嗅觉剥夺对成年豚鼠梨状皮质NeuN和CB表达的影响

目的观察嗅觉功能剥夺后对成年豚鼠两侧梨状皮质神经元特异性核蛋白(NeuN)、维生素D依赖性钙结合蛋白(CB)表达的影响。方法将20只豚鼠随机分成两组,通过电烙铁损伤左侧外周鼻孔区建立嗅觉功能剥夺模型,饲养3周和6周之后灌注取材,采用尼氏染色与免疫组织化学技术观察各个时间点豚鼠自身两侧梨状皮质尼氏体、NeuN和CB的表达情况。结果 3周组与6周组嗅觉未剥夺侧梨状皮质尼氏体的密度、CB~+细胞密度均显著高于剥夺侧(P0.05);3周组与6周组嗅觉未剥夺侧梨状皮质NeuN~+细胞密度低于剥夺侧,差异有统计学意义(P0.05)。结论嗅觉功能活动对成年豚鼠梨状皮质神经元的表达有重要作用。     

电烙铁损伤左侧外周鼻孔区构建单侧嗅觉剥夺模型:嗅球神经的发生和转化

背景:近年来嗅球的神经发生、转化以及成熟已成为研究热点,并且嗅觉经验和神经活动能影响嗅球神经发生,但是到目前为止关于嗅觉功能活动是否影响豚鼠嗅球的神经发生尚无报道。目的:观察单侧嗅觉功能剥夺对幼年豚鼠两侧嗅球微管聚合蛋白、维生素D依赖性钙结合蛋白和小白蛋白表达的影响。方法:将24只幼年豚鼠随机分成2组,通过电烙铁损伤左侧外周鼻孔区建立嗅觉功能剥夺模型,分别于建立嗅觉功能剥夺模型后3,6周灌注取材,应用免疫组织化学技术观察不同时间点豚鼠自身两侧嗅球微管聚合蛋白、小白蛋白和维生素D依赖性钙结合蛋白的表达情况。结果与结论:造模后3周组豚鼠嗅觉未剥夺侧嗅球表达的微管聚合蛋白、小白蛋白和维生素D依赖性钙结合蛋白数目明显高于嗅觉剥夺侧(P0.05);造模后6周组豚鼠嗅觉未剥夺侧嗅球表达的微管聚合蛋白、小白蛋白和维生素D依赖性钙结合蛋白数目明显高于嗅觉剥夺侧(P0.05)。提示豚鼠嗅觉功能活动影响神经发生和转化。     

大鼠同性别社会交往引起主嗅觉系统相关脑区pERK1/2表达变化

目的:探讨大鼠同性别社会交往行为脑内pERK1/2的表达与可能作用。方法:采用三箱室社会交往箱检测雄性大鼠同性别社会交往行为,运用免疫组织化学染色观察动物10 min社会交往行为后脑内pERK1/2的表达;采用10%硫酸锌(ZnSO4)滴鼻嗅觉剥夺后观察大鼠同性别社会交往行为以及脑pERK1/2的表达状况。结果:大鼠呈现明显的同性别社会交往偏好;社会交往后,pERK1/2在与主嗅觉系统相关的脑区(如主嗅球、内嗅皮质、梨状皮质等)以及眶额皮质、前扣带皮质等脑区表达明显增加;嗅觉剥夺后大鼠的同性别社会交往行为显著减少,pERK1/2在主嗅觉系统相关脑区表达明显下降。结论:主嗅觉系统参与了雄性大鼠同性别社会交往行为,pERK1/2表达水平变化随着社会交往行为改变而改变,提示ERK1/2信号通路可能参与大鼠同性别社会交往行为。     

Epothilone D对体外培养的BTBR小鼠皮质神经元 兴奋性突触结构的影响*

目的： 探讨微管稳定剂埃博霉素D（Epo D）对孤独症谱系障碍BTBR小鼠皮质神经元兴奋性突触结构的影 响及机制。方法： 体外培养BTBR小鼠原代大脑皮质神经元,免疫荧光法检测所培养神经元的纯度;培养至相对 成熟的BTBR小鼠皮质神经元随机分为实验组（Epo D 组）、溶剂对照组（0.1% DMSO）干预24 h,再冷处理90 min 后行微管免疫荧光染色,观察微管的形态变化;免疫印迹检测微管稳定的标志蛋白（acetyl-tubulin、α-tubulin）、 微管相关蛋白（MAP2、STOP）的表达,及兴奋性突触结构前、后膜标志蛋白（VGLUT1、PSD95）、兴奋性谷氨 酸受体相关蛋白（GluN2B、mGluR5）的表达水平。结果：与对照组相比,10 nmol/L 的Epo D 可增加BTBR小鼠 皮质神经元微管的冷稳定性及微管稳定的标志蛋白、微管相关蛋白的表达;可以增加BTBR小鼠皮质神经元兴奋 性突触结构、兴奋性谷氨酸受体相关蛋白的表达,差异均有统计学意义。结论：微管稳定剂Epo D能改善体外培 养的BTBR小鼠皮质神经元兴奋性突触结构,其机制可能与增加微管稳定性有关。     

成年小鼠嗅觉功能与嗅上皮中成熟嗅觉神经元数量的实验研究

目的　探讨成年BALB/C小鼠维持嗅觉功能所需嗅上皮中成熟嗅神经元的数量,研究小鼠嗅上皮中嗅神经元数量与小鼠嗅觉功能的相关性。  方法    用0.7%的Triton X-100灌注8~10周大小的BALB/C小鼠鼻腔以诱导小鼠嗅觉障碍,分别于灌鼻后第3,7,21,49,56天行觅食实验检测小鼠觅食行为的改变,并联合免疫荧光染色（IFC）的方法,检测小鼠嗅上皮（OE）中成熟嗅神经元（ORNs）的数量与其嗅觉功能的相关性。  结果　小鼠经Triton X-100灌注鼻腔后第3、7天,其觅食时间明显延长（F=32.04,P<0.001),Bonferroni法两两比较示第3,7天觅食时间均长于对照组及造模后第21、49、56天组,P<0.001差异有统计学意义。嗅上皮中成熟嗅神经元（ORNs）的数量亦于第3、7天为低(F=223.97, P<0.001),觅食时间与嗅上皮成熟ORNs的数量呈负相关（r=－0.757,P<0.001）。小鼠嗅觉障碍于造模后第21天左右开始恢复,此时嗅上皮中OMP（+）细胞占28.66%。  结论　小鼠嗅觉功能与其嗅上皮中成熟ORNs数量具有明显的相关性;当成年BALB/C小鼠嗅上皮中成熟ORNs数量恢复至对照组的28.66%时即可使小鼠嗅觉功能得以恢复。          

视觉刺激诱导c-Fos在弱视成年大鼠视皮质神经元表达的研究

目的： 研究光刺激诱导双眼形觉剥夺性弱视成年大鼠视皮质神经元c-Fos表达情况。方法： 缝合14 d龄SD大鼠双侧眼睑建立双眼形觉剥夺性弱视模型，无光照弱视组8只，光照弱视组8只。饲养至100 d龄时剪开眼睑，光照弱视组暴露于外界光线中0.5 h，无光照弱视组不接触光线。取材后对两组视皮质组织进行Nissle染色和c-Fos蛋白免疫组化染色，并对染色结果进行计算机图像分析。结果: 光照弱视组视皮质表达c-Fos蛋白阳性神经元显著多于无光照弱视组（P<0.05）。结论: 双眼形觉剥夺弱视成年大鼠视皮质内经光刺激诱导c-Fos表达增加，提示已过视觉发育敏感期成年大鼠的视皮质仍存留一定程度的视觉可塑性。     

A53T-α-synuclein转基因小鼠嗅觉相关神经环路的变化

目的:探讨帕金森病(PD)对小鼠嗅觉功能的影响及相关神经环路的改变。方法:应用A53T-α-synuclein转基因小鼠作为PD动物模型,嗅觉习惯化-去习惯化行为学实验记录小鼠对不同气味探索的次数,评价转基因小鼠嗅觉功能;利用重组狂犬病毒跨突触示踪技术评价嗅球神经连接。结果:与野生型组小鼠比较,转基因小鼠在嗅觉功能检测即表现为气味习惯化和去习惯化过程受损;嗅球与相关脑区的神经连接显示主嗅球投射比例相对减少,梨状皮层投射比例相对增加,其他皮层投射到嗅球的神经连接差异没有统计学意义。结论:PD影响小鼠嗅觉功能并改变其嗅觉相关神经环路。     

过表达胶质细胞神经营养因子基因转染骨髓间充质干细胞移植治疗脊髓损伤

文题释义： 胶质细胞源性神经营养因子：作为轴突再生的一种重要神经营养因子,可诱导间充质干细胞向神经样细胞分化并对中枢神经系统退行性疾病、脊髓损伤后神经功能恢复起到重要作用。 突触素：作为突触的特异性蛋白是突触形成过程中最重要的标志物,主要位于神经元胞体及轴突,可调节神经元轴突延伸,参与突触囊泡的介导转运、神经递质释放,对促进脊髓损伤后神经功能恢复起到重要作用。 背景：胶质细胞神经营养因子(glial cell line derived neurotrophic factor,GDNF)在诱导骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)体外定向分化及促进脊髓损伤大鼠神经功能恢复过程中起到重要作用。 目的：观察过表达GDNF基因的BMSCs分化情况及其促进脊髓损伤大鼠神经功能恢复的潜在分子机制。 方法：①以重组目的基因腺病毒转染BMSCs并分为Ad-GDNF-GFP转染组、Ad-GFP转染组、未转染组,免疫荧光鉴定各组细胞神经元特异性烯醇化酶及微管相关蛋白2的表达,Western blot检测各组细胞GDNF、Wnt3a、Wnt7a蛋白表达。②以改良Allen法制备大鼠脊髓损伤模型,将造模成功的45只SD大鼠随机分为3组,分别以过表达GDNF基因BMSCs(GDNF-BMSCs)、BMSCs、PBS移植至脊髓损伤局部。移植后4周采用BBB评分法评估大鼠运动功能恢复情况,苏木精-伊红染色观察脊髓形态变化,免疫组化检测损伤局部神经元特异性烯醇化酶、突触素Ⅰ及胶质纤维酸性蛋白表达,Western blot检测损伤局部Bcl-2、肿瘤坏死因子α蛋白表达。 结果与结论：①Ad-GDNF-GFP转染组BMSCs可向神经元样细胞形态转变并表达神经元特异性烯醇化酶、微管相关蛋白2;Wnt3a、Wnt7a蛋白表达量显著高于Ad-GFP转染组、未转染组;②移植后4周,GDNF-BMSCs移植组大鼠BBB评分明显提高、脊髓空洞面积显著缩小。GDNF-BMSCs移植组脊髓损伤局部胶质纤维酸性蛋白、肿瘤坏死因子α表达量显著低于BMSCs移植组及PBS移植组,而神经元特异性烯醇化酶、突触素Ⅰ及Bcl-2表达量显著高于BMSCs移植组、PBS移植组;③结果表明,Wnt信号通路参与过表达GDNF基因 BMSCs向成熟神经元分化过程,移植后通过降低脊髓损伤局部炎症反应、减少细胞凋亡及胶质瘢痕形成、促进轴突再生,提高BMSCs移植治疗脊髓损伤的疗效。 ORCID: 0000-0001-6467-730X(黄成) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

脐血干细胞移植对帕金森病大鼠旋转行为的影响

背景：目前帕金森病的临床治疗还是以药物为主,细胞移植实验也多见于骨髓间充质干细胞,脐血来源干细胞移植能否改善帕金森病的旋转行为报道较少。 目的：观察脐血间充质干细胞移植对帕金森病大鼠旋转行为的影响。 方法：帕金森病模型大鼠随机分成实验组和对照组。实验组大鼠纹状体内植入用Hoechst33258标记的第4代脐血间充质干细胞,对照组注射PBS。此后每周腹腔注射阿扑吗啡以观察大鼠的旋转行为;并在移植后3,6,9周用免疫荧光双标法检测间充质干细胞的存活、迁移情况以及胶质纤维酸性蛋白、神经元特异性烯醇化酶、酪氨酸羟化酶和突触素的表达。 结果与结论：移植脐血间充质干细胞后大鼠的旋转行为与对照组相比有明显改善(P < 0.05);间充质干细胞可在大鼠脑内存活,随时间延长迁移范围扩大,分布于纹状体、胼胝体和皮质;胶质纤维酸性蛋白、神经元特异性烯醇化酶、酪氨酸羟化酶都有表达,突触素无表达。结果可见移植脐血间充质干细胞后能明显改善帕金森病大鼠旋转行为,有望成为治疗帕金森病的种子细胞。      

微管相关蛋白2与脊髓发育和损伤的修复

背景：微管相关蛋白2作为神经元特异性标记蛋白之一,其表达活性在一定程度上反映了脊髓神经细胞增殖、分化、迁移的演变规律。 目的：综述微管相关蛋白2的分子结构、生物学功能及其在脊髓发育及损伤修复中的表达分布规律,进而为脊髓损伤后神经干细胞的移植治疗提供前期研究基础。 方法：应用计算机检索1984/2012 维普、万方数据库相关文章,检索词为“脊髓,微管相关蛋白2”。同时计算机检索1984/2012 PubMed和Springer外文电子期刊及电子图书(全文)数据库相关文章,检索词为“spinal cord,Microtubule-associated protein 2(MAP-2)”。共检索到文献325篇,最终纳入符合标准的文献27篇。 结果与结论：微管相关蛋白2不仅是神经细胞的骨架成分,更是一种活跃的功能蛋白,参与神经元的生长和损伤后的修复过程,它的表达强弱可以反映脊髓神经元的发育情况。微管相关蛋白2免疫活性下降在脊髓损伤中的作用日益受到重视,而它的高表达可能在脊髓损伤后突触结构重建及受损神经功能代偿和修复中发挥重要作用。通过检测微管相关蛋白2的含量和定位,可以用来研究人类多种神经干细胞增殖、分化、迁移规律,进而探索脊髓等中枢神经系统的发育和损伤修复状况。     

Chronic restraint stress and chronic corticosterone treatment modulate differentially the expression of molecules related to structural plasticity in the adult rat piriform cortex

Stress and stress-related hormones induce structural changes in neurons of the adult CNS. Neurons in the hippocampus, the amygdala and the prefrontal cortex undergo neurite remodeling after chronic stress. In the hippocampus some of these effects can be mimicked with chronic administration of adrenal steroids. These changes in neuronal structure may be mediated by certain molecules related to plastic events such as the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). The expression of PSA-NCAM persists in the adult hippocampus and it is up-regulated after chronic stress. The piriform cortex also displays considerable levels of PSA-NCAM during adulthood and indirect evidence suggests that it may also be the target of stress and stress related-hormones. Using immunohistochemistry we have studied the expression of PSA-NCAM and doublecortin (DCX; another protein implicated in neuronal structural plasticity) in the piriform cortex of adult rats subjected either to 21 days of chronic restraint stress or to oral corticosterone administration during the same period. Our results indicate that chronic stress and chronic corticosterone administration have differential effects on the expression of PSA-NCAM and DCX. While chronic stress increases the number of PSA-NCAM- and DCX-immunoreactive cells in the piriform cortex layer II, chronic corticosterone administration decreases these numbers. These findings indicate that stress and adrenal steroids affect the piriform cortex and suggest that in this region, as in the hippocampus, they may induce structural changes. This is a potential mechanism by which stress and corticosterone modulate functions of this limbic region, such as its participation in olfactory memory.     

Origin,migration and fate of newly generated neurons in the adult rodent piriform cortex

Newly generated neurons are continuously added to the olfactory epithelium and olfactory bulbs of adult mammals. Studies also report newly generated neurons in the piriform cortex, the primary cortical projection site of the olfactory bulbs. The current study used BrdU-injection paradigms, and in vivo and in vitro DiI tracing methods to address three fundamental issues of these cells: their origin, migratory route and fate. The results show that 1 day after a BrdU-injection, BrdU/DCX double-labeled cells appear deep to the ventricular subependyma, within the white matter. Such cells appear further ventral and caudal in the ensuing days, first appearing in the rostral piriform cortex of mice at 2 days after the BrdU-injection, and at 4 days in the rat. In the caudal piriform cortex, BrdU/DCX labeled cells first appear at 4 days after the injection in mice and 7 days in rats. The time it takes for these cells to appear in the piriform cortex and the temporal distribution pattern suggest that they migrate from outside this region. DiI tracing methods confirmed a migratory route to the piriform cortex from the ventricular subependyma. The presence of BrdU/NeuN labeled cells as early as 7 days after a BrdU injection in mice and 10 days in the rat and lasting as long as 41 days indicates that some of these cells have extended survival durations in the adult piriform cortex. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Co-localization of corticotropin-releasing hormone with glutamate decarboxylase and calcium-binding proteins in infant rat neocortical interneurons

 Corticotropin releasing hormone (CRH) has been localized to interneurons of the mammalian cerebral cortex, but these neurons have not been fully characterized. The present study determined the extent of co-localization of CRH with glutamate decarboxylase (GAD) and calcium-binding proteins in the infant rat neocortex using immunocytochemistry. CRH-immunoreactive (ir) neurons were classified into two major groups. The first group was larger and consisted of densely CRH-immunostained small bipolar cells, predominantly localized to layers II and III. The second group of CRH-ir cells was lightly labeled and included multipolar neurons mainly found in deep cortical layers. Co-localization studies indicated that the vast majority of CRH-ir neurons, including both bipolar and multipolar types, was co-immunolabeled for GAD-65 and GAD-67. Most multipolar, but only some bipolar, CRH-ir neurons also contained parvalbumin, while CRH-ir neurons rarely contained calbindin or calretinin. These results indicate that virtually all CRH-ir neurons in the rat cerebral cortex are GABAergic. Furthermore, since parvalbumin is expressed by cortical basket and chandelier cells, the colocalization of CRH and parvalbumin suggests that some cortical CRH-ir neurons may belong to these two cell types. Received: 15 April 1998 / Accepted: 16 June 1998     

Effects of cholinergic depletion on glutamic acid decarboxylase immunoreactivity in the somatosensory cortex of rats

 The purpose of these experiments was to determine the effects of cholinergic depletion on the morphology and staining density of barrels formed by glutamic acid decarboxylase-positive neuropil in the posteromedial barrel subfield of the somatosensory cortex. The density and distribution of glutamic acid decarboxylase immunoreactive neuropil were examined after highly selective lesions of cholinergic neurons in the nucleus basalis of Meynert with an immunotoxin, IgG 192-saporin. Glutamic acid decarboxylase immunoreactivity was also examined in animals subjected to a whisker-pairing experience and lesion of acetylcholine inputs from the nucleus basalis of Meynert. Seven to 9 weeks after intraventricular injection of the immunotoxin, animals were perfused with a zinc aldehyde fixative and glutamic acid decarboxylase immunoreactivity was examined in 30-μm tangential sections. Cholinergic depletion caused reduced glutamic acid decarboxylase immunoreactivity in selective regions of the posteromedial barrel subfield. The density of neuropil and cell bodies immunoreactivie for glutamic acid decarboxylase was significantly reduced in septa and perimeters of barrel walls. The length, width, and area of barrels were reduced 10–20% in cholinergic-depleted animals compared with controls. The density of glutamic acid decarboxylase immunoreactivity in the hollow of barrels was not affected by this treatment. Whisker pairing did not significantly change the density of glutamic acid decarboxylase immunoreactivity in barrels. These observations are discussed in regard to how long-term cholinergic depletion affects the function of different fiber systems in the posteromedial barrel subfield cortex and how some sensory functions may be compromised. Accepted: 3 February 1997     

Electron microscopic study of synaptogenesis and myelination of the olfactory centers in developing rats

Development of the central olfactory system was studied in the rat with an electron microscope at three main structures: the olfactory bulb, the lateral olfactory tract, and the primary olfactory cortex (the piriform cortex). As a parameter of development, the synaptic density was examined quantitatively in the bulbar glomerulus and layer Ia (termination of bulbofugal fibers) of the piriform cortex, which are the key stations of the olfactory pathway. The synaptic densities in the glomerulus and those in layer Ia were 5.7% and 4.6% on embryonic day 19, 15.8% and 12.5% on postnatal day (P) 0, and 57.3% and 37.2% on P10, as compared with the adult (100%). As another parameter of development, the density of myelinated axons in the lateral olfactory tract was examined quantitatively. The densities of myelinated axons in the tract were 0% on P5, 15.1% on P10, and 73.5% on P21 of the adult density. Maturation in the tract was still progressing, even at P21, in terms of bundle formation and the thickness of myelin sheaths. The results show that synaptogenesis in the bulbar glomerulus is followed by synaptogenesis in layer Ia of the piriform cortex, and that myelination in the lateral olfactory tract occurs over a prolonged period, even in the stages after P21.     

The Distribution of Ki‐67 and Doublecortin Immunopositive Cells in the Brains of Three Microchiropteran Species,Hipposideros fuliginosus,Triaenops persicus,and Asellia tridens

This study uses Ki‐67 and doublecortin (DCX) immunohistochemistry to delineate potential neurogenic zones, migratory pathways, and terminal fields associated with adult neurogenesis in the brains of three microchiropterans. As with most mammals studied to date, the canonical subgranular and subventricular neurogenic zones were observed. Distinct labeling of newly born cells and immature neurons within the dentate gyrus of the hippocampus was observed in all species. A distinct rostral migratory stream (RMS) that appears to split around the medial aspect of the caudate nucleus was observed. These two rostral stream divisions appear to merge at the rostroventral corner of the caudate nucleus to turn and enter the olfactory bulb, where a large terminal field of immature neurons was observed. DCX immunolabeled neurons were observed mostly in the rostral neocortex, but a potential migratory stream to the neocortex was not identified. A broad swathe of newly born cells and immature neurons was found between the caudoventral division of the RMS and the piriform cortex. In addition, occasional immature neurons were observed in the amygdala and DCX‐immunopositive axons were observed in the anterior commissure. While the majority of these features have been found in several mammal species, the large number of DCX immunolabeled cells found between the RMS and the piriform cortex and the presence of DCX immunostained axons in the anterior commissure are features only observed in microchiropterans and insectivores to date. In the diphyletic scenario of chiropteran evolution, these observations align the microchiropterans with the insectivores. Anat Rec, 299:1548–1560, 2016. © 2016 Wiley Periodicals, Inc.     

Expression of highly polysialylated NCAM in the neocortex and piriform cortex of the developing and the adult rat

Summary The expression of a highly polysialylated form of the neural cell adhesion molecule (NCAM-H) has been investigated in the neocortex and piriform cortex of the developing and the adult rat by using a monoclonal antibody 12E3, which has been found to recognize the polysialic acid portion of NCAM-H. Immunoblot analysis of the cortical homogenates showed that NCAM-H was temporarily expressed during the late embryonic and early postnatal stages. Further, immunohistochemical observations revealed that NCAM-H appeared at embryonic day 13 (E13) in the plexiform primordium in horizontally-oriented cells, probably Cajal-Retzius cells, which are the first neurons to differentiate. During the late embryonic stage, the marginal zone, subplate, and intermediate zone strongly stained, whereas the ventricular zone stained weakly. After birth, the NCAM-H expression was progressively attenuated from a week onwards, and almost vanished in the adult neocortex. In the primordium of the piriform cortex, NCAM-H immunoreactivity also became positive at E13. The time sequences of the NCAM-H expression in these neurons were similar to those of the neurons in the neocortical area. In the piriform cortex, however, the expression remained in a number of neurons in the layer II, which receives a large number of olfactory fibers from the olfactory bulb, where prolonged neurogenesis and construction of neural circuits take place in adulthood. These results suggest that NCAM-H not only plays an important role in the developing rat cortex, but also may be involved in some functions related to reorganization in the adult piriform cortex.     

Plasticity in the barrel cortex of the adult mouse: transient increase of GAD-immunoreactivity following sensory stimulation

Summary Sensory experience during perinatal life and adulthood modifies physiological and anatomical characteristics of the central nervous system. So far, this phenomenon has been studied in situations of complete or partial sensory deprivation. We here report that increased sensory stimulation, during four days, of a number of whisker follicles on the face of the adult mouse results in an increased immunoreactivity of glutamic acid decarboxylase (the biosynthetic enzyme of the inhibitory neurotransmitter GABA) in the somatosensory cortex of the adult mouse. Effects were limited to a column of tissue corresponding to the representation of the stimulated follicles and lasted two days beyond stimulation. These findings suggest that sensory stimulation transiently modifies local cortical processing.