对各指标进行比较分析.TTC染色测定脑梗死体积,RT-PCR和Western blotting方法分别检测PPARγmRNA和蛋白的表达.结果 PPARγ激活剂可以明显降低脑梗死体积,并且大剂量干预组较小剂量干预组效果显著;两种不同剂量的PPARγ激活剂对动物的血糖、血脂、胰岛素水平及血压变化无影响;PPARγ激活剂可以促进PPARγ mRNA和蛋白表达的增加,并且呈现出随吡格列酮剂量的增加而增高的趋势.结论 PPARγ激活剂可以促进缺血再灌注脑组织PPARγ mRNA和蛋白的表达,并且当干预剂量增加的同时,伴随着PPARγ表达的进一步增加,其所呈现出的对缺血脑组织的保护作用也进一步增强,以上提示将PPARγ作为一靶点,利用其激活剂对其进行干预可以对缺血再灌注脑组织产生保护作用.     

美卡素对急性脑缺血再灌注大鼠海马CA1区PPARγ的影响

目的探讨美卡素对急性脑缺血再灌注损伤大鼠的脑保护作用。方法将72只雄性SD大鼠分为4组:A组(正常组)、B组(假手术组)、C组(模型组)、D组(干预组)。大鼠大脑中动脉缺血再灌注(MCAO)模型利用改良Zea Longa线栓法制备,免疫组化染色检测PPARγ表达变化,采用Zea Longa 5分制标准进行大鼠神经行为学评分。结果 A、B组海马CA1区PPARγ均有表达,神经行为学评分0分,差异无统计学意义(P>0.05)。C组PPARγ表达减少,神经行为学评分明显增高,与A、B组相比差异有统计学意义(P<0.05)。D组与C组相比PPARγ表达增多,神经行为学评分降低,差异有统计学意义(P<0.05)。结论美卡素可以增加急性缺血再灌注大鼠脑内PPARγ的表达,降低神经行为学评分,具有脑保护作用。     

大鼠脑缺血再灌注损伤后Cx43蛋白的表达模式

目的：建立大鼠大脑中动脉闭塞（MCAO）缺血再灌注模型,探索再灌注后Cx43蛋白的表达模式。方法75只大鼠随机分为MCAO组（60只）和假手术组（15只）。MCAO组均行MCAO手术,术后根据缺血再灌注时间分为0.5、4、12、24 h 4个亚组,每组15只;假手术组不插入线栓。各组进行改良神经损伤严重程度评分（mNSS）、脑组织TTC染色及神经元尼式染色,Western blot及免疫组织化学方法检测各组脑组织Cx43蛋白的表达并进行统计学分析。结果 MCAO组造模成功率75%。MCAO组大鼠mNSS评分明显高于假手术组（P＜0.05）,脑梗死面积增加,额顶叶皮质区神经元大量损伤。Western blot结果显示：假手术组及MCAO 0.5、4、12、24 h组Cx43表达量分别为0.23±0.12、0.58±0.18、0.78±0.07、0.61±0.05和0.27±0.07, MCAO 0.5、4、12 h组与假手术组差异均有统计学意义（P＜0.05）,而MCAO 24 h组与假手术组差异无统计学意义（P＞0.05）。免疫组化结果显示：MCAO组侧脑室下区Cx43的表达在0.5 h开始升高,4 h达高峰,12 h逐渐下降,直至24 h恢复基线水平;与Western blot结果一致。结论 Cx43蛋白在脑缺血性再灌注损伤发生、发展中起重要作用。     

rt-PA与尿激酶溶栓治疗对MMP-9和血-脑屏障通透性的影响

目的 探讨重组组织型纤溶酶原激活物和尿激酶溶栓治疗对缺血-再灌注大鼠脑组织基质金属蛋白酶-9 表达水平和血-脑屏障通透性的影响.方法 采用自体血栓塞大脑中动脉制备大脑中动脉闭塞模型,于缺血-再灌注后6 h 静脉注射重组组织型纤溶酶原激活物或尿激酶,分别检测大鼠脑组织基质金属蛋白酶-9 表达水平、血-脑屏障通透性、梗死灶体积及脑组织含水量.结果 缺血-再灌注后24 h,缺血组大鼠脑组织基质金属蛋白酶-9 表达水平(0.16 ± 0.01)、伊文蓝浓度[(5774.00 ± 1659.70)ng/g]明显升高(t = 19.687,P = 0.000;t = 15.170,P = 0.000),梗死灶体积[(32.43 ± 9.93)%]扩大(t = 7.993,P =0.000);经重组组织型纤溶酶原激活物或尿激酶溶栓治疗后,溶栓治疗组大鼠脑组织基质金属蛋白酶-9表达水平[(0.23 ± 0.03)、(0.23 ± 0.02)]进一步升高(t = 21.194,P = 0.000;t = 30.486,P = 0.000),梗死灶体积[(15.51 ± 8.80)%、(17.06 ± 9.73)%]明显缩小(t = 3.928,P = 0.011;t = 1.393,P = 0.022).其余各项参数组间差异无统计学意义(均P > 0.05).结论 重组组织型纤溶酶原激活物和尿激酶溶栓治疗可显著提高基质金属蛋白酶-9表达水平,进而导致血-脑屏障通透性增加.     

缺血预适应对局灶性脑缺血再灌注大鼠海马CA_1区血管内皮生长因子及存活素表达的影响

目的通过观察缺血预适应后局灶性脑缺血再灌注大鼠缺血侧海马CA1区血管内皮生长因子(VEGF)、存活素表达的变化,探讨缺血预适应的脑保护机制。方法 SD大鼠130只,随机分为假手术组(SO组)、脑缺血组(MCAO组)和脑缺血预适应组(BIP组),后两组按缺血后再灌注时间不同分为再灌注2 h、6 h、12 h、24 h、48 h及72 h 6个亚组。采用改良线栓法制作大鼠大脑中动脉阻塞(2 h)模型,应用免疫组化法与Western blot法观察脑缺血后再灌注各时间点海马CA1区VEGF、存活素的表达变化。结果与MCAO组比较,BIP组各时间点VEGF、存活素的阳性细胞数及蛋白量表达均明显增高,差异有统计学意义(P<0.05);两组组内各相邻时间点比较,差异有统计学意义(P<0.05)。结论脑缺血预适应可能通过上调VEGF、存活素的表达,发挥脑保护作用。     

羟基红花黄色素A对谷氨酸诱导损伤神经元过氧化物酶体增殖物激活受体γ表达的影响

目的探讨羟基红花黄色素A(HSYA)拮抗谷氨酸诱导神经元损伤的保护机制。方法采集经体外原代培养第7天的Sprague Dawley胎鼠皮质神经元,通过形态学观察、噻唑蓝法、Westernblotting法分别检测过氧化物酶体增殖物激活受体γ(PPARγ)和磷酸化PPARγ(pPPARγ,即PPARγ的失活形式)表达水平,以探讨HSYA抗谷氨酸诱导神经元损伤的保护机制。结果经谷氨酸处理后神经元发生肿胀、部分崩解、死亡。与正常对照组相比,谷氨酸不同剂量组(1.00、5.00和10.00mmol/L组)的神经元存活率(66.60%、33.40%和21.60%)和PPARγ蛋白表达水平显著降低,对照组灰度值:1.06±0.18,谷氨酸5.00和10.00mmol/L组灰度值分别为:0.32±0.09、0.28±0.07(均P=0.000),pPPARγ蛋白表达水平明显升高,灰度值分别为:0.37±0.05、1.83±0.17和1.75±0.21(均P=0.000)。HSYA与谷氨酸共同处理后神经元形态明显改善、细胞相对存活率提高,谷氨酸5.00mmol/L,HSYA0.01、0.10和1.00mmol/L组分别为33.40%、35.30%、51.00%和72.50%(P=0.742、0.033、0.002),PPARγ蛋白表达水平呈现逐渐升高趋势,对照组,谷氨酸5.00mmol/L,HSYA0.01、0.10和1.00mmol/L组灰度值分别为:1.20±0.16、0.25±0.06、0.39±0.10、0.41±0.12、0.37±0.08,但差异未达到统计学意义(均P>0.05),pPPARγ蛋白表达水平降低,对照组,谷氨酸5.00mmol/L,HSYA0.01、0.10和1.00mmol/L组灰度值分别为:0.51±0.14、1.91±0.25、1.70±0.26、1.25±0.23、0.85±0.19,(P=0.022、0.004、0.000)。结论 HSYA对由谷氨酸诱导的神经元损伤具有保护作用,其机制与抑制PPARγ蛋白磷酸化即抑制PPARγ活性有关。     

白细胞介素13受体在脑胶质瘤诊断中的应用

目的评价白细胞介素13受体(IL-13R)α2的免疫组织化学检测结果对脑胶质瘤辅助诊断的应用价值。方法收集脑胶质瘤、脑膜瘤、癫病灶组织和正常脑组织标本共103例,制作成组织芯片,分别运用免疫组织化学和原位杂交方法检测人IL-13Rα1、α2及GFAP的表达情况。结果 (1)免疫组织化学方法检测IL-13Rα1、α2在各组中的阳性率分别为:胶质母细胞瘤(5/14;6/14)、间变型星形细胞瘤(1/4;3/4)、间变型少突-星形细胞瘤(1/4;3/4)、Ⅱ级星形细胞瘤(5/15;8/15)、Ⅱ级少突-星形细胞瘤(0/3;3/3)阳性表达IL-13Rα1、α2;而在毛细胞型星形细胞瘤(0/1)、脑膜瘤(0/24)、癫病灶组织(0/19)、正常脑组织(0/1)中均无表达。(2)原位杂交方法检测IL-13Rα1、α2的表达结果与免疫组化结果基本一致(x2检验,P=0.115)。(3)免疫组织化学和原位杂交方法检测IL-13Rα1表达的阳性细胞百分比在高、低度恶性胶质瘤之间无显著性差异(IHC,P=0.566;ISH,P=0.317),IL-13Rα2表达的阳性细胞百分比在两组之间有显著性差异(P=0.041;P=0.043)。(4)免疫组化检测GFAP与IL-13Rα1、α2在脑肿瘤表达的阳性率的一致性检验,Kappa值分别为0.496和0.682。(5)IL-13Rα2免疫组化检测方法诊断星形细胞瘤的灵敏度为60.5%,特异度为100%,与病理诊断结果的一致性检验Kappa值为0.659。结论 (1)IL-13Rα1、α2主要在星形细胞来源的胶质瘤中表达。(2)IL-13Rα2在高度恶性星形细胞瘤的表达量高于低度恶性星形细胞瘤。(3)IL-13Rα2的免疫组化检测结果与原位杂交结果基本一致,且与病理诊断结果一致性较高,有可能用于胶质瘤的辅助诊断。     

Magnetic auditory evoked fields: interhemispheric asymmetry

Magnetic auditory evoked fields (MAEFs) were recorded from the right (11 subjects) and the left (7 subjects) hemisphere following 128 click stimuli delivered to contralateral, ipsilateral and both (bilateral) ears. Right hemisphere MAEFs were of higher amplitude following contralateral, compared to ipsilateral, stimulation in 9 of 11 subjects; mean contralateral response amplitude was 135 +/- 33% (S.D) of ipsilateral response amplitude. Left hemisphere MAEFs were of higher amplitude following contralateral stimulation in 7 of 7 subjects; mean contralateral response amplitude was 145 +/- 44% of ipsilateral response amplitude. These observations are compatible with evidence that a majority of centripetal auditory input is crossed, and/or that contralateral auditory stimulation activates a larger area of cortex than does ipsilateral stimulation.     

Auditory cortico-cortical connections in the owl monkey

Two tonotopically organized cortical fields, the primary (A1) and rostral (R) fields, comprise a core of auditory cortex in the owl monkey. Injections of tritiated proline were made into each of these fields to determine their projections to the auditory fields in the ipsilateral and contralateral hemispheres using autoradiographic methods. Neurons in R project to the rostromedial (RM) and primary fields in both hemispheres, and to the posterolateral (PL) and anterolateral (AL) fields in the ipsilateral hemisphere. In addition, the rostral fields in the two hemispheres are connected. Neurons in the primary field project to RM and R in both hemispheres and to AL, PL, and the caudomedial (CM) field in the ipsilateral hemisphere. The primary fields in the two hemispheres are connected. Single injections into A1 and R often result in labelingof two or more columns of tissue in the ipsilateral and contralateral target fields. Cortico-cortical axon terminations are concentrated in layer IV of fields AL and RM and in upper layer III and layer IV of R and CM. In A1, axon terminals of neurons whose cell bodies lie in A1 in the opposite hemisphere are concentrated in upper layer III and layer IV; axon terminals of neurons located in field R of the same hemispheres are concentrated in layers I and II. Layer IV of PL contains the greatest concentration of cortico-cortical axon terminals; the supragranular layers contain a somewhat lower concentration. Neurons in R project contralaterally in the anterior commissure while A1 neurons send their axons contralaterally in the corpus callosum.     

Hippocampal memory function as reflected by the intracarotid sodium methohexital Wada test

The intracarotid amobarbital procedure (IAP) determines lateralization of memory function for predicting the risk of amnesia after epilepsy surgery. Shortages of amobarbital led to its substitution with sodium methohexital in the intracarotid methohexital procedure (IMP). We compared IAP scores (32 patients) with IMP scores (20 patients). Wada ipsilateral and contralateral memory scores were analyzed and compared, as was the relationship of these scores to the results of standard neuropsychological memory tests. There was no significant difference in Wada contralateral memory scores (first injection) between the IAP and IMP. Differences between the IAP and IMP in memory scores for the hemisphere ipsilateral to the epileptogenic focus (second injection) were significant (P=0.01), patients who underwent the IMP manifesting a higher ipsilateral memory reserve. IAP scores related better to standard neuropsychological memory test scores than did IMP scores. The anesthetic drug used in Wada testing may affect lateralized memory assessment and prediction of postsurgical memory changes.     

Contralateral EEG slowing and amobarbital distribution in Wada test: an intracarotid SPECT study

PURPOSE: To relate the occurrence of contralateral electroencephalogram slowing (CES) to amobarbital distribution, we performed electroencephalogram (EEG) monitoring and intracarotid single photon emission computed tomography (SPECT) during an intracarotid amobarbital procedure (IAP). METHODS: IAP was performed on 22 patients with temporal lobe epilepsy. CES was defined as the occurrence of significant EEG slowing on the contralateral hemisphere (>50% of the ipsilateral hemisphere slowing) after amobarbital injection. To map the distribution of the amobarbital, we injected a mixture of amobarbital and (99m)technetium-ethylcysteinate dimer (99mTc-ECD) into the internal carotid artery and performed a brain SPECT 2 h later. In the SPECT images, regions of interest were determined by ipsilateral and contralateral anterior cerebral artery territories (iACA, cACA), ipsilateral and contralateral middle cerebral artery territories (iMCA, cMCA), and ipsilateral and contralateral posterior cerebral artery territories (iPCA, cPCA), as well as ipsilateral and contralateral anterior and posterior mesial temporal regions (iAMT, cAMT, iPMT, cPMT). The perfusion of amobarbital was interpreted visually in each region. RESULTS: Amobarbital was distributed in the iMCA in all the patients; in the iACA in 20 (90.9%) patients; in the iAMT in 14 (63.5%); and in the iPCA and iPMT in only two (9.1%). CES was observed in 13 (59.1%) patients. Cross-perfusion of amobarbital in limited areas of the cACA were observed in only four of 13 patients. Wada retention memory scores (WRMS) showed no significant difference between the CES- (n = 9) and CES+ (n = 13) groups. CONCLUSIONS: Amobarbital rarely perfused the iPCA territory and the iPMT region and was rarely delivered to the contralateral hemisphere. The occurrence of CES was not related to the cross-perfusion of amobarbital. CES appears to be produced by a transient functional disconnection from the ipsilateral hemisphere.     

Ipsilateral and contralateral SEP components following median nerve stimulation: effects of interfering stimuli applied to the contralateral hand

Somatosensory evoked potentials (SEPs) recorded over the hemisphere ipsilateral and contralateral to the electrically stimulated median nerve were analysed in the presence or absence of interfering movement, tactile and vibratory activity in the contralateral hand. In the control wave forms the early potentials recorded over the ipsilateral frontal region, P19 and N25, showed apparent phase reversal with N19 and P25 respectively in the contralateral parietal region and were therefore considered to be produced by the same generator in the primary sensory cortex. All other potentials recorded over the ipsilateral hemisphere were of the same polarity and similar latency to potentials present contralaterally, and their amplitude diminished progressively with distance from the contralateral hemisphere. They were therefore believed to be volume-conducted from the contralateral hemisphere, rather than originating in the ipsilateral hemisphere through uncrossed ascending pathways or interhemispheric connections. The distribution of effects produced by interfering activity in the contralateral hand was demonstrated by subtracting the 'interference' from the 'control' response to derive a 'difference' wave form. Difference potentials present over the contralateral scalp were consistent with influence on generators in the contralateral hemisphere. In particular, voluntary movement of the contralateral hand resulted in difference potentials distributed in accordance with a proposed generator in area 3a or 4. No consistent difference potentials were found in the ipsilateral parietal region. In the ipsilateral frontal region, however, an upward potential whose latency was around 55 msec was proposed to be due to a generator in the supplementary motor area of the contralateral hemisphere.