When Are New Hippocampal Neurons, Born in the Adult Brain, Integrated into the Network That Processes Spatial Information?

Adult-born neurons in the dentate gyrus (DG) functionally integrate into the behaviorally relevant hippocampal networks, showing a specific Arc-expression response to spatial exploration when mature. However, it is not clear when, during the 4- to 6-week interval that is critical for survival and maturation of these neurons, this specific response develops. Therefore, we characterized Arc expression after spatial exploration or cage control conditions in adult-born neurons from rats that were injected with BrdU on one day and were sacrificed 1, 7, 15, 30, and 45 days post-BrdU injection (PBI). Triple immunostaining for NeuN, Arc, and BrdU was analyzed through the different DG layers. Arc protein expression in BrdU-positive cells was observed from day 1 to day 15 PBI but was not related to behavioral stimulation. The specific Arc-expression response to spatial exploration was observed from day 30 and 45 in about 5% of the BrdU-positive cell population. Most of the BrdU-positive neurons expressing Arc in response to spatial exploration (∼90%) were located in DG layer 1, and no Arc expression was observed in cells located in the subgranular zone (SGZ). Using the current data and that obtained previously, we propose a mathematical model suggesting that new neurons are unlikely to respond to exploration by expressing Arc after they are 301 days old, and also that in a 7-month-old rat the majority (60%) of the neurons that respond to exploration must have been born during adulthood; thus, suggesting that adult neurogenesis in the DG is highly relevant for spatial information processing

Long-term cognitive effects of human stem cell transplantation in the irradiated brain

PURPOSE: Radiotherapy remains a primary treatment modality for the majority of central nervous system tumors, but frequently leads to debilitating cognitive dysfunction. Given the absence of satisfactory solutions to this serious problem, we have used human stem cell therapies to ameliorate radiation-induced cognitive impairment. Here, past studies have been extended to determine whether engrafted cells provide even longer-term benefits to cognition. MATERIALS AND METHODS: Athymic nude rats were cranially irradiated (10 Gy) and subjected to intrahippocampal transplantation surgery 2 days later. Human embryonic stem cells (hESC) or human neural stem cells (hNSC) were transplanted, and animals were subjected to cognitive testing on a novel place recognition task 8 months later. RESULTS: Grafting of hNSC was found to provide long lasting cognitive benefits over an 8-month post-irradiation interval. At this protracted time, hNSC grafting improved behavioral performance on a novel place recognition task compared to irradiated animals not receiving stem cells. Engrafted hESC previously shown to be beneficial following a similar task, 1 and 4 months after irradiation, were not found to provide cognitive benefits at 8 months. CONCLUSIONS: Our findings suggest that hNSC transplantation promotes the long-term recovery of the irradiated brain, where intrahippocampal stem cell grafting helps to preserve cognitive function

Yeasts associated with the production of distilled alcoholic beverages

Distilled alcoholic beverages are produced firstly by fermenting sugars emanating from cereal starches (in the case of whiskies), sucrose-rich plants (in the case of rums), fructooligosaccharide-rich plants (in the case of tequila) or from fruits (in the case of brandies). Traditionally, such fermentations were conducted in a spontaneous fashion, relying on indigenous microbiota, including wild yeasts. In modern practices, selected strains of Saccharomyces cerevisiae are employed to produce high levels of ethanol together with numerous secondary metabolites (eg. higher alcohols, esters, carbonyls etc.) which greatly influence the final flavour and aroma characteristics of spirits following distillation of the fermented wash. Therefore, distillers, like winemakers, must carefully choose their yeast strain which will be very important in providing the alcohol content and the sensory profiles of spirit beverages. This Chapter discusses yeast and fermentation aspects associated with the production of selected distilled spirits and highlights similarities and differences with the production of wine

Orchestrated experience-driven Arc responses are disrupted in a mouse model of Alzheimer's disease

Experience-induced expression of immediate-early gene Arc/Arg3.1 is known to play a pivotal role in the consolidation of memory. Here we use in-vivo longitudinal multiphoton imaging to show orchestrated activity-dependent expression of Arc in the mouse extrastriate visual cortex in response to a structured visual stimulation. In wild-type mice, the amplitude of the Arc response in individual neurons strongly predicts the probability of reactivation by a subsequent presentation of the same stimulus. In a mouse model of Alzheimer’s disease, this association is markedly disrupted in the cortex specifically near senile plaques. Neurons in the vicinity of plaques are less likely to respond but, paradoxically, there is stronger response in those few neurons around plaques that do respond. To the extent that the orchestrated pattern of Arc expression reflects nervous system responses to, and physiological consolidation of, behavioral experience, the disruption in Arc patterns reveals plaque-associated interference with neural network integration

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Structural synaptic plasticity in the hippocampus induced by spatial experience and its implications in information processing

Introduction: Long-lasting memory formation requires that groups of neurons processing new information develop the ability to reproduce the patterns of neural activity acquired by experience. Development: Changes in synaptic efficiency let neurons organise to form ensembles that repeat certain activity patterns again and again. Among other changes in synaptic plasticity, structural modifications tend to be long-lasting which suggests that they underlie long-term memory. There is a large body of evidence supporting that experience promotes changes in the synaptic structure, particularly in the hippocampus. Conclusion: Structural changes to the hippocampus may be functionally implicated in stabilising acquired memories and encoding new information. Resumen: Introducción: Para formar memorias perdurables, es necesario que los grupos de neuronas encargados de procesar la información que adquirimos desarrollen la capacidad de reproducir los patrones de actividad que se forman a través de la experiencia. Desarrollo: Los cambios en la eficiencia sináptica permiten que las neuronas se organicen en «ensambles» y reproduzcan una y otra vez estos patrones de actividad. Entre los cambios en la eficiencia sináptica están las modificaciones en la estructura, las cuales tienden a perdurar por mucho tiempo y por ello se les vincula con la memoria a largo plazo. En la literatura existe amplia evidencia de que la experiencia promueve modificaciones en la estructura sináptica, particularmente en regiones como el hipocampo. Conclusión: Las implicaciones funcionales de estos cambios en el hipocampo incluyen un posible papel en la estabilización de los recuerdos adquiridos y en la codificación de nueva información. Keywords: Synaptic plasticity, Hippocampus, Spatial experience, Long-term memory, Neuronal ensembles, Mossy fibres, Palabras clave: Plasticidad sináptica, Hipocampo, Experiencia espacial, Memoria a largo plazo, Ensambles neuronales, Fibras musgosa

Plasticidad sináptica estructural en el hipocampo inducida por la experiencia espacial y sus implicaciones en el procesamiento de información

Resumen: Introducción: Para formar memorias perdurables, es necesario que los grupos de neuronas encargados de procesar la información que adquirimos desarrollen la capacidad de reproducir los patrones de actividad que se forman a través de la experiencia. Desarrollo: Los cambios en la eficiencia sináptica permiten que las neuronas se organicen en «ensambles» y reproduzcan una y otra vez estos patrones de actividad. Entre los cambios en la eficiencia sináptica están las modificaciones en la estructura, las cuales tienden a perdurar por mucho tiempo y por ello se les vincula con la memoria a largo plazo. En la literatura existe amplia evidencia de que la experiencia promueve modificaciones en la estructura sináptica, particularmente en regiones como el hipocampo. Conclusión: Las implicaciones funcionales de estos cambios en el hipocampo incluyen un posible papel en la estabilización de los recuerdos adquiridos y en la codificación de nueva información. Abstract: Introduction: Long-lasting memory formation requires that groups of neurons processing new information develop the ability to reproduce the patterns of neural activity acquired by experience. Development: Changes in synaptic efficiency let neurons organise to form ensembles that repeat certain activity patterns again and again. Among other changes in synaptic plasticity, structural modifications tend to be long-lasting which suggests that they underlie long-term memory. There is a large body of evidence supporting that experience promotes changes in the synaptic structure, particularly in the hippocampus. Conclusion: Structural changes to the hippocampus may be functionally implicated in stabilising acquired memories and encoding new information. Palabras clave: Plasticidad sináptica, Hipocampo, Experiencia espacial, Memoria a largo plazo, Ensambles neuronales, Fibras musgosas, Keywords: Synaptic plasticity, Hippocampus, Spatial experience, Long-term memory, Neuronal ensembles, Mossy fibre

Blockade of N-methyl-D-aspartate receptors in the insular cortex disrupts taste aversion and spatial memory formation

The present experiments examined the effects of direct intracortical microinjections of the N-methyl-D-aspartate receptor antagonist 2-amino-5-phosphonovaleric acid directly into the insular cortex of rats, before or immediately after training of conditioned taste aversion and the water maze spatial learning task. In the first series of experiments animals received bilateral injections of 2-amino-5-phosphonovaleric acid prior to taste aversion conditioning or spatial training. A strong disruptive effect was found in the acquisition of training tasks. To determine the possible involvement of N-methyl-D-aspartate receptors in the early post-training processes taking place in the cortex during both learning paradigms, in a second series of experiments, animals received bilateral 2-amino-5-phosphonovaleric acid microinjections 30, 60 or 120 min after the acquisition trial, and 15 min before the retention test. For spatial learning successive treatments were independently done either starting at the onset of the asymptotic phase of the learning curve, 0, 30 or 120 min after finishing the training session, as well as 15 min before the retention test trial. The conditioned taste aversion task remained sensitive to N-methyl-D-aspartate blockade during a period of at least 2 h after the first presentation of the gustatory stimulus, while in the case of the spatial learning task, a gradually decreasing effect was observed from the onset of the asymptotic phase onwards. Taken together, these results provide direct evidence for N-methyl-D-aspartate receptor involvement in cortical regulation of memory formation. Furthermore, our results suggest that in the same cortical region, a different time-course for the activation of N-methyl-D-aspartate-dependent mechanisms occurs during the early formation of cortically mediated memories, depending on the particular behavioural task

SAT0118 La calprotectina estratifica la actividad de la enfermedad mejor que los reactivos de fase aguda en pacientes con artritis reumatoide que reciben inhibidores del TNF

Background Calprotectin is a major S100 leucocyte protein, associated with disease activity in rheumatoid arthritis (RA) patients. Calprotectin is a potentially biomarker more sensitive of disease activity than conventional acute-phase reactans