RESUMO
Sensory information is processed in specific brain regions, and shared between the cerebral hemispheres by axons that cross the midline through the corpus callosum. However, sensory deprivation usually causes sensory losses and/or functional changes. This is the case of people who suffered limb amputation and show changes of body map organization within the somatosensory cortex (S1) of the deafferented cerebral hemisphere (contralateral to the amputated limb), as well as in the afferented hemisphere (ipsilateral to the amputated limb). Although several studies have approached these functional changes, the possible finer morphological alterations, such as those occurring in callosal axons, still remain unknown. The present work combined histochemistry, single-axon tracing and 3D microscopy to analyze the fine morphological changes that occur in callosal axons of the forepaw representation in early amputated rats. We showed that the forepaw representation in S1 was reduced in the deafferented hemisphere and expanded in the afferented side. Accordingly, after amputation, callosal axons originating from the deafferented cortex undergo an expansion of their terminal arbors with increased number of terminal boutons within the homotopic representation at the afferented cerebral hemisphere. Similar microscale structural changes may underpin the macroscale morphological and functional phenomena that characterize limb amputation in humans.
Assuntos
Amputação Traumática/fisiopatologia , Axônios/fisiologia , Corpo Caloso/fisiopatologia , Plasticidade Neuronal , Terminações Pré-Sinápticas/fisiologia , Córtex Somatossensorial/fisiopatologia , Amputação Traumática/patologia , Animais , Axônios/patologia , Corpo Caloso/patologia , Membro Anterior/cirurgia , Masculino , Técnicas de Rastreamento Neuroanatômico , Terminações Pré-Sinápticas/patologia , Ratos Wistar , Córtex Somatossensorial/patologiaRESUMO
Background: Patients with intractable seizures who are not candidates for focal resective surgery are indicated for a palliative surgical procedure, the callosotomy. This procedure is based on the hypothesis that the corpus callosum is an important pathway for interhemispheric spread of epileptic activity and, for drug resistant epilepsy. It presents relatively low permanent morbidity and an efficacy in the control of seizures. Based on literature, the corpus callosotomy improves the quality of life of patients that has the indication to perform this procedure because it allows reducing the frequency of seizures, whether tonic or atonic, tonic-clonic, absence or frontal lobe complex partial seizures. Aim: The aim of this literature review is discuss the technical details, modalities, risks, complications, results as well de prognosis of callosotomy based on critical literature review and the authors experience. Casuistry and Methods: It was performed bibliographical consultation, using the databases MEDLINE, LILACS, SciELO, utilizing language as selection criteria, choosing preferably recent articles in Portuguese, Spanish or English, with publication year higher than 2000. Conclusion: According to authors experience and references, callosotomy is a safe procedure when indicated to selected cases and the success rate is proportional to the extent of callosal resection. A greater resection can reduce the seizure frequency, however the morbidity may also be larger. There is no important study comparing VNS versus Callosotomy versus VNS plus callososotomy, what would be for future necessary for an important source of data about this topic.
Introducción: Los pacientes con convulsiones intratables que no son candidatos para la cirugía de resección focal están indicados para un procedimiento quirúrgico paliativo, la callosotomía. Este procedimiento se basa en la hipótesis de que el cuerpo calloso es una importante vía para la propagación interhemisférica de la actividad epiléptica y, para la epilepsia resistente a fármacos. Presenta relativamente baja morbilidad permanente y una eficacia en el control de las convulsiones. Sobre la base de la literatura, la callostomía mejora la calidad de vida de los pacientes que tiene la indicación para realizar este procedimiento, ya que permite reducir la frecuencia de las crisis, ya sean tónica o átona, tónico-clónicas, ausencia o lóbulo frontal crisis parciales complejas. Objetivo: El objetivo de esta revisión de la literatura es discutir los detalles técnicos, modalidades, riesgos, complicaciones, resultados y de pronóstico de callosotomía basado en la revisión crítica de la literatura y la experiencia de los autores. Casuística y Métodos: Se realizó la consulta bibliográfica, utilizando la base de datos MEDLINE, LILACS, SciELO, que utiliza el lenguaje como criterios de selección, la elección de los artículos recientes preferiblemente en portugués, español o Inglés, con el año de publicación superior a 2000. Conclusión: De acuerdo con la experiencia y las referencias del autor, callosotomía es un procedimiento seguro cuando indicado para casos seleccionados y la tasa de éxito es proporcional a la extensión de la resección del cuerpo calloso. A mayor resección puede reducir la frecuencia de las crisis, sin embargo, la morbilidad puede ser también mayor. No hay ningún estudio que compara la estimulación del nervio vago frente a frente callosotomía VNS más callososotomy, lo que sería la futura necesaria para una importante fuente de datos sobre este tema.
Assuntos
Humanos , Corpo Caloso/cirurgia , Corpo Caloso/fisiopatologia , Epilepsias Parciais , Resistência a Medicamentos , Prognóstico , Procedimentos Cirúrgicos Operatórios/métodosRESUMO
Mild cognitive impairment (aMCI) is a clinical condition, with high risk to develop Alzheimer's disease. Physical exercise may have positive effect on cognition and brain structure in older adults. However, it is still under research whether these influences are true on aMCI subjects with low Ab_42 and high total tau in cerebrospinal fluid (CSF), which is considered a biomarker for AD. Therefore, we aimed to investigate a possible relation between aerobic fitness (AF) and gray matter (GM) volume and AF and white matter (WM) integrity in aMCI with a CSF biomarker. Twenty-two participants with aMCI acquired the images on a 3.0-T MRI. AF was assessed by a graded exercise test on a treadmill. Voxel-based morphometry and tract-based spatial statistic methods were used to analyze the GM volume and WM microstructural integrity, respectively. We correlated AF and GM volume and WM integrity in aMCI (p < 0.05, FWE corrected, cluster with at least five voxels). There was a positive relation between AF and GM volume mostly in frontal superior cortex. In WM integrity, AF was positively correlated with fractional anisotropy and negatively correlated with mean diffusivity and radial diffusivity, all in the same tracts that interconnect frontal, temporal, parietal, and occipital areas (longitudinal fasciculus, fronto-occipital fasciculus, and corpus callosum). These results suggest that aerobic fitness may have a positive influence on protection of brain even in aMCI CSF biomarker, a high-risk population to convert to AD.
Assuntos
Envelhecimento/fisiologia , Encéfalo/diagnóstico por imagem , Disfunção Cognitiva/reabilitação , Corpo Caloso/diagnóstico por imagem , Terapia por Exercício/métodos , Aptidão Física/fisiologia , Idoso , Idoso de 80 Anos ou mais , Anisotropia , Encéfalo/fisiopatologia , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/fisiopatologia , Corpo Caloso/fisiopatologia , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Testes NeuropsicológicosRESUMO
OBJECTIVE: To investigate the acute role of the corpus callosum in inter- and intrahemispheric temporal coupling. METHODS: Intraoperative electrocorticography (ECoG) makes it possible to investigate the acute role of the corpus callosum in cortical temporal coupling, or synchrony, without additional surgical intervention, thus avoiding the confounding effects of scalp recordings and the long-term reorganization of functional connectivity. ECoGs were recorded in three patients during callosotomies. Bilateral electrode grids were placed over the frontal cortex. ECoGs were recorded immediately before and after performing the anterior two-thirds callosal transection, were digitalized at a sampling rate of 512Hz, inspected for artifacts, and later analyzed offline. Cross-correlation between inter- and intrahemispheric electrode pairs were obtained for 1Hz bins and special broad bands obtained by principal component analysis for each patient pre- and post-callosotomy. RESULTS: A statistically significant change was observed in intrahemispheric temporal coupling between electrode pairs that exceeded the confidence limit of correlation. CONCLUSIONS: Present results show that interrupting the influence of the corpus callosum has an acute effect on intrahemispheric activity by decreasing temporal coupling between cortical areas. SIGNIFICANCE: Intrahemispheric temporal coupling does not depend exclusively on ipsilateral cortico-cortical pathways or on subcortical influences, but also on callosal pathways.
Assuntos
Mapeamento Encefálico/métodos , Corpo Caloso/fisiopatologia , Corpo Caloso/cirurgia , Sincronização Cortical , Eletroencefalografia , Monitorização Neurofisiológica Intraoperatória , Lobo Temporal/fisiopatologia , Adulto , Eletrodos , Análise de Fourier , Humanos , Masculino , Processamento de Sinais Assistido por ComputadorRESUMO
Alzheimers disease (AD) represents the most prevalent neurodegenerative disorder that causes cognitive decline in old age. In its early stages, AD is associated with microstructural abnormalities in white matter (WM). In the current study, multiple indices of diffusion tensor imaging (DTI) and brain volumetric measurements were employed to comprehensively investigate the landscape of AD pathology. The sample comprised 58 individuals including cognitively normal subjects (controls), amnestic mild cognitive impairment (MCI) and AD patients. Relative to controls, both MCI and AD subjects showed widespread changes of anisotropic fraction (FA) in the corpus callosum, cingulate and uncinate fasciculus. Mean diffusivity and radial changes were also observed in AD patients in comparison with controls. After controlling for the gray matter atrophy the number of regions of significantly lower FA in AD patients relative to controls was decreased; nonetheless, unique areas of microstructural damage remained, e.g., the corpus callosum and uncinate fasciculus. Despite sample size limitations, the current results suggest that a combination of secondary and primary degeneration occurrs in MCI and AD, although the secondary degeneration appears to have a more critical role during the stages of disease involving dementia.
Assuntos
Doença de Alzheimer/patologia , Disfunção Cognitiva/patologia , Corpo Caloso/patologia , Hipocampo/patologia , Idoso , Idoso de 80 Anos ou mais , Anisotropia , Mapeamento Encefálico , Estudos de Casos e Controles , Corpo Caloso/fisiopatologia , Difusão , Imagem de Tensor de Difusão , Feminino , Giro do Cíngulo/patologia , Giro do Cíngulo/fisiopatologia , Hipocampo/fisiopatologia , Humanos , Masculino , Análise Multivariada , Tamanho do Órgão , Degeneração Walleriana/patologiaRESUMO
PURPOSE: To analyze the ventricular enlargement and myelination of the corpus callosum in adult dogs after four and eight weeks of kaolin-induction of hydrocephalus. METHODS: 36 dogs were randomly divided into 3 groups: 1 - without hydrocephalus, 2 - kaolin-induction of hydrocephalus until the fourth week, and 3 - kaolin-induction of hydrocephalus until the eighth week. Ventricular ratios and volumes were calculated using magnetic resonance images, and myelination of the corpus callosum were histologically evaluated using solocromo-cianin stain. RESULTS: Radiological hydrocephalus was observed in 93.75% and overall mortality was 38.4%. Ventricular volumes and ratios were higher in groups 2 and 3 compared to group 1 and similar when measures in the fourth and eighth weeks were compared in the group 3. Indices of luminescence in the knee and in the splenium of the corpus callosum were higher in group 2 than in group 1 indicating that there was loss of myelin in group 2, and similar in groups 1 and 3, showing a tendency to remyelination after 8 weeks. CONCLUSION: The corpus callosum of dogs with kaolin-induced hydrocephalus responds with demyelination of the knee and splenium by the fourth week with a tendency to remyelination by the eighth week.
Assuntos
Ventrículos Cerebrais/fisiopatologia , Corpo Caloso/fisiopatologia , Modelos Animais de Doenças , Ventrículos do Coração/fisiopatologia , Hidrocefalia/fisiopatologia , Caulim , Silicatos de Alumínio , Animais , Ventrículos Cerebrais/patologia , Corpo Caloso/patologia , Cães , Feminino , Hidrocefalia/induzido quimicamente , Imageamento por Ressonância Magnética , Masculino , Bainha de Mielina/fisiologia , Tamanho do Órgão , Distribuição Aleatória , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
Male bonnet monkeys (Macaca radiata) were subjected to the variable foraging demand (VFD) early stress paradigm as infants, MRI scans were completed an average of 4 years later, and behavioral assessments of anxiety and ex-vivo corpus callosum (CC) measurements were made when animals were fully matured. VFD rearing was associated with smaller CC size, CC measurements were found to correlate with fearful behavior in adulthood, and ex-vivo CC assessments showed high consistency with earlier MRI measures. Region of interest (ROI) hippocampus and whole brain voxel-based morphometry assessments were also completed and VFD rearing was associated with reduced hippocampus and inferior and middle temporal gyri volumes. The animals were also characterized according to serotonin transporter genotype (5-HTTLPR), and the effect of genotype on imaging parameters was explored. The current findings highlight the importance of future research to better understand the effects of stress on brain development in multiple regions, including the corpus callosum, hippocampus, and other regions involved in emotion processing. Nonhuman primates provide a powerful model to unravel the mechanisms by which early stress and genetic makeup interact to produce long-term changes in brain development, stress reactivity, and risk for psychiatric disorders.
Assuntos
Ansiedade/patologia , Ansiedade/fisiopatologia , Corpo Caloso , Hipocampo , Estresse Psicológico/patologia , Estresse Psicológico/fisiopatologia , Análise de Variância , Animais , Comportamento Animal , Mapeamento Encefálico , Corpo Caloso/crescimento & desenvolvimento , Corpo Caloso/patologia , Corpo Caloso/fisiopatologia , Estudos Transversais , Medo , Frequência do Gene , Genótipo , Hipocampo/crescimento & desenvolvimento , Hipocampo/patologia , Hipocampo/fisiopatologia , Processamento de Imagem Assistida por Computador , Modelos Lineares , Macaca radiata , Imageamento por Ressonância Magnética , Masculino , Proteínas da Membrana Plasmática de Transporte de Serotonina/genéticaRESUMO
PURPOSE: To analyze the ventricular enlargement and myelination of the corpus callosum in adult dogs after four and eight weeks of kaolin-induction of hydrocephalus. METHODS: 36 dogs were randomly divided into 3 groups: 1 - without hydrocephalus, 2 - kaolin-induction of hydrocephalus until the fourth week, and 3 - kaolin-induction of hydrocephalus until the eighth week. Ventricular ratios and volumes were calculated using magnetic resonance images, and myelination of the corpus callosum were histologically evaluated using solocromo-cianin stain. RESULTS: Radiological hydrocephalus was observed in 93.75 percent and overall mortality was 38.4 percent. Ventricular volumes and ratios were higher in groups 2 and 3 compared to group 1 and similar when measures in the fourth and eighth weeks were compared in the group 3. Indices of luminescence in the knee and in the splenium of the corpus callosum were higher in group 2 than in group 1 indicating that there was loss of myelin in group 2, and similar in groups 1 and 3, showing a tendency to remyelination after 8 weeks. CONCLUSION: The corpus callosum of dogs with kaolin-induced hydrocephalus responds with demyelination of the knee and splenium by the fourth week with a tendency to remyelination by the eighth week.
OBJETIVO: Analisar a dilatação ventricular e a mielinização do corpo caloso em cães adultos após quatro e oito semanas da indução de hidrocefalia por caulin. MÉTODOS: 36 cães foram aleatoriamente divididos em 3 grupos: 1- sem hidrocefalia, 2- quatro semanas de hidrocefalia induzida por caulin, 3- oito semanas de hidrocefalia induzida por caulin. As razões e volumes ventriculares foram calculados utilizando imagens de ressonância magnética, e, a mielinização do corpo caloso por estudo histológico (coloração com solocromo- cianina). RESULTADOS: Hidrocefalia foi observada radiologicamente em 93,75 por cento e a mortalidade global foi de 38,4 por cento. Os volumes e as razões ventriculares foram maiores nos grupos 2 e 3 em relação ao grupo 1 e semelhantes nas quarta e oitava semanas no grupo 3. Índices de luminescência no joelho e no esplênio do corpo caloso foram maiores no grupo 2 em relação ao grupo 1, indicando que houve perda de mielina no grupo 2, e semelhantes nos grupos 1 e 3, mostrando uma tendência à remielinização em torno de 8 semanas. CONCLUSÃO: O corpo caloso de cães com hidrocefalia induzida por caulin responde com desmielinização no joelho e esplênio em torno de quatro semanas com tendência à remielinização em torno da oitava semana.
Assuntos
Animais , Cães , Feminino , Masculino , Ventrículos Cerebrais/fisiopatologia , Corpo Caloso/fisiopatologia , Modelos Animais de Doenças , Ventrículos do Coração/fisiopatologia , Hidrocefalia/fisiopatologia , Caulim , Silicatos de Alumínio , Ventrículos Cerebrais/patologia , Corpo Caloso/patologia , Hidrocefalia/induzido quimicamente , Imageamento por Ressonância Magnética , Bainha de Mielina/fisiologia , Tamanho do Órgão , Distribuição Aleatória , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
The ventral medial prefrontal cortex (vMPFC) comprises the prelimbic cortex (PL) and the infralimbic cortex (IL). Conflicting results have been reported from studies aiming to investigate the role played by the vMPFC in behavioral and autonomic responses evoked in rodents exposed to experimental protocols that promote defense responses. Acute restraint is an unavoidable stress situation that evokes marked and sustained cardiovascular changes, which are characterized by elevated blood pressure (BP) and intense heart rate (HR) increases. We report here a comparison between the effects of pharmacological inhibition of IL and PL neurotransmission on BP and HR responses evoked by acute restraint in rats. Bilateral microinjection of 200 nl of the unspecific synaptic blocker CoCl(2) (1 mM) into the PL increased HR response associated with restraint, without affecting the restraint-induced BP response. However, when local synapses in the IL were inhibited by bilateral injection of CoCl(2) into that area, the restraint-induced HR increases were significantly reduced, without a significant effect on the concomitant BP response. No responses were observed when CoCl(2) was microinjected into structures surrounding the vMPFC, such as the cingulate cortex area 1, the corpus callosum, or the tenia tecta. The present results confirm the involvement of the vMPFC in modulation of the tachycardiac response evoked by acute restraint but not of the restraint-evoked blood pressure response. They also indicate that the IL and PL areas have opposite roles in the cardiac response, facilitating and reducing, respectively, restraint-evoked tachycardiac responses.
Assuntos
Córtex Pré-Frontal/fisiopatologia , Restrição Física , Estresse Psicológico/fisiopatologia , Taquicardia/fisiopatologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Fármacos do Sistema Nervoso Central/farmacologia , Cobalto/farmacologia , Corpo Caloso/efeitos dos fármacos , Corpo Caloso/fisiopatologia , Giro do Cíngulo/efeitos dos fármacos , Giro do Cíngulo/fisiopatologia , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Masculino , Microinjeções , Córtex Pré-Frontal/efeitos dos fármacos , Ratos , Ratos Wistar , Transmissão Sináptica/efeitos dos fármacosRESUMO
Inter-hemispheric modulation has been extensively studied, as it is critical for human behavior and could be involved in the development of neuropsychiatric disorders, such as major depression, epilepsy and stroke. Malnutrition early in life can alter brain processes such as inter-hemispheric modulation and these alterations can persist into adulthood. Here, we used cortical spreading depression (CSD) as a neurophysiological parameter to investigate inter-hemispheric modulation in 19 well-nourished and 18 early-malnourished male adult rats. CSD was evoked on the right frontal region and monitored at two parietal points on the same hemisphere. After a 2 h baseline recording, fibers projecting from the left to the right hemisphere via the corpus callosum were cut with a longitudinal lesion in the contralateral cortex and recording continued for two more hours. The results show that (1) baseline CSD propagation velocities were higher in the malnourished rats, as compared to the respective well-nourished controls; (2) post-lesion velocities increased in both nutritional groups, as compared with the baseline values; (3) this CSD increase persisted 3-7 days after lesion, suggesting a lasting effect and (4) in the malnourished group the post-lesion CSD enhancement was of smaller amplitude. Furthermore, a midline lesion (callosotomy) in eight well-nourished rats similarly facilitated CSD, suggesting the involvement of callosal fibers on this effect. No differences were found in sham-operated rats (21 well-nourished and 21 malnourished), as well as in a superficial (1 mm deep) contralateral lesion group (8 well-nourished). Results support the hypothesis of a lasting inhibitory contralateral influence on CSD propagation, which is attenuated, but not abolished, by early malnutrition.
Assuntos
Corpo Caloso/fisiologia , Desnutrição/fisiopatologia , Fibras Nervosas/fisiologia , Desnutrição Proteico-Calórica/fisiopatologia , Animais , Peso Corporal , Corpo Caloso/anatomia & histologia , Corpo Caloso/patologia , Corpo Caloso/fisiopatologia , Modelos Animais de Doenças , Feminino , Lateralidade Funcional , Masculino , Gravidez , Desnutrição Proteico-Calórica/patologia , Ratos , Ratos Wistar , Valores de Referência , DesmameRESUMO
We studied the relationships between magnetic resonance imaging (MRI) findings and neuropsychological sequelae in children after severe traumatic brain injury. Twenty-three children ages 7-13 years underwent MRI assessment of brain lesion topography and volume and neuropsychological evaluations, more than 1 year after sustaining severe traumatic brain injury. Most children had lesions to the corpus callosum and frontal lobes. Total lesion volume and extent of cerebral atrophy did not impact on the neuropsychological evaluation. Additional relationships were observed: left frontal lesions with lower semantic verbal fluency, right occipital lesions with lower visual recognition task scores, dyscalculia with cerebellar lesions, and cerebellar damage with lower cognitive performances and lower visual recognition memory. This study demonstrates the significance of the cerebellum's role in neuropsychological outcomes after traumatic brain injury and the importance of the lesion depth classification in predicting functional results.
Assuntos
Lesões Encefálicas/patologia , Lesões Encefálicas/psicologia , Doenças Cerebelares/patologia , Doenças Cerebelares/psicologia , Cerebelo/lesões , Cerebelo/patologia , Adolescente , Fatores Etários , Lesões Encefálicas/fisiopatologia , Doenças Cerebelares/etiologia , Cerebelo/fisiopatologia , Criança , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/patologia , Transtornos Cognitivos/fisiopatologia , Corpo Caloso/lesões , Corpo Caloso/patologia , Corpo Caloso/fisiopatologia , Avaliação da Deficiência , Feminino , Lobo Frontal/lesões , Lobo Frontal/patologia , Lobo Frontal/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Transtornos da Memória/etiologia , Transtornos da Memória/patologia , Transtornos da Memória/fisiopatologia , Testes Neuropsicológicos , Lobo Occipital/lesões , Lobo Occipital/patologia , Lobo Occipital/fisiopatologia , Reconhecimento Visual de Modelos/fisiologia , Prognóstico , Distúrbios da Fala/etiologia , Distúrbios da Fala/patologia , Distúrbios da Fala/fisiopatologia , Transtornos da Visão/etiologia , Transtornos da Visão/patologia , Transtornos da Visão/fisiopatologiaRESUMO
In this paper, novel methods were used to map the corpus callosum morphology of children with chromosome 22q11.2 deletion syndrome in order to further investigate changes to that structure and to examine their possible effects on cognitive function. The callosal profiles were extracted from the centermost MRI midsagittal slice by supervised thresholding and the structure's boundary and midline were computed automatically. Difference analysis was based on non-rigid registration, in which a template image is warped to conform to the shape of each corpus callosum in the sample. Boundaries and midlines were registered to a template and the results used to determine the average callosal shapes for children with the deletion and for controls. Pointwise registration also enabled the detailed evaluation of callosal curvature, width, area and length. Significant differences between the two groups were found in shape, size and bending angle. Results showed group differences that were concentrated in the anterior part of the structure, more specifically in the rostrum, which was larger and longer in the group with the syndrome. Correlation analyses showed that ventricular enlargement does not fully account for callosal morphology differences in children with the deletion. However, areal measurements did reveal important relationships between changes in callosal morphology and cognitive function. These novel findings reveal intricate relationships between genetic and disease-specific factors in the callosal anatomy and the potential impact of those changes on cognitive functions.
Assuntos
Agenesia do Corpo Caloso , Transtornos Cromossômicos/patologia , Transtornos Cognitivos/patologia , Síndrome de DiGeorge/patologia , Malformações do Sistema Nervoso/patologia , Adolescente , Córtex Cerebral/anormalidades , Córtex Cerebral/fisiopatologia , Criança , Transtornos Cromossômicos/genética , Transtornos Cromossômicos/fisiopatologia , Transtornos Cognitivos/genética , Transtornos Cognitivos/fisiopatologia , Corpo Caloso/fisiopatologia , Síndrome de DiGeorge/genética , Síndrome de DiGeorge/fisiopatologia , Feminino , Genótipo , Humanos , Deficiência Intelectual/genética , Deficiência Intelectual/patologia , Deficiência Intelectual/fisiopatologia , Imageamento por Ressonância Magnética , Masculino , Mutação/genética , Malformações do Sistema Nervoso/genética , Malformações do Sistema Nervoso/fisiopatologia , Vias Neurais/anormalidades , Vias Neurais/fisiopatologiaRESUMO
We tested the hypothesis that the ontogenetic development of the corpus callosum (CC) affects the consistency of laterality in a paw preference task. Adult male mice (55 normal and 29 acallosal) of the BALB/cCF strain were initially tested (twice; inter-test interval: 72 h) in an unbiased setup in which both forepaws could easily perform a reaching movement. In a subsequent test, animals were placed in a biased setup that favored the use of the non-preferred paw. Acallosal and normal mice were strongly lateralized in the unbiased setup. Additionally, while normal mice did not present a populational bias favoring one of the paws, acallosal mice presented a significant bias favoring the left paw. In the biased setup, left- and right-pawed normal mice were equally consistent (approximately 65% of the animals, in both groups, used the preferred paw of the initial two tests, in spite of the bias). Conversely, while left-pawed acallosal mice were as consistent (65%) as normal mice, only 20% of right-pawed mice were consistent. These results suggest that the development of the CC affects consistency of laterality in a side-dependent manner. These results are discussed considering the role of the CC in the establishment of behavioral lateralization.
Assuntos
Agenesia do Corpo Caloso , Comportamento Animal/fisiologia , Corpo Caloso/fisiopatologia , Lateralidade Funcional/fisiologia , Animais , Comportamento de Escolha/fisiologia , Pé/fisiologia , Membro Anterior/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Mutantes Neurológicos , Valores de Referência , Reprodutibilidade dos Testes , Especificidade da Espécie , Estatísticas não ParamétricasRESUMO
El presente estudio esta dirigido a analizar las indicaciones y anatomia quirurgica del abordaje transcalloso - interfornicial al IIIer ventriculo. El adecuado conocimiento de la relacion anatomica existente entre el cuerpo callos , el septum lucidum y el fornix permite llevar a cabo estos procedimientos sin comprometer significativamente a esas estructuras, evitando secuelas neuropsicologicas irreversibles (AU)
Assuntos
Corpo Caloso/anatomia & histologia , Corpo Caloso/cirurgia , Corpo Caloso/fisiopatologia , Terceiro Ventrículo/anatomia & histologiaRESUMO
A sotura realiza uma revisäo da literatura, estudando o dimorfismo sexual no corpo caloso humano
Assuntos
Humanos , Caracteres Sexuais , Corpo Caloso/anatomia & histologia , Corpo Caloso/fisiopatologia , Caracteres Sexuais , CérebroRESUMO
In this study we analyzed the effect of neonatal monocular enucleation on the pattern of callosal connections in striate cortex of the golden hamster. Callosal connections were revealed in the hemisphere ipsilateral to the remaining eye following multiple injections of either the enzyme horseradish peroxidase or the fluorescent tracer Fluoro-Gold into the contralateral hemisphere. The most salient anomaly induced by the removal of one eye at birth is the appearance of a dense band of callosal connections that runs anteroposteriorly in medial portions of striate cortex. No obvious changes in the laminar distribution of callosal connections were observed. Comparison of our present results with those obtained by Olavarria et al (1987) in monocularly enucleated rats reveals that neonatal enucleation induces remarkably similar anomalies in the callosal patterns of rats and hamsters. This similarity suggests that the role the eyes play in the development of the visual callosal pathway is similar among rodent species. Moreover, the finding of an anomalous callosal band in striate cortex one-eyed hamsters supports the notion that disruption of visual input does not arrest callosal development, but rather leads to the development of entirely new features in the callosal pattern.
Assuntos
Corpo Caloso/fisiopatologia , Enucleação Ocular , Córtex Visual/fisiopatologia , Animais , Cricetinae , Humanos , Recém-Nascido , Transtornos da Visão/fisiopatologiaRESUMO
In this study we analyzed the effect of neonatal monocular enucleation on the pattern of callosal connections in striate cortex of the golden hamster. Callosal connections were revealed in the hemisphere ipsilateral to the remaining eye following multiple injections of either the enzyme horseradish peroxidase or the fluorescent tracer Fluoro-Gold into the contralateral hemisphere. The most salient anomaly induced by the removal of one eye at birth is the appearance of a dense band of callosal connections that runs anteroposteriorly in medial portions of striate cortex. No obvious changes in the laminar distribution of callosal connections were observed. Comparison of our present results with those obtained by Olavarria et al (1987) in monocularly enucleated rats reveals that neonatal enucleation induces remarkably similar anomalies in the callosal patterns of rats and hamsters. This similarity suggests that the role the eyes play in the development of the visual callosal pathway is similar among rodent species. Moreover, the finding of an anomalous callosal band in striate cortex one-eyed hamsters supports the notion that disruption of visual input does not arrest callosal development, but rather leads to the development of entirely new features in the callosal pattern
Assuntos
Animais , Cricetinae , Humanos , Recém-Nascido , Corpo Caloso/fisiopatologia , Enucleação Ocular , Córtex Visual/fisiopatologia , Transtornos da Visão/fisiopatologiaRESUMO
Although many patients with dominant hemisphere damage retain some reading ability, the anatomic substrate of the preserved reading remains controversial. We tested the hypothesis that the right hemisphere mediates the reading of some patients with acquired dyslexia by using Transcranial Magnetic Stimulation (TMS) to assess the effect of transient cortical stimulation on reading. A patient with (partially recovered) pure alexia was asked to read aloud briefly presented words, half of which were shown in association with TMS of the right or left hemisphere. Consistent with the right hemisphere reading hypothesis, stimulation of the right but not the left hemisphere disrupted oral reading.
Assuntos
Corpo Caloso/fisiologia , Lateralidade Funcional/fisiologia , Corpos Geniculados/fisiologia , Leitura , Estimulação Magnética Transcraniana , Infarto Cerebral/patologia , Infarto Cerebral/fisiopatologia , Corpo Caloso/patologia , Corpo Caloso/fisiopatologia , Dislexia Adquirida/patologia , Dislexia Adquirida/fisiopatologia , Corpos Geniculados/patologia , Corpos Geniculados/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-IdadeRESUMO
The interhemispheric disconnection syndrome secondary to a callosal haemorrhage is exceedingly uncommon. In the present study, 3 patients with haemorrhages restricted to the corpus callosum are presented. All 3 developed a partial anterior interhemispheric disconnection syndrome: unilateral tactile anomia, unilateral agraphia, unilateral apraxia, difficulty in copying drawings, dyscalculia as well as abnormalities of somaesthetic transfer and the 'alien hand' sign. The study of these cases allowed a close examination of the association between deficits in the transfer of specific neuropsychological information and the precise topography of callosal damage. Variability in the lateralization of cognitive functions, and possible mechanisms underlying the production of callosal haemorrhages after the rupture of saccular aneurysms are also discussed.