A retrieval-specific mechanism of adaptive forgetting in the mammalian brain

Forgetting is a ubiquitous phenomenon that is actively promoted in many species. How and whether organisms’ behavioral goals drive which memories are actively forgotten is unknown. Here we show that processes essential to controlling goal-directed behavior trigger active forgetting of distracting memories that interfere with behavioral goals. When rats need to retrieve particular memories to guide exploration, it reduces later retention of other memories encoded in that environment. As with humans, this retrieval-induced forgetting is competition-dependent, cue-independent and reliant on prefrontal control: Silencing the medial prefrontal cortex with muscimol abolishes the effect. cFos imaging reveals that prefrontal control demands decline over repeated retrievals as competing memories are forgotten successfully, revealing a key adaptive benefit of forgetting. Occurring in 88% of the rats studied, this finding establishes a robust model of how adaptive forgetting harmonizes memory with behavioral demands, permitting isolation of its circuit, cellular and molecular mechanisms.Fil: Bekinschtein, Pedro Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Weisstaub, Noelia V.. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Gallo, Francisco Tomás. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Renner, Maria. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Anderson, Michael C.. University of Cambridge; Estados Unido

5-HT2a receptor in mPFC influences context-guided reconsolidation of object memory in perirhinal cortex

Context-dependent memories may guide adaptive behavior relaying in previous experience while updating stored information through reconsolidation. Retrieval can be triggered by partial and shared cues. When the cue is presented, the most relevant memory should be updated. In a contextual version of the object recognition task, we examined the effect of medial PFC (mPFC) serotonin 2a receptor (5-HT2aR) blockade during retrieval in reconsolidation of competing objects memories. We found that mPFC 5-HT2aR controls retrieval and reconsolidation of object memories in the perirhinal cortex (PRH), but not in the dorsal hippocampus in rats. Also, reconsolidation of objects memories in PRH required a functional interaction between the ventral hippocampus and the mPFC. Our results indicate that in the presence of conflicting information at retrieval, mPFC 5-HT2aR may facilitate top-down context-guided control over PRH to control the behavioral response and object memory reconsolidation.Fil: Morici, Juan Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Miranda, Magdalena. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Gallo, Francisco Tomás. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Zanoni Saad, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad Favaloro; ArgentinaFil: Bekinschtein, Pedro Alejandro. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Weisstaub, Noelia V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentin

Role of 5-HT2A Receptor in Social Cognition in Mice

The serotonergic system and more precisely the serotonin type 2Areceptor (5-HT2AR) is involved in a wide variety of cognitive and emotionalfunctions. In recent studies, it has been found that 5-HT2AR participates inthe prosocial effects of certain drugs. Moreover, the social cognitiveimpairments observed in different psychiatric disorders, such as schizophreniaand Asperger syndrome, have been associated with a hypofunction of the 5-HT2AR.However, the mechanisms underlying this phenotype remain unclear. In thepresent study we analyzed the role of 5-HT2AR in social preference (SP) using agenetically modified mouse model that presents a constitutive depletion ofthe5-HT2AR (KO) compared with their wild type mates (WT). For this purpose weperformed a three-chamber sociability test. We also explore how SP can beaffected by an increased level of serotonin in the central nervous system viachronic administration of fluoxetine. We observed that both male and female KOmice had a lower social preference compared to WT. Thus, the chronicadministration of fluoxetine increased social preference only in WT mice. Theseresults suggest that the serotonergic system could be involved in SP and thatits participation could mediated at least partially by 5-HT2AR.Fil: Sacson, Agostina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Morici, Juan Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Bekinschtein, Pedro Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Weisstaub, Noelia V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaXXXIV Anual Meeting of Argentine Society for Research in NeurosciencesCarlos PazArgentinaSociedad Argentina de Neurociencia

Hippocampal-Prefrontal cortex network dynamics predict performance during retrieval in a context-guided object memory task

Remembering life episodes is a complex process that requires the interaction between multiple brain areas. It is thought that contextual information provided by the hippocampus (HPC) can trigger the recall of a past event through the activation of medial prefrontal cortex (mPFC) neuronal ensembles, but the underlying mechanisms remain poorly understood. Indeed, little is known about how the vHPC and mPFC are coordinated during a contextual-guided recall of an object recognition memory. To address this, we performed electrophysiological recordings in behaving rats during the retrieval phase of the object-in-context memory task (OIC). Coherence, phase locking and theta amplitude correlation analysis showed an increase in vHPC-mPFC LFP synchronization in the theta range when animals explore contextually mismatched objects. Moreover, we identified ensembles of putative pyramidal cells in the mPFC that encode specific object-context associations. Interestingly, the increase of vHPC-mPFC synchronization during exploration of the contextually mismatched object and the preference of mPFC incongruent object neurons predicts the animals’ performance during the resolution of the OIC task. Altogether, these results identify changes in vHPC-mPFC synchronization and mPFC ensembles encoding specific object-context associations likely involved in the recall of past events.Fil: Morici, Juan Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Weisstaub, Noelia Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Zold, Camila Lidia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentin

Indicadores de Lactancia Materna obtenidos en el momento de la vacunación en cuatro Centros de Salud Familiar de la zona Sur de Santiago

ResumenObjetivosComparar datos oficiales de lactancia materna (LM) con los obtenidos por entrevistas realizadas en vacunaciones regulares.Sujetos y métodoSe realizó un estudio descriptivo, con muestreo por conveniencia, en el que se entrevistó a los tutores de los niños que asistieron a vacunarse en 4 Centros de Salud Familiar (Cesfam) del sur de Santiago. Se calcularon la prevalencia de los indicadores de LM y se estratificaron por edad y escolaridad de las madres. Comparamos los resultados con los informados en los REM de cada Cesfam utilizando Chi cuadrado (p<0,05).ResultadosAnalizamos 1.990 casos; la prevalencia de LME fue 43,4%, 34,2% y 8,8% a los 2, 4 y 6 meses respectivamente. La prevalencia de LME, informada por los REM, al sexto mes (41%) es significativamente mayor (p<0,001). Las madres con escolaridad inferior a 12 años tienen una prevalencia menor de la LME al 4.° mes que las de mayor escolaridad (28,4% vs 37,8% respectivamente, p<0,05).ConclusionesLas prevalencias de LME obtenidas en el momento de la vacunación son llamativamente menores a las estadísticas oficiales. Estas diferencias podrían deberse a que este estudio incluye población que no asiste habitualmente a control sano y a que la información de los REM es obtenida por el mismo profesional responsable de la promoción de la LM, lo que podría distorsionar las respuestas. Nuevos estudios son necesarios para mejorar la metodología utilizada para evaluar los indicadores de LM.AbstractObjectivesTo compare official breastfeeding (BF) data with those obtained by interviews conducted during regular vaccination visits.Subjects and methodA pilot descriptive study with convenience sampling was conducted by interviewing guardians of children attending vaccination in four Primary Care Centres in south Santiago. BF prevalence indicators were calculated and stratified by age and education of mothers. A comparison was made between the results and the official ones reported by each Centre. Chi-squared (X2) was calculated to evaluate differences (P<.05)ResultsA total of 1990 cases were analysed, in which exclusive BF prevalence was 43.4%, 34.2% and 8.8%, at 2, 4, and 6 months, respectively. At the sixth month, official data (41%) was significantly higher (P<.001). Mothers with less than 12 years of schooling have a lower prevalence of exclusive BF at the 4th month than those with higher education (28.4% vs 37.8%, respectively, P<.05).ConclusionsEven considering the small size of the sample studied, exclusive BF prevalence obtained is surprisingly lower than official reported data. That difference might be explained by: a) children brought to vaccinations are roughly two fold the number brought to well-child clinics and, b) potential bias in official data obtained by staff in charge of promotion and education on BF practices, which could distort the results. Further studies are needed to improve the methodology for collecting and analysis BF data

Medial prefrontal cortex role in recognition memory in rodents

The study of the neurobiology of recognition memory, defined by the integration of the different components of experiences that support recollection of past experiences have been a challenge for memory researches for many years. In the last twenty years, with the development of the spontaneous novel object recognition task and all its variants this has started to change. The features of recognition memory include a particular object or person ("what"), the context in which the experience took place, which can be the arena itself or the location within a particular arena ("where") and the particular time at which the event occurred ("when"). This definition instead of the historical anthropocentric one allows the study of this type of episodic memory in animal models. Some forms of recognition memory that require integration of different features recruit the medial prefrontal cortex. Focusing on findings from spontaneous recognition memory tasks performed by rodents, this review concentrates on the description of previous works that have examined the role that the medial prefrontal cortex has on the different steps of recognition memory. We conclude that this structure, independently of the task used, is required at different memory stages when the task cannot be solved by a single item strategy.Fil: Morici, Juan Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Bekinschtein, Pedro Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Weisstaub, Noelia V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentin

La escuela como formadora de hábitos alimentarios a través de los comedores escolares : un estado del arte

La falta de seguridad alimentaria, producto de la actual fase del capitalismo, afecta principalmente a las familias que destinan a la comida la mayor parte de sus ingresos. Como resultado, los niños pertenecientes a esas familias, están más expuestos a padecer obesidad, sobrepeso y a no recibir una alimentación que garantice su derecho a la salud, presente y futura. Si bien es principalmente en la familia donde se desarrollan las pautas alimentarias, el placer, el gusto y el rechazo por distintos alimentos, por distintos factores, muchas familias se ven impelidas en la actualidad a completar la alimentación de sus hijos a través de los comedores escolares. En situaciones de pobreza, la escuela pública contribuye a enfrentar situaciones de vulnerabilidad alimenticia. Los sectores medios y altos, en tanto, depositan cada vez más en las escuelas de doble escolaridad la responsabilidad por el almuerzo de los hijos. En momentos en que la obesidad infantil, sin distingo de países, avanza de modo alarmante, se valora que los comedores escolares y la escuela como institución educativa, pueden contribuir a disminuir el sobrepeso en la edad adulta. De allí que muchos estudios han empezado a poner foco en qué comen y cómo comen los niños en escuela, tema hasta ahora, poco problematizado en nuestro medio. El propósito de esta ponencia es presentar un estado del arte sobre el papel de los comedores escolares y sus efectos sobre las prácticas alimentarias de los niños así como las posibles interacciones entre alimentación escolar y promoción de hábitos alimentarios y de comensalidad con potencialidades para prevenir la obesidad infantil.Fil: Bustos, Rosa María . Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Illobre, Graciela . Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Molina, Cecilia . Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Weisstaub, Sergio G. . Universidad de Chil

Advertencias octogonales en los sucedáneos de leche materna: una herramienta para promover una alimentación infantil informada

.Sr. Editor, La alimentación y nutrición saludable durante los primeros años de vida es esencial para garantizar un adecuado crecimiento y desarrollo. Vale la pena recordar que el primer alimento que debe recibir un niño es la leche materna, dado los múltiples beneficios que tiene para los niños, las madres y la sociedad. Uno de los efectos importantes que a largo plazo tiene la ali-mentación con leche materna es la disminución del riesgo de algunas enfermedades crónicas

Effects of the intake of white wheat bread added with garlic and resistant starch: action on calcium bioavailability and metabolic parameters of growing Wistar rats

Wheat bread is a widely consumed food and is suitable for the introduction of functional ingredients. The aim of this work was to study the effects of bread with garlic and resistant starch as a fiber source on physiological, metabolic, and functional parameters using an in vivo Wistar rat model. Rats were fed with three diets: a control diet prepared according to the American Institute of Nutrition (C), and two semisynthetic diets containing wheat bread (B) and wheat bread with garlic, resistant starch and calcium citrate (BGR). Fresh feces were weighed and lactobacilli (L) and Enterobacteriaceae (E) were analyzed at different times: 1, 20, 45 and 60 days. The pH of the caecal content was recorded and at the end of the study changes in the bone mineral density of total skeleton (ts BMD), femur (F-BMD), spine (S-BMD) and tibia (T-BMD) were determined. Lipoprotein profile was assessed, atherogenic indexes were calculated and malonaldehyde content was measured in the serum and liver. In relation to gut microbiota, the BGR group showed an increase in the L/E ratio with respect to the other groups which was correlated with a lower cecal pH. Besides, the BGR group presented lower weight and a more favourable metabolic profile. In relation to bone measurements, the BGR group presented higher values of ts BMC, ts BMD, F-BMD, and T-BMD than the B group. Thus, bread with resistant starch, garlic and calcium citrate showed a prebiotic effect increasing calcium bioavailability and deposition in bones, compared with wheat bread. The observed beneficial health effects allow us to consider the design of healthier breads.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Effects of the intake of white wheat bread added with garlic and resistant starch: action on calcium bioavailability and metabolic parameters of growing Wistar rats

Wheat bread is a widely consumed food and is suitable for the introduction of functional ingredients. The aim of this work was to study the effects of bread with garlic and resistant starch as a fiber source on physiological, metabolic, and functional parameters using an in vivo Wistar rat model. Rats were fed with three diets: a control diet prepared according to the American Institute of Nutrition (C), and two semisynthetic diets containing wheat bread (B) and wheat bread with garlic, resistant starch and calcium citrate (BGR). Fresh feces were weighed and lactobacilli (L) and Enterobacteriaceae (E) were analyzed at different times: 1, 20, 45 and 60 days. The pH of the caecal content was recorded and at the end of the study changes in the bone mineral density of total skeleton (ts BMD), femur (F-BMD), spine (S-BMD) and tibia (T-BMD) were determined. Lipoprotein profile was assessed, atherogenic indexes were calculated and malonaldehyde content was measured in the serum and liver. In relation to gut microbiota, the BGR group showed an increase in the L/E ratio with respect to the other groups which was correlated with a lower cecal pH. Besides, the BGR group presented lower weight and a more favourable metabolic profile. In relation to bone measurements, the BGR group presented higher values of ts BMC, ts BMD, F-BMD, and T-BMD than the B group. Thus, bread with resistant starch, garlic and calcium citrate showed a prebiotic effect increasing calcium bioavailability and deposition in bones, compared with wheat bread. The observed beneficial health effects allow us to consider the design of healthier breads.Centro de Investigación y Desarrollo en Criotecnología de Alimento