RESUMEN
According to the alternative prey hypothesis (APH), the temporal synchrony in population fluctuations of microtine rodents and other small herbivores in boreal areas is caused by generalist predators with numerical and functional response to microtines, leading to an increased predation of prey alternative to microtines in the low phase of the microtine population fluctuations. The tree-climbing pine marten (Martes martes) is a food generalist that includes bird eggs among its alternative prey, also eggs of the cavity-nesting common goldeneye (Bucephala clangula). We used long-term data to test whether pine marten predation of goldeneye eggs in nest boxes varied as predicted by the APH. As a measure of microtine abundance at the time of nesting, we applied two measures. First, for goldeneye nests located <40 km from our microtine trapping site, we applied the trapping index of microtine rodents. Second, to also use data from nests located >40 km from our microtine trapping site, and from nests in years when trapping was not conducted, we used two proxies for the microtine abundance: whether boreal owls (Aegolius funereus) nested in any of our boxes <40 km from each goldeneye nest and the average clutch size of these boreal owls. The probability of predation of a goldeneye nest was independent of the microtine trapping index and independent of the proxies for microtine abundance. However, it increased with cavity age, taken as the number of nesting seasons elapsed since the actual nest box was installed, and declined with distance from habitat with forest canopy. The effect of cavity age confirms that the long-term spatial memory of pine marten is an important factor in the pattern of its predation on nests in tree cavities.
RESUMEN
The alternative prey hypothesis (APH) states that temporally synchronous population fluctuations of microtine rodents and other small herbivores are caused by generalist predators that show functional and numerical responses to the abundance of microtines. This would lead to an increased predation of alternative prey in the low phase of the microtine population fluctuations. One candidate for such a predator is the tree-climbing pine marten (Martes martes), which includes bird eggs in its diet, among them eggs of the cavity-nesting boreal owl (Aegolius funereus). I used long-term data to test whether pine marten predation of boreal owl eggs in nest boxes varied as predicted by the APH. The probability of predation of owl nests situated < 45 km from a site where microtines were trapped in spring during four decades increased with microtine trapping index, which is opposite to the prediction from the APH. As the data set was limited to one nest per box, I extended it spatially and temporally using the clutch size of each boreal owl nest as a proxy for the actual microtine abundance at the site. The probability of nest predation increased with clutch size. However, the effects of microtine index and owl clutch size became non-significant when I controlled for habitat, and in particular cavity age, which had an overriding effect. The increase in predation probability with cavity age suggests that the long-term spatial memory of pine marten is an important factor in the pattern of its nest predation in tree cavities.
Asunto(s)
Mustelidae , Estrigiformes , Animales , Arvicolinae , Comportamiento de Nidificación/fisiología , Conducta Predatoria/fisiología , TaigaRESUMEN
ATRX gene mutations have been identified in syndromic and non-syndromic intellectual disabilities in humans. ATRX is known to maintain genomic stability in neuroprogenitor cells, but its function in differentiated neurons and memory processes remains largely unresolved. Here, we show that the deletion of neuronal Atrx in mice leads to distinct hippocampal structural defects, fewer presynaptic vesicles, and an enlarged postsynaptic area at CA1 apical dendrite-axon junctions. We identify male-specific impairments in long-term contextual memory and in synaptic gene expression, linked to altered miR-137 levels. We show that ATRX directly binds to the miR-137 locus and that the enrichment of the suppressive histone mark H3K27me3 is significantly reduced upon the loss of ATRX. We conclude that the ablation of ATRX in excitatory forebrain neurons leads to sexually dimorphic effects on miR-137 expression and on spatial memory, identifying a potential therapeutic target for neurological defects caused by ATRX dysfunction.
Asunto(s)
Eliminación de Gen , Regulación de la Expresión Génica , Trastornos de la Memoria/genética , Trastornos de la Memoria/fisiopatología , MicroARNs/genética , Caracteres Sexuales , Aprendizaje Espacial , Proteína Nuclear Ligada al Cromosoma X/deficiencia , Animales , Secuencia de Bases , Región CA1 Hipocampal/patología , Región CA1 Hipocampal/ultraestructura , Condicionamiento Operante , Dendritas/metabolismo , Dendritas/ultraestructura , Femenino , Genotipo , Histonas/metabolismo , Lisina/metabolismo , Imagen por Resonancia Magnética , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , MicroARNs/metabolismo , Neuronas , Especificidad de Órganos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Sinapsis/metabolismo , Sinapsis/ultraestructura , Proteína Nuclear Ligada al Cromosoma X/metabolismoRESUMEN
The ability of an animal to integrate and retain spatial information of resources often depends on the spatial memory and the speed at which this memory crystallizes. These become especially important once foragers reach their target area. However, very little is known about how wild common marmosets encode spatial information when feeding rewards are near to each other in a small-scale space. With this in mind, we performed field experiments to test foraging decisions related to a small-scale space setting. Specifically, we tested the (i) short- and (ii) long-term spatial memory, as well as (iii) the ability to remember the spatial location of resources after a single visit (one-trial spatial learning). The study was conducted with four groups of wild common marmosets (Callithrix jacchus) living in a semiarid Caatinga environment. We observed that individuals were able to retain spatial information of food sources on both a short- and long-term basis and to learn the spatial location of these resources after a single visit. We suggest that such abilities during foraging can improve the search for scattered resources with fluctuations of food availability. Presumably, this would be particularly advantageous in Caatinga, with its vegetation exhibiting asynchronous phenological patterns. Altogether, our results demonstrate that common marmosets employ all three studied spatial cognitive abilities to improve their food search and consumption.
Asunto(s)
Conducta Apetitiva , Callithrix/fisiología , Memoria Espacial , Animales , Conducta Animal , Brasil , Femenino , Masculino , Memoria a Largo Plazo , Memoria a Corto Plazo , Conducta SocialRESUMEN
Studying the non-motor disorders of the prodromal phase of Parkinson's disease (PD) is of great importance because of their negative impact on patient's quality of life. Classical neurotoxic animal models of PD generally unable the exploration of the progression of the non-motor phase of the prodromal stage of the disease. The aim of this study is to assess the evolution of two types of memory alteration namely; short working and spatial memories at different stages of the prodromal phase of a rat model of PD, using repetitive reserpine administration at low dose. The study was carried out in rat with repeated i.p reserpine administration (0.2â¯mg/kg/day) during 13 days. Working memory was assessed by the Novel Object Recognition test (NOR) and the T-maze, while spatial memory was assessed by Morris Water maze (MWM) at to stages (7days and 13days) of prodromal phase of the disease. By means of immunohistochemistry, the serotonergic innervation of the Baso-Lateral Amygdala nucleus (BLA) as well as the morphological changes of astroglia within hippocampus (using anti-GFAP marker) were examined at the latest stage (13days) of the disease. Our data show a differential deterioration of short-term working memory without the long-term spatial memory being changed which was accompanied by a significant decrease in serotonin innervation of the BLA and a striking change in both density and morphology of the astrocyte at the level of the hippocampus. The present study has brought evidence of an early deficit of short working memory rather than spatial memory deficit which seems to be intact even at the latest stage of the prodromal phase of PD. Such deficit could arise from the loss of 5-HT innervation in BLA and/or the astroglial morpho-functional changes within the hippocampus leading to possible neurophysiological disturbances of the different neighboring neuronal populations involved in short working memory.
Asunto(s)
Memoria a Corto Plazo/fisiología , Memoria Espacial/fisiología , Amígdala del Cerebelo/fisiopatología , Animales , Astrocitos/patología , Encéfalo/fisiopatología , Modelos Animales de Enfermedad , Hipocampo/fisiopatología , Masculino , Trastornos de la Memoria/fisiopatología , Enfermedad de Parkinson/fisiopatología , Corteza Prefrontal/fisiopatología , Síntomas Prodrómicos , Calidad de Vida , Ratas , Reserpina/farmacología , Percepción VisualRESUMEN
Many works have been performed to understand the mechanisms of the formation and persistence of memory. However, it is not fully understood whether the decay of long-term memory can be modulated by the activation of dopamine D1 receptor. A Barnes maze task was employed to measure long-term spatial memory. We observed that the spatial memory acquired through 3 trials per session for 4â¯days had begun to fade out by the 14th day and had completely disappeared by 21â¯days after the first probe test. The intraperitoneal administration of SKF 38393 (a dopamine D1 receptor agonist) for 7â¯days beginning on the 14th day after the first probe test prevented natural memory forgetting, and the intraperitoneal administration of SCH 23390 (a dopamine D1 receptor antagonist) prevented this memory persistence. In the Western blotting, the administration of SKF 38393 increased the phosphorylation levels of PKA, ERK1/2, CaMKII, and CREB in the hippocampus. In addition, such increased levels were decreased by the corresponding antagonist (SCH 23390). Moreover, the inhibition of PKA could completely reverse the preservation of spatial memory induced by dopamine D1 receptor activation. These results suggest that the activation of the dopamine D1 receptor plays a critical role in the persistence of long-term spatial memory through the PKA signaling pathway.
Asunto(s)
Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Hipocampo/metabolismo , Memoria a Largo Plazo/fisiología , Receptores de Dopamina D1/metabolismo , Memoria Espacial/fisiología , 2,3,4,5-Tetrahidro-7,8-dihidroxi-1-fenil-1H-3-benzazepina/administración & dosificación , Animales , Agonistas de Dopamina , Masculino , Aprendizaje por Laberinto/fisiología , Ratones , Transducción de SeñalRESUMEN
Little is known about the long-term effects of chronic exposure to low-level organophosphate (OP) pesticides, and the role of neurotransmitter systems, other than the cholinergic system, in mediating OP neurotoxicity. In this study, rats were administered 5mg/kg/day of chlorpyrifos (CPF) for 6 months commencing at 3-months-of-age. The animals were examined 7 months later (at 16-months-of-age) for spatial learning and memory in the Morris water maze (MWM) and locomotor activity. In addition, we assessed the chronic effects of CPF on glutamatergic and gamma-aminobutyric acid (GABAergic) function using pharmacological challenges with dizocilpine (MK801) and diazepam. Impaired performance related to altered search patterns, including thigmotaxis and long-term spatial memory was noted in the MWM in animals exposed to CPF, pointing to dietary CPF-induced behavioral disturbances, such as anxiety. Twenty-four hours after the 31st session of repeated acquisition task, 0.1mg/kg MK801, an N-methyl-d-aspartate (NMDA) antagonist was intraperitoneally (i.p.) injected for 4 consecutive days. Decreased latencies in the MWM in the control group were noted after two sessions with MK801 treatment. Once the MWM assessment was completed, animals were administered 0.1 or 0.2mg/kg of MK801 and 1 or 3mg/kg of diazepam i.p., and tested for locomotor activity. Both groups, the CPF dietary and control, displayed analogous performance in motor activity. In conclusion, our data point to a connection between the long-term spatial memory, thigmotaxic response and CPF long after the exposure ended.