2,061 research outputs found

    Electron Microscopic Demonstration of Neural Connections Using Horseradish Peroxidase: A Comparison of the Tetramethylbenzidine Procedure With Seven Other Histochemical Methods

    Get PDF
    Eight methods for the electron microscopic demonstration of horseradish peroxidase (HRP) labeling have been compared in adjacent series of vibratome sections of mouse lumbar spinal cord. The tracer, a HRP-wheat germ agglutinin (WGA) conjugate, was injected into the gastrocnemius muscle complex. Following retrograde axonal transport to the lumbar motor neurons and transganglionic anterograde transport of the tracer to the dorsal horn, the HRP activity was demonstrated in eight series of adjacent sections of lumbar spinal cord using eight methods. These included procedures using tetramethylbenzidine (TMB), benzidine dihydrochloride (BDHC), o-tolidine, paraphenylenediamine-pyrocatechol (PPD-PC), and 4 methods using 3,3\u27-diaminobenzidine (DAB). All eight methods were able to demonstrate both retrograde labeling of motor neurons and transganglionic anterograde transport into the dorsal horn. However, there were differences in the appearance of the various reaction products under the electron microscope. In addition, differences in the distribution of the reaction products were observed by both light and electron microscopy. The largest distribution of reaction product was observed with TMB. BDHC and o-tolidine were next, followed by the DAB procedures and PPD-PC. The TMB, BDHC, and o-tolidine reaction products were all found to be suitable for electron microscopy. The TMB reaction product was electron dense and had a very distinctive crystalloid appearance that made identification of HRP-labeled neuronal profiles easy and unequivocal. Copyright © 1982 by The Histochemical Society, Inc

    Right Hemisphere Partial Complex Seizures: Mania, Hallucinations, and Speech Disturbances During Ictal Events

    Full text link
    A patient with right hemisphere complex partial seizures exhibited extreme emotional lability resembling mania, neologisms resembling those found in fluent aphasia, and hallucinations during ictal periods. The electroencephalographic and clinical findings in this case suggest that cortical and subcortical structures of the right hemisphere may play a role in mediating the expression of language content. RÉSUMÉ Chez un patient prÉsentant des crises partielles complexes de l'hÉmisphÈre droit, nous avons observÉ pendant les crises une labilitÉÉmotionnelle Évoquant le diagnostic de manie. des nÉologismes ressemblant À ceux de l'aphasie de Wernicke et des hallucinations. Nos constatation EEG et cliniques suggÈrent que les structures corticales et sous-corticales de l'hÉmisphÈre droit peuvent jouer un rÔle dans la mÉdiation de l'expression du contenu linguistique. RESUMEN Un paciente con ataques parciales complejos originados en el hemisferio derecho mostrÓ una labilidad emocional extrema semejante a la mania, neologismos comparables a los que se encuentran en la afasia fluida y alucinaciones durante los perÍodos ictales. Los hallazgos clÍnicos y del EEG en este caso sugieren que estructuras corticales y subcorticales del hemisferio derecho pueden jugar un papel en la funciÓn del contenido del lenguaje expresivo.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66016/1/j.1528-1157.1988.tb05093.x.pd

    Phonological Facilitation of Object Naming in Agrammatic and Logopenic Primary Progressive Aphasia (PPA): Evidence for a Phonological Processing Deficit

    Get PDF
    Naming is a pervasive deficit in primary progressive aphasia. However, the source of such deficits across PPA variants is little understood. In this study, individuals with agrammatic (PPA-G) and logopenic (PPA-L) PPA, along with age-matched controls, performed a picture-word interference task to test for online phonological processing deficits during naming. All groups exhibited phonological facilitation (PF) effects, i.e., speeded picture naming in the presence of phonologically-related words. However, the PPA participants exhibited abnormally large PF effects that also were protracted, compared to the control group. These results suggest that impaired phonological processing may contribute to anomia in PPA-G and PPA-L

    Shifts of Effective Connectivity within a Language Network during Rhyming and Spelling

    Get PDF
    This is the published version, also available here: http://dx.doi.org/10.1523/JNEUROSCI.0864-05.2005.We used functional magnetic resonance imaging to examine task-specific modulations of effective connectivity within a left-hemisphere language network during spelling and rhyming judgments on visually presented words. We identified sites showing task-specific activations for rhyming in the lateral temporal cortex (LTC) and for spelling in the intraparietal sulcus (IPS). The inferior frontal gyrus (IFG) and fusiform gyrus were engaged by both tasks. Dynamic causal modeling showed that each task preferentially strengthened modulatory influences converging on its task-specific site (LTC for rhyming, IPS for spelling). These remarkably selective and symmetrical findings demonstrate that the nature of the behavioral task dynamically shifts the locus of integration (or convergence) to the network component specialized for that task. Furthermore, they suggest that the role of the task-selective areas is to provide a differential synthesis of incoming information rather than providing differential control signals influencing the activity of other network components. Our findings also showed that switching tasks led to changes in the target area influenced by the IFG, suggesting that the IFG may play a pivotal role in setting the cognitive context for each task. We propose that task-dependent shifts in effective connectivity are likely to be mediated through top-down modulations from the IFG to the task-selective regions in a way that differentially enhances their sensitivity to incoming word-form information
    corecore