RESUMEN
Neuroimaging studies of autism spectrum disorder (ASD) have been predominantly unimodal. While many fMRI studies have reported atypical activity patterns for diverse tasks, the MEG literature in ASD remains comparatively small. Our group recently reported atypically increased event-related theta power in individuals with ASD during lexicosemantic processing. The current multimodal study examined the relationship between fMRI BOLD signal and anatomically-constrained MEG (aMEG) theta power. Thirty-three adolescents with ASD and 23 typically developing (TD) peers took part in both fMRI and MEG scans, during which they distinguished between standard words (SW), animal words (AW), and pseudowords (PW). Regions-of-interest (ROIs) were derived based on task effects detected in BOLD signal and aMEG theta power. BOLD signal and theta power were extracted for each ROI and word condition. Compared to TD participants, increased theta power in the ASD group was found across several time windows and regions including left fusiform and inferior frontal, as well as right angular and anterior cingulate gyri, whereas BOLD signal was significantly increased in the ASD group only in right anterior cingulate gyrus. No significant correlations were observed between BOLD signal and theta power. Findings suggest that the common interpretation of increases in BOLD signal and theta power as 'activation' require careful differentiation, as these reflect largely distinct aspects of regional brain activity. Some group differences in dynamic neural processing detected with aMEG that are likely relevant for lexical processing may be obscured by the hemodynamic signal source and low temporal resolution of fMRI.
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Application of a kurtosis correction to frequency-weighted sound exposure level (SEL) improved predictions of risk of hearing damage in humans and terrestrial mammals for sound exposures with different degrees of impulsiveness. To assess whether kurtosis corrections may lead to improved predictions for marine mammals, corrections were applied to temporary threshold shift (TTS) growth measurements for harbor porpoises (Phocoena phocoena) exposed to different sounds. Kurtosis-corrected frequency-weighted SEL predicted accurately the growth of low levels of TTS (TTS1-4 < 10 dB) for intermittent sounds with short (1-13 s) silence intervals but was not consistent with frequency-weighted SEL data for continuous sound exposures.
Asunto(s)
Phocoena , Estimulación Acústica , Animales , Fatiga Auditiva , Umbral Auditivo , Audición , Humanos , Ruido/efectos adversosRESUMEN
Resting state fMRI (rsfMRI) is frequently used to study brain function, including in clinical populations. Similarity of blood-oxygen-level-dependent (BOLD) fluctuations during rsfMRI between brain regions is thought to reflect intrinsic functional connectivity (FC), potentially due to history of coactivation. To quantify similarity, studies have almost exclusively relied on Pearson correlation, which assumes linearity and can therefore underestimate FC if the hemodynamic response function differs regionally or there is BOLD signal lag between timeseries. Here we show in three cohorts of children, adolescents and adults, with and without autism spectrum disorders (ASDs), that measuring the similarity of BOLD signal fluctuations using non-linear dynamic time warping (DTW) is more robust to global signal regression (GSR), has higher test-retest reliability and is more sensitive to task-related changes in FC. Additionally, when comparing FC between individuals with ASDs and typical controls, more group differences are detected using DTW. DTW estimates are also more related to ASD symptom severity and executive function, while Pearson correlation estimates of FC are more strongly associated with respiration during rsfMRI. Together these findings suggest that non-linear methods such as DTW improve estimation of resting state FC, particularly when studying clinical populations whose hemodynamics or neurovascular coupling may be altered compared to typical controls.
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Trastorno del Espectro Autista/fisiopatología , Mapeo Encefálico/métodos , Encéfalo/fisiopatología , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética , Adolescente , Adulto , Trastorno del Espectro Autista/diagnóstico por imagen , Encéfalo/diagnóstico por imagen , Niño , Interpretación Estadística de Datos , Femenino , Humanos , Masculino , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiopatología , Dinámicas no Lineales , Adulto JovenRESUMEN
Autism spectrum disorders (ASDs) represent a formidable challenge for psychiatry and neuroscience because of their high prevalence, lifelong nature, complexity and substantial heterogeneity. Facing these obstacles requires large-scale multidisciplinary efforts. Although the field of genetics has pioneered data sharing for these reasons, neuroimaging had not kept pace. In response, we introduce the Autism Brain Imaging Data Exchange (ABIDE)-a grassroots consortium aggregating and openly sharing 1112 existing resting-state functional magnetic resonance imaging (R-fMRI) data sets with corresponding structural MRI and phenotypic information from 539 individuals with ASDs and 573 age-matched typical controls (TCs; 7-64 years) (http://fcon_1000.projects.nitrc.org/indi/abide/). Here, we present this resource and demonstrate its suitability for advancing knowledge of ASD neurobiology based on analyses of 360 male subjects with ASDs and 403 male age-matched TCs. We focused on whole-brain intrinsic functional connectivity and also survey a range of voxel-wise measures of intrinsic functional brain architecture. Whole-brain analyses reconciled seemingly disparate themes of both hypo- and hyperconnectivity in the ASD literature; both were detected, although hypoconnectivity dominated, particularly for corticocortical and interhemispheric functional connectivity. Exploratory analyses using an array of regional metrics of intrinsic brain function converged on common loci of dysfunction in ASDs (mid- and posterior insula and posterior cingulate cortex), and highlighted less commonly explored regions such as the thalamus. The survey of the ABIDE R-fMRI data sets provides unprecedented demonstrations of both replication and novel discovery. By pooling multiple international data sets, ABIDE is expected to accelerate the pace of discovery setting the stage for the next generation of ASD studies.
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Mapeo Encefálico , Encéfalo/patología , Encéfalo/fisiopatología , Trastornos Generalizados del Desarrollo Infantil/patología , Trastornos Generalizados del Desarrollo Infantil/fisiopatología , Neuroimagen , Adolescente , Adulto , Niño , Conectoma , Humanos , Difusión de la Información , Internet , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Vías Nerviosas/patología , Vías Nerviosas/fisiopatología , Fenotipo , Procesamiento de Señales Asistido por Computador , Adulto JovenRESUMEN
BACKGROUND: Sexually transmitted human papillomavirus (HPV) high-risk types cause carcinoma and low-risk types lead to warts of genitoanal area. Since the HPV vaccine has been introduced, awareness of HPV infection, prevention and health-related behaviour have not been studied in a large sample of young women in Germany. OBJECTIVES: Assessment of awareness and health-related behaviour regarding HPV infection and prevention among young German females. METHODS: In 2010, a postal cross-sectional survey was conducted with a random representative sample size (n = 2000) of females aged 19-35 attending Germany's largest (comprehensive) university, which was designed to obtain data about socio-demographics, the awareness of sexually transmitted HPV, genitoanal neoplasms and their prevention, HPV vaccine, immunisation and cervical cancer screening. RESULTS: Of the 547 (27.3%) participants, 69.1% had heard of HPV, 62.5% were aware of the vaccine, 14.4% were vaccinated and 6.9% reported a history of sexually transmitted infection, including HPV (2.7%). The HPV-related knowledge among those who had heard of it was high (75.1-99.7%), except of that HPV affects men (52.9%) and HPV's causative role in genital (54.2%) and anal (35.6%) warts, and smoking (11.3%) as an HPV risk factor. The lower HPV knowledge score (Asunto(s)
Condiloma Acuminado/prevención & control
, Conocimientos, Actitudes y Práctica en Salud
, Infecciones por Papillomavirus/prevención & control
, Vacunas contra Papillomavirus/administración & dosificación
, Neoplasias del Cuello Uterino/prevención & control
, Adulto
, Enfermedades del Ano/prevención & control
, Enfermedades del Ano/psicología
, Concienciación
, Condiloma Acuminado/psicología
, Femenino
, Enfermedades de los Genitales Femeninos/prevención & control
, Enfermedades de los Genitales Femeninos/psicología
, Alemania
, Vacuna Tetravalente Recombinante contra el Virus del Papiloma Humano Tipos 6, 11 , 16, 18
, Humanos
, Infecciones por Papillomavirus/psicología
, Enfermedades Virales de Transmisión Sexual/prevención & control
, Enfermedades Virales de Transmisión Sexual/psicología
, Neoplasias del Cuello Uterino/psicología
, Adulto Joven
RESUMEN
Anaerobic ammonia oxidation (Anammox) has been identified as a new general process-strategy for nitrogen removal in wastewater treatment. In order to evaluate the role and effects of the Anammox process in wetlands, laboratory-scale model experiments were performed with planted fixed bed reactors. A reactor (planted with Juncus effusus) was fed with synthetic wastewater containing 150-200 mg L(-1) NH4+ and 75-480 mg L(-1) NO2(-). Under these operating conditions, the plants were affected by the high ammonia and nitrite concentrations and the nitrogen removal rate fell within the same range of 45-49 mg N d(-1) (equivalent to 0.64-0.70 g Nm(-2)d(-1)) as already reported by other authors. In order to stimulate the rate of nitrogen conversion, the planted reactor was inoculated with Anammox biomass. As a result, the rate of nitrogen removal was increased 4-5-fold and the toxic effects on the plants also disappeared. The results show that, in principle, subsurface flow wetlands can also function as an "Anammox bioreactor". However, the design of a complete process for the treatment of waters with a high ammonia load and, in particular, the realisation of simple technical solutions for partial nitrification have still to be developed.
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Amoníaco/metabolismo , Anaerobiosis , Biodegradación Ambiental , Nitrógeno/aislamiento & purificación , Purificación del Agua/métodos , Humedales , Biomasa , Reactores Biológicos , Oxidación-Reducción , Investigación , Eliminación de Residuos Líquidos/métodosRESUMEN
During late June and early July of 2005, signs of bermudagrass ergot were reported from numerous northern and eastern counties in Oklahoma. Signs were observed primarily on forage-type bermudagrass (Cynodon dactylon (L.) Pers.), as well as bermudagrass turf. During the "honeydew" stage, honeydew was frequently observed exuding from most of the ovaries of infected inflorescences. These signs of ergot have been observed previously on bermudagrass in Oklahoma and Texas (1). Sphacelia-type conidia were abundantly produced during the honeydew stage and were single-celled, hyaline, averaged 14 × 5 µm in size, and were reniform to allantoid in shape. When streaked on water agar, conidia produced terminal holoblastic secondary conidia. Single-spore cultures were isolated from the honeydew of bermudagrasses from Logan and Muskogee counties in Oklahoma and grew slowly as white mycelium on potato dextrose agar (PDA). Koch's postulates were fulfilled for these two isolates by spray inoculating four bermudagrass inflorescences at anthesis with mycelium scraped from a PDA plate and homogenized in water. Control plants' inflorescences were sprayed with a water suspension of a similar amount of sterile PDA as inoculated plants. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 22°C (14-h photoperiod) and 20°C (10 h of darkness). After 9 days, honeydew exuded from the inoculated inflorescences, but not from the controls. Single-spore cultures were reisolated from the honeydew, and conidia streaked on water agar formed identical secondary conidia. The complete nuclear ribosomal internal transcribed spacer (ITS) region was amplified from DNA extracted from honeydew and single-spore cultures using the ITS4 and ITS5 primers (4) and sequenced. All sequences were identical and a search of GenBank at NCBI found these sequences were most similar to the ITS regions of Claviceps cynodontis Langdon (100%, Accession No. AJ557074) and C. maximensis Theis (99%, Accession No. AJ133396). The ITS sequence from the Logan County isolate was deposited at Gen-Bank (Accession DQ187312). The morphology, secondary conidiation, and ITS sequences identify the causal fungus as C. cynodontis (2) and differentiate it from C. purpurea (Fr.) Tul., the previously identified cause of bermudagrass ergot (1). To our knowledge, this is the first report of C. cynodontis on bermudagrass in Oklahoma and may represent a recent introduction to the United States (2; S. Pazoutová and M. Flieger, personal communication). A Claviceps sp. isolated from bermudagrass has been shown to produce ergot alkaloids possibly causing "bermudagrass tremors" in cattle (3). In regions where bermudagrass is the predominant forage for livestock, the toxicological significance of bermudagrass ergot caused by C. cynodontis is unclear and requires further research. References: (1) K. E. Conway et al. Plant Dis. 76:1077, 1992. (2) S. Pazoutová et al. Can J. Plant Pathol. 27:541, 2005. (3) J. K. Porter et al. J. Agric. Food Chem. 22:838, 1974. (4) T. J. White et al. Pages 315-322 in: PCR Protocols: A Guide to Methods and Applications. Academic Press Inc., New York, 1990.
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Different types of constructed wetlands in a pilot-plant system were fed with identical municipal waste water to compare the sanitisation process in two-stage systems. With combinations of a vertical and a horizontal flow filter an E. coli reduction of 5 log10 with an E. coli influent concentration of 10(7) MPN/100 ml was achieved. Using different filter materials in each stage the total performance of the two-stage system was independent from the sequence of these materials. However, using coarser filter material in the first stage makes the filter less prone to clogging and is thus the preferential option with regard to operational reliability.
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Escherichia coli/aislamiento & purificación , Aguas del Alcantarillado/microbiología , Eliminación de Residuos Líquidos/métodos , Biodegradación Ambiental , Ecosistema , Filtración , Saneamiento , Movimientos del AguaRESUMEN
Constructed wetlands are a natural alternative to technical methods of wastewater treatment. However, our understanding of the complex processes caused by the plants, microorganisms, soil matrix and substances in the wastewater, and how they all interact with each other, is still rather incomplete. In this article, a closer look will be taken at the mechanisms of both plants in constructed wetlands and the microorganisms in the root zone which come into play when they remove contaminants from wastewater. The supply of oxygen plays a crucial role in the activity and type of metabolism performed by microorganisms in the root zone. Plants' involvement in the input of oxygen into the root zone, in the uptake of nutrients and in the direct degradation of pollutants as well as the role of microorganisms are all examined in more detail. The ways in which these processes act to treat wastewater are dealt with in the following order: Technological aspects; The effect of root growth on the soil matrix; Gas transport in helophytes and the release of oxygen into the rhizosphere; The uptake of inorganic compounds by plants; The uptake of organic pollutants by plants and their metabolism; The release of carbon compounds by plants; Factors affecting the elimination of pathogenic germs.
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Ecosistema , Plantas/metabolismo , Plantas/microbiología , Microbiología del Agua , Contaminantes Químicos del Agua/metabolismo , Purificación del Agua/métodos , Biodegradación Ambiental , Residuos Industriales/prevención & control , Oxígeno/metabolismo , Raíces de Plantas/metabolismo , Raíces de Plantas/microbiología , Microbiología del SueloRESUMEN
Processing the human face is at the focal point of most social interactions, yet this simple perceptual task is difficult for individuals with autism, a population that spends limited amounts of time engaged in face-to-face eye contact or social interactions in general. Thus, the study of face processing in autism is not only important because it may be integral to understanding the social deficits of this disorder, but also, because it provides a unique opportunity to study experiential factors related to the functional specialization of normal face processing. In short, autism may be one of the only disorders where affected individuals spend reduced amounts of time engaged in face processing from birth. Using functional MRI, haemodynamic responses during a face perception task were compared between adults with autism and normal control subjects. Four regions of interest (ROIs), the fusiform gyrus (FG), inferior temporal gyrus, middle temporal gyrus and amygdala were manually traced on non-spatially normalized images and the percentage ROI active was calculated for each subject. Analyses in Talairach space were also performed. Overall results revealed either abnormally weak or no activation in FG in autistic patients, as well as significantly reduced activation in the inferior occipital gyrus, superior temporal sulcus and amygdala. Anatomical abnormalities, in contrast, were present only in the amygdala in autistic patients, whose mean volume was significantly reduced as compared with normals. Reaction time and accuracy measures were not different between groups. Thus, while autistic subjects could perform the face perception task, none of the regions supporting face processing in normals were found to be significantly active in the autistic subjects. Instead, in every autistic patient, faces maximally activated aberrant and individual-specific neural sites (e.g. frontal cortex, primary visual cortex, etc.), which was in contrast to the 100% consistency of maximal activation within the traditional fusiform face area (FFA) for every normal subject. It appears that, as compared with normal individuals, autistic individuals 'see' faces utilizing different neural systems, with each patient doing so via a unique neural circuitry. Such a pattern of individual-specific, scattered activation seen in autistic patients in contrast to the highly consistent FG activation seen in normals, suggests that experiential factors do indeed play a role in the normal development of the FFA.
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Amígdala del Cerebelo/fisiopatología , Trastorno Autístico/fisiopatología , Mapeo Encefálico/métodos , Corteza Cerebral/fisiopatología , Cara , Percepción Visual/fisiología , Adulto , Trastorno Autístico/psicología , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Tiempo de Reacción/fisiologíaRESUMEN
BACKGROUND: Early neurodevelopmental pathogenesis in autism potentially affects emerging functional maps, but little imaging evidence is available. METHODS: We studied eight male autistic and eight matched normal subjects, using functional magnetic resonance imaging during visually paced finger movement, compared to a control condition (visual stimulation in the absence of motor response). RESULTS: Groupwise analyses showed activation in contralateral perirolandic cortex, basal ganglia, and thalamus, bilateral supplementary motor area, and ipsilateral cerebellum for both groups. However, activations were less pronounced in the autism group. Direct group comparisons demonstrated greater activation in perirolandic and supplementary motor areas in the control group and greater activation (or reduced deactivation) in posterior and prefrontal cortices in the autism group. Intraindividual analyses further showed that strongest activations were consistently located along the contralateral central sulcus in control subjects but occurred in locations differing from individual to individual in the autism group. CONCLUSIONS: Our findings, though based on a rather small sample, suggest abnormal individual variability of functional maps and less distinct regional activation/deactivation patterns in autism. The observations may relate to known motor impairments in autism and are compatible with the general hypothesis of disturbances of functional differentiation in the autistic cerebrum.
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Trastorno Autístico/patología , Trastorno Autístico/fisiopatología , Imagen por Resonancia Magnética , Corteza Motora/patología , Corteza Motora/fisiopatología , Adolescente , Adulto , Mapeo Encefálico , Humanos , MasculinoRESUMEN
Although several studies exist which have examined static functional neuroimaging following traumatic brain injury (TBI), controlled cognitive activation studies of episodic memory in this population have not been published. The present investigation studied verbal recall using [O-15]-water positron emission tomography (PET) in 5 individuals who sustained severe TBI (M GCS=6.8; M years post-injury=3.18), and 4 non-injured control participants. Statistical image analysis demonstrated changes in frontoparietal regional cerebral blood flow (rCBF) in both groups, but there were interesting differences between groups and across conditions. Frontal lobe rCBF changes in TBI patients were reduced during free recall but enhanced during recognition, when compared to controls. Changes in cerebellar rCBF were observed in the control group during free recall, but not in the TBI sample. In both groups, bifrontal rCBF increases were noted on recognition tasks. The present findings provide evidence of alterations in specific substrates involved in verbal recall following brain injury.
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Lesiones Encefálicas/diagnóstico por imagen , Lesiones Encefálicas/psicología , Encéfalo/metabolismo , Recuerdo Mental , Reconocimiento en Psicología , Tomografía Computarizada de Emisión , Aprendizaje Verbal , Adulto , Encéfalo/irrigación sanguínea , Encéfalo/diagnóstico por imagen , Lesiones Encefálicas/metabolismo , Estudios de Casos y Controles , Señales (Psicología) , Femenino , Humanos , Masculino , Radioisótopos de Oxígeno , Tomografía Computarizada de Emisión/métodosRESUMEN
The left inferior frontal lobe has been traditionally viewed as a "language area," although its involvement in the discrimination of rapid nonverbal frequency changes has been also shown. Using functional MRI, we studied seven healthy adults during discrimination of relatively slow (200 ms) tonal frequency glides. Compared to a control task, in which subjects indiscriminately responded to white noise bursts, tonal discrimination was associated with bilateral superior and middle temporal and medial frontal activations. Inferior frontal activations were bilateral, but stronger on the left. Contrary to previous studies comparing discrimination of slow frequency changes to rest, our results suggest that such discriminations-when compared to an auditory control task-activate the left inferior frontal gyrus. Our findings are consistent with a participation of Broca's area in nonlinguistic processes besides its known roles in semantic, syntactic, and phonological functions.
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Afasia de Broca/fisiopatología , Lóbulo Frontal/patología , Lóbulo Frontal/fisiopatología , Adulto , Femenino , Lateralidad Funcional/fisiología , Humanos , Imagen por Resonancia Magnética , MasculinoRESUMEN
According to the Milankovitch theory, changes in the incident solar radiation, called insolation, in the Northern Hemisphere provide the driving force for global glacial cycles. In their Perspective, Karner and Muller discuss recent studies of corals from around the world that shed doubt on the applicability of the theory to the termination of the penultimate glaciation. The authors argue that a fresh, unbiased look at the data is warranted.
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Encéfalo/fisiopatología , Encéfalo/cirugía , Epilepsia/fisiopatología , Epilepsia/cirugía , Plasticidad Neuronal , Envejecimiento/metabolismo , Envejecimiento/fisiología , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Mapeo Encefálico , Glucosa/metabolismo , Humanos , Movimiento/fisiología , Tomografía Computarizada de Emisión , Conducta Verbal/fisiologíaRESUMEN
PURPOSE: Intermittent photic stimulation (IPS) is an activation procedure used during electroencephalogram (EEG) recording to elicit paroxysmal discharges in individuals with photosensitivity. Specific responses on EEG recording may be provoked by IPS at different frequencies of flickering in normal individuals and in patients with photosensitive epilepsy. METHODS: Changes in regional cerebral blood flow (rCBF) were studied during IPS in two groups of subjects by using [15O]-water positron emission tomography (PET): a control group consisting of eight healthy adults with photic driving response during IPS on EEG recording (mean age, 25 +/- 10.5 years) without history of neurologic or psychiatric abnormalities and a patient group consisting of four adults (mean age, 33 +/- 7.5 years) with history of photosensitive epilepsy. [15O]-water PET scanning with concomitant EEG monitoring was performed during baseline and IPS at 4-, 14-, and 30-Hz frequencies. RESULTS: The control group showed photic driving response at 14-Hz IPS frequency. The patient group showed photoparoxysmal response at 14 and 30 Hz, but not at 4 Hz. Changes in rCBF were determined by means of statistical parametric mapping. Increases in rCBF in occipital cortex (Brodmann's areas 17, 18, and 19) were observed in both groups. In addition, during photic driving responses, the control group showed rCBF increases in the insula and in the thalamus, on the right side. The patient group showed a significant rCBF increase in the hypothalamic region inferior to the left caudate nucleus during photoparoxysmal response. This activation was not found in the control group. Increased rCBF also was observed in the patient group in the head of the left caudate nucleus, in the left hippocampus, and in left insula during IPS without photoparoxysmal response. No activations in these regions were observed during photoparoxysmal response. CONCLUSIONS: These data may indicate involvement of the hypothalamus in photosensitive epilepsy and may suggest a modulatory function of the caudate nucleus, which might be associated with an inhibition of epileptic discharges during IPS in patients with photosensitive epilepsy.
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Encéfalo/fisiología , Epilepsia/diagnóstico , Radioisótopos de Oxígeno , Estimulación Luminosa , Tomografía Computarizada de Emisión , Agua , Adulto , Encéfalo/irrigación sanguínea , Encéfalo/diagnóstico por imagen , Núcleo Caudado/irrigación sanguínea , Núcleo Caudado/diagnóstico por imagen , Núcleo Caudado/fisiología , Electroencefalografía/estadística & datos numéricos , Epilepsia/etiología , Femenino , Humanos , Hipotálamo/irrigación sanguínea , Hipotálamo/diagnóstico por imagen , Hipotálamo/fisiología , Masculino , Estimulación Luminosa/métodos , Flujo Sanguíneo RegionalRESUMEN
1. There is evidence for pronounced brain plasticity during postnatal maturation. The authors hypothesized that left-hemisphere lesion would be associated with greater than normal language participation of the right hemisphere and that atypical asymmetry of perisylvian language activations would be enhanced after lesion occurring in early childhood as compared to lesion occurring later in life. 2. Eleven patients with left-hemisphere lesion (aged 8-33 yrs.) and 9 normal adult comparison subjects were studied, using [15O]-water positron emission tomography. One patient group (N = 6) had early lesion onset (< or = 6 years of age), a second group (N = 5) had lesion onset later in life (> or = 10 years of age). Regional cerebral blood flow (rCBF) changes during listening to sentences (minus rest) and sentence generation (minus repetition) were compared between groups in predefined regions of interest. 3. Variance of regional activations within early and late lesion onset groups was considerable and qualitative inspection revealed only few robust group differences. However, when 4 patient pairs were approximately matched for chronological age, lesion site and VIQ, significantly reduced leftward asymmetry of activations in early lesion patients was found in the prefrontal, inferior frontal, and inferior parietal regions for expressive language, with concordant and marginally significant trends in the inferior frontal and superior temporal regions for receptive language. 4. The results suggest enhanced postlesional plasticity in childhood, while also reflecting strong individual variability probably due to clinical and demographic factors beside lesion onset.
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Encefalopatías/fisiopatología , Encéfalo/irrigación sanguínea , Encéfalo/diagnóstico por imagen , Epilepsia/fisiopatología , Adolescente , Adulto , Edad de Inicio , Encéfalo/patología , Encefalopatías/diagnóstico por imagen , Encefalopatías/patología , Niño , Epilepsia/diagnóstico por imagen , Epilepsia/patología , Femenino , Fluorodesoxiglucosa F18 , Lateralidad Funcional , Humanos , Imagen por Resonancia Magnética , Masculino , Plasticidad Neuronal , Radioisótopos de Oxígeno , Radiofármacos , Valores de Referencia , Flujo Sanguíneo Regional , Tomografía Computarizada de Emisión/métodosRESUMEN
Functional neuroimaging studies have shown enhanced right-hemisphere language activations in adults with left-hemisphere damage. We hypothesized that this effect would be stronger in patients with lesion occurring early in development. Using [15O]-water PET, we studied eight normal adults and 23 patients with unilateral left lesion during rest, listening to sentences, and sentence repetition. Thirteen patients had lesions with early onset (< 5 years) and ten had lesions with late onset (> 20 years). For listening to sentences, frontotemporal blood flow increases were significantly stronger in the left than in the right hemisphere in normal adults. This normal asymmetry was reduced in patients with late lesion and reversed in those with early lesion. For sentence repetition, analogous group differences were significant for the basal ganglia, but failed to reach significance for the (pre)motor and insular regions. We conclude that left lesion leads to alterations in the asymmetry of language activations (in and beyond the perisylvian areas). In addition, rightward shifts of language activation tend to be stronger as a consequence of early (as compared to late) lesion. Finally, postlesional reorganization appears to reflect a coexistence of 'additive' and 'subtractive' effects, i.e., activation in some regions that are not normally involved in language processing and lack of activation in other (undamaged) regions that are normally activated by language tasks.