Anatomía del cuerpo calloso en ratas sometidas a estrés prenatal crónico / Anatomy of corpus callosum in rats submitted to chronic prenatal stress

RESUMEN: El cuerpo calloso (CC), es la mayor comisura de sustancia blanca del encéfalo de los mamíferos placentados, constituida por numerosos haces de fibras transversales que conectan áreas corticales de ambos hemisferios cerebrales. Por otro lado, el estrés se define como una respuesta general del organismo ante demandas externas o internas, inicialmente amenazantes, que consiste en movilizar recursos fisiológicos y psicológicos para poderlas afrontar. Dada la importancia del cuerpo calloso en las conexiones cortico-corticales, el objetivo del presente estudio, fue evaluar el efecto en ratas, de un estrés prenatal crónico por inmovilización, sobre la anatomía macroscópica del CC. Se utilizaron seis ratas preñadas de la cepa Wistar de 250 g, de las cuales tres fueron sometidas, a partir del octavo día postconcepción, a una restricción de movimiento por diez días (2h/día). Posteriormente, las madres prosiguieron su gestación, parto y lactancia. Al nacimiento, las camadas fueron ajustadas a seis crías machos por madre (n=36), destetadas a los 21 días y sacrificadas a los 45-52 días de edad. Los encéfalos fueron seccionados a través de la cisura interhemisférica y ambos hemisferios fotografiados por su cara medial. Las imágenes fueron digitalizadas y analizadas mediante el programa Scion Image®, para la medición del área total, parciales (tercio anterior, medio, posterior y quinto posterior) y perímetro callosal. Es así como, el estrés prenatal por inmovilización, afectó significativamente (p<0,01), la morfología macroscópica del cuerpo calloso. Evidenciándose una disminución del área total, áreas parciales y perímetro callosal, en los animales sometidos a restricción prenatal. Estableciendo una relación directa entre número de axones y área callosal e inversa entre diámetro y densidad axonal; lo observado podría tener incidencia en la transferencia interhemisférica.

SUMMARY: The Corpus Callosum (CC) is the largest white matter commissure in the brain of placental mammals, consisting of numerous transverse fiber bundles that connect cortical areas of both cerebral hemispheres. On the other hand, stress is defined as a general response of the organism to external or internal demands, initially threatening, which consists of mobilizing physiological and psychological resources to be able to face them. Given the importance of CC in cortico-cortical connections, the aim of the present study, was to evaluate the effect of chronic pre-natal immobilization stress on the macroscopic anatomy of CC in rats. Six 250g pregnant rats of the Wistar strain were used, of which three were subjected, starting on the eighth post-conception day, to movement restriction for ten days (2h/day). Subsequently, the mothers continued their gestation, delivery and lactation. At birth, litters were adjusted to six male offspring per mother (n=36), which were weaned at 21 days and slaughtered at 45-52 days of age. The brains were fixed, and later sectioned through the interhemispheric fissure and both hemispheres photographed by their medial aspect. The images were digitized and analyzed using the Scion Image® program, for the measurement of the total area, partial area (ante- rior, middle and posterior thirds, as well as posterior fifth) and callosal perimeter. Thus, prenatal stress due to immobilization significantly affected (p<0.01), the macroscopic morphology of the CC. Evidence shows a decrease in the total area, partial areas and callosal perimeter in the animals subjected to prenatal restraint, as compared to normal animals. Establishing a direct relationship between number of axons and callosal area and an inverse relationship between diameter and axonal density, what was observed may have an impact on interhemispheric transfer.

Corpus callosum size, is there a sexual difference? / Tamaño del cuerpo calloso, ¿existe una diferencia sexual?

Physical anthropometry is a subdivision of human anatomy science, which has uses in medical industries. A lot of studies showed that genetic, racial, and socioeconomic factors and educational background play rule in anthropometry. We aim this study to determine the presence of differences between gender and corpus callosum size. MRIs were collected from Ardebil and Kermanshah states done in 2013, the participants were informed about this study. They were selected based on age more than 20-years old, absence of demyelization and degenerative diseases, clean history of for neurosurgery, and previous cerebrovascular accidents. MRIs were analyzed by PmsDview program in the midsagittal section by using 9 landmarks, and the data was analyzed by SPSS 19.0. The mean corpus callosum in men was 551.9547±130.55 mm2, and 613.2353±99.98 mm2, and by using t-test (p<0.05), there was no difference in corpus callosum size in both genders. By comparing the results of this study results and other studies we believe that genetic, racial factors, beside education background play great rule to determine corpus callosum size. We suggest that such research to be done in other states of Iran, and Middle East and Asian countries which can confirm genetic and racial factors in anthropometry.

La antropometría física es una rama de la anatomía humana utilizada en las industrias médicas. Una gran cantidad de estudios ha demostrado que factores genéticos, raciales y socioeconómicos, así como antecedentes educativos forman parte de las reglas en la antropometría. Nuestro objetivo fue determinar la presencia de diferencias entre el sexo y el tamaño del cuerpo calloso. Se obtuvieron imágenes de resonancia magnética (IRM) pertenecientes a sujetos de los estados de Ardebil y Kermanshah en Irán, el año 2013. Los participantes fueron informados acerca del estudio y seleccionados en base a la edad y debían ser mayores de 20 años. Fueron incluidos casos con ausencia de desmielinización o enfermedades degenerativas, un historial sin antecedentes de neurocirugía o accidentes cerebrovasculares previos. Las IRM fueron analizadas con el programa PmsDview en la sección sagital mediana usando 9 puntos de referencia; los datos se analizaron con el programa SPSS 19.0. El tamaño promedio del cuerpo calloso en los hombres fue 551,9547±130,55 mm2, y en mujeres 613,2353±99,98 mm2. Mediante el uso de la prueba t (p<0,05), no hubo diferencia en el tamaño del cuerpo calloso en ambos sexos. Al comparar estos resultados con otros estudios, existen factores genéticos, raciales, además de la educación, que juegan un papel importante al determinar el tamaño del cuerpo calloso. Sugerimos que este tipo de investigación que se realice en otros estados de Irán, el Medio Oriente y en los países asiáticos, para confirmar que los factores genéticos y raciales modifican la antropometría.

Características Biométricas del Cuerpo Calloso en Individuos chilenos / Biometric Characteristics of the Corpus Callosum in Chilean Subjects

El cuerpo calloso conecta ambos hemisferios cerebrales y se ubica en el fondo de la fisura longitudinal del cerebro. Con el propósito de complementar el conocimiento sobre esta importante estructura del sistema nervioso en nuestra población, determinamos diversos parámetros biométricos, que incluyeron su localización respecto a los márgenes anterior y posterior de los hemisferios cerebrales, longitud, espesor a diversos niveles, entre otras variables. Se utilizaron 20 cerebros frescos, de individuos adultos, a los cuales se fotografió la cara medial de sus hemisferios, los que fueron acompañados con una regla antes de obtener la fotografía, con el objetivo de trabajar sobre la imagen y, de este modo, registrar las variables planificadas. Estas medidas fueron registradas con un caliper digital de 0,05 mm de precisión. La distancia promedio obtenida entre la parte más prominente de la rodilla del cuerpo calloso y el margen anterior del hemisferio cerebral fue de 35,4 mm y, entre la parte más prominente del esplenio y el margen posterior del hemisferio cerebral fue de 52,8 mm. La longitud antero-posterior del cuerpo calloso fue, en promedio, 88,2 mm. La distancia antero-posterior promedio de la parte media de la rodilla fue 13,2 mm y la de la parte media del esplenio 15,7 mm. Los datos obtenidos son un aporte al conocimiento biométrico y morfológico de esta importante estructura comisural, en nuestro grupo poblacional.

The corpus callosum is a structure of white matter connecting the two cerebral hemispheres and is located at the bottom of the longitudinal fissure of the brain. In order to complement the understanding of this important structure of the nervous system in our population, we determined various biometric parameters, which included its location in relation to the anterior and posterior margins of the cerebral hemispheres, length, thickness at various levels, among other variables. To do this, we used 20 fresh brains of adult individuals which the medial aspect of the hemispheres was photographed, and were accompanied with a ruler before you get the picture, with the aim of working on the image and thus record the planned variables. The average distance obtained between the most prominent part of the knee of the corpus callosum and the anterior margin of the cerebral hemisphere was 35.4 mm and among the most prominent part of the splenium and the posterior margin of cerebral hemisphere was 52.8 mm. Antero-posterior length of the corpus callosum was on average 88.2 mm, the average antero-posterior diameter from the middle of the knee was 13.2 mm and that of the middle part of splenius 15.7 mm. The data obtained contribute to the biometric and morphological knowledge of this important commissural structure in our population group.

Anatomy of corpus callosum in prenatally malnourished rats

The effect of prenatal malnutrition on the anatomy of the corpus callosum was assessed in adult rats (45-52 days old). In the prenatally malnourished animals we observed a significant reduction of the corpus callosum total area, partial areas, and perimeter, as compared with normal animals. In addition, the splenium of corpus callosum (posterior fifth) showed a significant decrease of fiber diameters in the myelinated fibers without changing density. There was also a significant decrease in diameter and a significant increase in density of unmyelinated fibers. Measurements of perimeter's fractal dimensions from sagittal sections of the brain and corpus callosum did not show significant differences between malnourished and control animals. These findings indicate that cortico-cortical connections are vulnerable to the prenatal malnutrition, and suggest this may affect interhemispheric conduction velocity, particulary in visual connections (splenium).

Transseptumpellucidumrostrostomy: anatomical considerations and neuroendoscopic approach / Transseptopelucidorostrostomia: considerações anatômicas e abordagem neuroendoscópica

PURPOSE: Verify the presence of the rostral lamina of the corpus callosum, and set parameters for neuroendoscopy. METHODS: Relationship of the floor of the frontal horn of lateral ventricle and the hypothalamic-septal region were studied after sagittal and axial sections of the brains. Measurements were compared using F and Student t tests. The correlations between anterior-posterior diameter of the interventricular foramen / anterior-posterior diameter of the fornix column, and between anterior-posterior diameter of the interventricular foramen / length of the rostral lamina were performed by Pearson index test. RESULTS: There was no statistically significant difference in measurements performed in both hemispheres (p<0.05). Positive correlations were observed between the anterior-posterior diameter of the interventricular foramen / anterior-posterior diameter of the fornix column (R = 0.35), and between the anterior-posterior diameter of the interventricular foramen / length of the rostral lamina (R = 0.23). CONCLUSION: Rostral lamina was observed in all brains. It was possible to perform an endoscopic fenestration in the rostral lamina, communicating safely the lateral ventricle with a polygonal subcallosal cistern.

OBJETIVO: Verificar a presença da lâmina rostral do corpo caloso e padronizar parâmetros para a realização de neuroendoscopia. MÉTODOS: A relação do assoalho do corno frontal do ventrículo lateral e a região hipotálamo-septal lateral foi estudada através de secções sagitais e axiais dos cérebros. As medidas foram comparadas utilizando os testes F e t-Student. As correlações entre diâmetro ântero-posterior do forame interventricular / diâmetro ântero-posterior da coluna do fornix, e entre o diâmetro ântero-posterior do forame interventricular / comprimento da lâmina rostral foram estudadas pelo teste de Pearson. RESULTADOS: Não houve diferença estatisticamente significante nas medidas realizadas em ambos hemisférios (p <0.05). Correlações positivas foram observadas entre diâmetros ântero-posteriores do forame interventricular / coluna do fornix (R = 0.35), os diâmetros ântero-posteriores do forame interventricular / comprimento da lâmina rostral (R = 0.23). CONCLUSÃO: A lâmina rostral foi observada em todos espécimes. Foi possível realizar uma fenestração endoscópica na lâmina rostral, comunicando com segurança o ventrículo lateral a uma cisterna poligonal subcalosa.

Effects of visual loss in the corpus callosum in rats subjected to sensory-motor training / Efectos de la deprivación visual en el cuerpo calloso en ratas sometidas a entrenamiento sensoriomotriz

The purpose of this study was to analyze the changes in the dimensions of different portions of the corpus callosum in rats subjected to sensory-motor enriched environment with visual loss. We used 24 adult Sprague¡Dawley rats divided into three groups: G1 (n = 7) control, G2 (n = 10) subjected to sensory-motor stimulation, and G3 (n = 7) subjected to sensory-motor stimulation followed by visual loss by retinal injury. The brains were extracted and the corpus callosum was divided into three parts of equal length, corresponding to the genu, mid-body, and splenium, and the callosal area was determined according to the method described by Aboitiz et al. (1992). We observed normal performance among animals in G2 and G3 in the enriched environment with a decrease in the area of the posterior third of the corpus callosum or splenium in G3. However, these differences were not statistically significant when compared with G1 and G2, which suggests that prior training to G3 retinal lesion favored the performance observed after the injury.

El propósito de este estudio fue analizar los cambios en las dimensiones de las diferentes porciones del cuerpo calloso en ratas sometidas a un medio ambiente enriquecido sensoriomotriz con deprivación visual. Se utilizaron 24 ratas Sprague Dawley adultas divididas en tres grupos: G1(n=7) control; G2 (n=10) sometidas a estimulación sensoriomotriz y G3 (n=7) sometidas a estimulación sensoriomotriz seguida de deprivación visual por lesión retiniana. Se obtuvieron los encéfalos y el cuerpo calloso fue dividido en tres tercios correspondiendo a la rodilla, tercio medio y esplenio. El área callosal se determinó de acuerdo al método descrito por Aboitiz et al. (1992). Encontramos un rendimiento normal de los animales de G2 y G3 en el medio ambiente enriquecido, con disminución en el área del tercio posterior o esplenio del cuerpo calloso en G3, aunque estas diferencias no fueron estadísticamente significativas al compararlas con el G1 y G2, lo que sugiere que el entrenamiento previo a la lesión retiniana de G3 favoreció el desempeño obtenido posterior a la lesión.

Measuring Fractional Anisotropy of the Corpus Callosum Using Diffusion Tensor Imaging: Mid-Sagittal versus Axial Imaging Planes

OBJECTIVE: Many diffusion tensor imaging (DTI) studies of the corpus callosum (CC) have been performed with a relatively thick slice thickness in the axial plane, which may result in underestimating the fractional anisotropy (FA) of the CC due to a partial volume effect. We hypothesized that the FA of the CC can be more accurately measured by using mid-sagittal DTI. We compared the FA values of the CC between the axial and mid-sagittal DTI. MATERIALS AND METHODS: Fourteen healthy volunteers underwent MRI at 3.0 T. DTI was performed in both the mid-sagittal and axial planes. One 5-mm mid-sagittal image and twenty-five 2-mm axial images were obtained for the CC. The five regions of interest (ROIs) that included the prefrontal (I), premotor and supplementary motor (II), motor (III), sensory (IV) and parietal, temporal and occipital regions (V) were drawn along the border of the CC on each sagittal FA map. The FA values obtained from each region were compared between the two sagittal maps. RESULTS: The FA values of all the regions, except for region V, were significantly increased on the mid-sagittal imaging. The FA values in region IV were significantly underestimated on the mid-sagittal image from the axial imaging, compared with those in the regions I and V (p = 0.037 and p = 0.001, respectively). CONCLUSION: The FA values of the CC were significantly higher on the mid-sagittal DTI than those on the axial DTI in regions I-IV, and particularly in the region IV. Mid-sagittal DTI may provide more accurate FA values of the CC than can the axial DTI, and mid-sagittal DTI may be more desirable for studies that compare between patients and healthy subjects.

Long distance communication in the human brain: timing constraints for inter-hemispheric synchrony and the origin of brain lateralization

Analysis of corpus callosum fiber composition reveals that inter-hemispheric transmission time may put constraints on the development of inter-hemispheric synchronic ensembles, especially in species with large brains like humans. In order to overcome this limitation, a subset of large-diameter callosal fibers are specialized for fast inter-hemispheric transmission, particularly in large-brained species. Nevertheless, the constraints on fast inter-hemispheric communication in large-brained species can somehow contribute to the development of ipsilateral, intrahemispheric networks, which might promote the development of brain lateralization.

Cuerpo calloso en el plano mediano de imágenes de resonancia magnética: perímetro, superficie y forma en relación a edad y sexo / Corpus callosum in the midsagital planum of magnetic resonance image: perimeter, surface and shape in relation with age and sex

Numerosas publicaciones sobre aspectos morfológicos del cuerpo calloso (cc) evidencian el interés, a la vez que la necesidad de aclarar discrepancias sobre la influencia de la edad y sexo. Abundante bibliografía se refiere a su superficie en el plano mediano del cerebro, pero pocas citas hacen referencia a su perímetro. El objetivo de este trabajo fue determinar perímetro y superficie del cuerpo calloso como también, establecer relaciones entredichos valores y el sexo, tamaño cerebral y edad (rango15-82 años y sub-rangos). En imágenes de resonancia magnética digitalizadas, de 194 sujetos normales de ambos sexos, se midieron, mediante el programa Scion Image for Windows, perímetro y superficie del cc en el plano mediano del cerebro y superficies cerebrales para sagitales. Los valores obtenidos se procesaron estadísticamente (ANOVA) y se correlacionaron (r de Pearson) con la edad. En ambos sexos, entre 15 y 40 años, la superficie aumenta significativamente (r: 0.33 y 0.60) y, después de los 60 años, disminuye (r:-0.72 y-0.78) pero no se modifica significativamente entre 41 y 60 años. Entre 15 y 82 años el perímetro aumenta leve y significativamente (r: 0.22 y 0.35). La superficie es mayor en la mujer solamente en relación al tamaño del cerebro. El trabajo aporta valores de perímetro y superficie del cc, los que varían significativamente con la edad pero no con el sexo. La relación entre ambos indica variaciones de la forma del cc con la edad. Se evidencia que si sólo se analizan amplios rangos de edades pueden obtenerse falsas conclusiones.

O corpo caloso: dimorfismo sexual / The corpus callosum: sexual dimorphism

A sotura realiza uma revisäo da literatura, estudando o dimorfismo sexual no corpo caloso humano

Sexual dimorphism in interhemispheric relations: anatomical-behavioral convergencea

An embryogenetic hypothesis states that hemispheric specialization is inversely related to callosal connectivity (Geschwind and Galaburda, 1985). We tested this hypothesis (i) anatomically by relating postmortem planum temporale asymmetry to regional callosal morphology and (ii) behaviorally by relating the right visual field advantage in a lateralized lexical decision task with associative primes to regional callosal morphometry using magnetic resonance imaging (MRI). The postmortem study showed a significant negative correlation between planum temporale asymmetry and the number of small diameter fibers in the isthmus of the corpus callosum, but only for males. The MRI study showed a significant negative correlation between the right visual hemifield advantage for associated words and the cross section size of the isthmus of the corpus callosum, but again only in males. There was no sex difference in either the anatomical asymmetry, the behavioral asymmetry, or the callosal morphology. These convergent results suggest that there is a sexual dimorphism in interhemispheric relations in humans

The anatomical substrates for language and hemispheric specialization

Three main lines of investigation are discussed in this paper: (1) the comparison between the anatomical arrangement of the language areas and the large-scale neurocognitive cortical networks partly involved in active or working memory; (2) the relations between hemispheric specialization and the development of interhemispheric communication; and (3) the analysis of individual differences in brain organization for language. The hypothesis and evidence presented stem from work being performed in our laboratories

Brain connections: interhemispheric fiber systems and anatomical brain asymmetries in humans

The present review summarizes some results of a research program oriented to determine the anatomical substrates of interhemispheric communication in humans, as seen in postmortem material. One main finding is a sensible pattern of histological differentiation along the corpus callosum, indicating specific properties of interhemispheric conduction for axonal fibers involved in different brain functions. Callosal regions that connect primary and secondary sensory and motor areas are characterized by a large proportion of fast-conducting, large-diameter fibers, while regions connecting the so-called association areas and prefrontal areas bear a high density of slow-conducting, lightly myelinated and thin fibers. These findings are interpreted in a functional context, suggesting that the fast-conducting fibers connecting sensory and motor areas contribute to fuse the two hemirepresentations in each hemisphere. It has also been determined that an increased callosal area indicates an increased number of callosal fibers, a finding that validates previous morphometric studies done in several laboratories. No sex differences in callosal size, shape, or in callosal fiber composition were found. Finally, an inverse relation was found between the anatomical asymmetries in the size of the Sylvian fissure and the size and number of fibers in specific segments of the corpus callosum. There were sex differences in terms of the particular callosal regions showing a significant correlation with asymmetries, and in terms of the fiber types that were correlated with asymmetries