ABSTRACT
The hippocampus plays a fundamental role in spatial learning and memory. Dentate gyrus (DG) granular neurons project mainly to proximal apical dendrites of neurons in the CA3 stratum lucidum and also, to some extent, to the basal dendrites of CA3 pyramidal cells in the stratum oriens. The terminal specializations of DG neurons are the mossy fibers (MF), and these huge axon terminals show expansion in the CA3 stratum oriens after the animals undergo overtraining in the Morris Water Maze task (MWM). However, to our knowledge there are no reports regarding the possible changes in density of post-synaptic targets of these terminals in the basal dendrites of CA3 neurons after overtraining in the MWM. The purpose of this work was to study the density of thorny excrescences (TE) and other dendritic spine types (stubby, thin, and mushroom) in the CA3 stratum oriens in animals overtrained in the MWM for three consecutive days and in animals trained for only one day. Seven days after MWM training, the animals were sacrificed, and their brains removed and processed for rapid Golgi staining to visualize the different types of dendritic protrusions. Our results revealed that the relative quantity of stubby, thin, and mushroom dendritic spines did not change, regardless of amount of training. However, a significant increase in the density of TE was detected in the overtrained animals. These results strongly suggest that spatial water maze overtraining induces an increased density of MF-TE connections, which might be functionally relevant for long-term spatial memory formation.
Subject(s)
CA3 Region, Hippocampal/cytology , Dendritic Spines , Morris Water Maze Test/physiology , Practice, Psychological , Pyramidal Cells , Animals , CA3 Region, Hippocampal/physiology , Dendritic Spines/physiology , Male , Memory, Long-Term/physiology , Pyramidal Cells/physiology , Rats , Rats, Sprague-Dawley , Spatial Memory/physiologyABSTRACT
Los niños sobrevivientes a cáncer cuya enfermedad y tratamiento involucra al Sistema Nervioso Central, presentan un patrón consistente de deficiencias neurocognoscitivas. En este artículo se describe el estudio de caso de un niño de 9 años diagnosticado con tumor de la fosa posterior sometido a cirugía, quimioterapia y radioterapia. Se aplicó la Batería Neuropsicológica Infantil en 3 momentos: posterior a la cirugía; finalizada la quimioterapia y la radioterapia y después del programa de rehabilitación cognoscitiva. Las evaluaciones neuropsicológicas después de la cirugía, quimio y radioterapia muestran deficiencias en las tareas de Habilidades Gráficas, Atención Visual y Auditiva, Porcentaje de Respuestas Correctas, Diseños Correctos con el Mínimo de Movimientos, Velocidad en la Lectura y la Escritura, Habilidades Gráficas, Codificación Visual, Memoria Verbal y Visual, Percepción Táctil, Repetición y Comprensión del Lenguaje, Habilidades Conceptuales, Fluidez Verbal y Gráfica, Precisión de la Lectura, Composición Narrativa, Conteo, Manejo Numérico y Cálculo. Después de la rehabilitación cognoscitiva observamos un incremento en el puntaje en las tareas de: Habilidades Gráficas, Memoria Verbal, Expresión y Comprensión del lenguaje, Atención Visual y Auditiva, Habilidades Conceptuales, Fluidez Verbal y Gráfica, Conteo, Manejo Numérico, Cálculo y Razonamiento Lógico Matemático. Con la implementación de las medidas normativas de la Evaluación Neuropsicológica Infantil pudimos contrastar el desempeño de nuestro paciente; el cual refleja que el programa de rehabilitación cognoscitiva potencialmente posee la eficacia suficiente para contrarrestar algunas de las secuelas neurocognoscitivas observadas después de la resección del tumor y de la radioterapia y la quimioterapia
Cancer surviving children, whose disease and treatment involves the central nervous system, show a consistent pattern of neurocognitive deficits. We report a case diagnose of a 9 years boy with posterior fossa tumor treated with surgery, chemotherapy and radiotherapy. Neuropsychological evaluation post oncological therapies and post Cognitive Remediation Program (CRP) were made to document the effect of neuropsychological rehabilitation. The results of the post oncological therapies evaluation shows deficits in Constructional Skills, Visual and Auditory Attention, Percentage of Correct Answers and Correct Designs with Minimal Movements, Speed in Reading and Writing, Graphic Skills, Visual Coding, Verbal and Visual Memory, Perception Touch, Repetition and Comprehension of Language, Conceptual Skills, Verbal and Graphics Fluency, Reading Accuracy, Narrative Composition, Count, Numerical and Calculation Management. After CRP our results illustrate an increase in the score of: Graphic Skills, Verbal Memory, Speech and Language Understanding, Conceptual Skills, Verbal and Graphics Fluency, Count, Numerical Management, Calculation and Logical Mathematical Reasoning after CRP. With the implementation of standardized measures of Evaluación Neuropsicológica Infantil we could compare the performance of our patient; which suggests that the CRP has enough potential to counteract some of the neurocognitive sequelae observed after tumor resection and radio and chemotherapy
Subject(s)
Child , Humans , Male , Neoplasms/psychology , Cognitive Behavioral Therapy/methods , Child Behavior Disorders/rehabilitation , Neuropsychological Tests/statistics & numerical data , Attention Deficit and Disruptive Behavior Disorders/epidemiologyABSTRACT
There is a wealth of information indicating that the hippocampal formation is important for learning and memory consolidation. The hippocampus is very sensitive to ageing and developmentally stressful factors such as prenatal malnutrition, which produces anatomical alterations of hippocampal pyramidal cells as well as impaired spatial learning. On the other hand, there are no reports about differential effects of postnatal malnutrition, installed at birth and maintained all through life in young and aged rats, on learning and memory of active avoidance, a task with an important procedural component. We now report that learning and long-term retention of this task were impaired in young malnourished animals, but not in young control, senile control, and senile malnourished Sprague-Dawley rats; young and senile rats were 90 and 660 days of age, respectively. Extinction tests showed, however, that long-term memory of the malnourished groups and senile control animals is impaired as compared with the young control animals. These data strongly suggest that the learning and long-term retention impairments seen in the young animals were due to postnatal malnutrition; in the senile groups, this cognitive alteration did not occur, probably because ageing itself is an important factor that enables the brain to engage in compensatory mechanisms that reduce the effects of malnutrition. Nonetheless, ageing and malnutrition, conditions known to produce anatomic and functional hippocampal alterations, impede the maintenance of long-term memory, as seen during the extinction test.
