25 research outputs found
Examining the contribution of histone modification to sex differences in learning and memory
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Examining the contribution of histone modification to sex differences in learning and memory
The epigenome serves as a signal integration platform that encodes information from experience and environment that adds tremendous complexity to the regulation of transcription required for memory, beyond the directions encoded in the genome. To date, our understanding of how epigenetic mechanisms integrate information to regulate gene expression required for memory is primarily obtained from male derived data despite sex-specific life experiences and sex differences in consolidation and retrieval of memory, and in the molecular mechanisms that mediate these processes. In this review, we examine the contribution of chromatin modification to learning and memory in both sexes. We provide examples of how exposure to a number of internal and external factors influence the epigenome in sex-similar and sex-specific ways that may ultimately impact transcription required for memory processes. We also pose a number of key open questions and identify areas requiring further investigation as we seek to understand how histone modifying mechanisms shape memory in females
Data from: Variation in home-field advantage and ability in leaf litter decomposition across successional gradients
1. It is increasingly recognized that interactions between plants and soil (a)biotic conditions can influence local decomposition processes. For example, decomposer communities may become specialized in breaking down litter of plant species that they are associated with, resulting in accelerated decomposition, known as ‘home-field advantage’ (HFA). Also, soils can vary inherently in their capacity to degrade organic compounds, known as ‘ability’. However, we have a poor understanding how environmental conditions drive the occurrence of HFA and ability. 2. Here, we studied how HFA and ability change across three types of successional gradients: coastal sand dunes (primary succession), inland drift sands (primary succession), and ex-arable fields (secondary succession). Across these gradients, litter quality (i.e., nutrient, carbon and lignin contents) increases with successional time for coastal dunes and decreases for the other two gradients. 3. We performed a 12-month reciprocal litter transplant experiment under greenhouse conditions using soils and litters collected from early-, mid-, and late-successional stages of each gradient. 4. We found that HFA and ability did not consistently shift with successional stage for all gradients, but were instead specific for each type of successional gradient. In coastal dunes HFA was positive for early-successional litter, in drift sands it was negative for mid-successional litter, and for ex-arable fields, HFA increased with successional time. Ability of decomposer communities was highest in mid-successional stages for coastal dunes and drift sands, but for ex-arable fields ability decreased throughout with successional time. High HFA was related to high litter C content and soil and organic matter content in soils and to low litter and soil nutrient concentrations. Ability did not consistently occur in successional stages with high or low litter quality. 5. Synthesis: Our findings show that specific environmental conditions, such as changes in litter or soil quality, along environmental gradients can shape the influence of HFA and ability on decomposition. In sites with strong HFA or ability, interactions between plants, litter and decomposer communities will be important drivers of nutrient cycling and hence have the potential to feedback to plant growth
Variation in home-field advantage and ability in leaf litter decomposition across successional gradients
It is increasingly recognized that interactions between plants and soil (a)biotic conditions can influence local decomposition processes. For example, decomposer communities may become specialized in breaking down litter of plant species that they are associated with, resulting in accelerated decomposition, known as "home-field advantage" (HFA). Also, soils can vary inherently in their capacity to degrade organic compounds, known as "ability." However, we have a poor understanding how environmental conditions drive the occurrence of HFA and ability. Here, we studied how HFA and ability change across three types of successional gradients: coastal sand dunes (primary succession), inland drift sands (primary succession) and ex-arable fields (secondary succession). Across these gradients, litter quality (i.e. nutrient, carbon and lignin contents) increases with successional time for coastal dunes and decreases for the other two gradients. We performed a 12-months reciprocal litter transplant experiment under greenhouse conditions using soils and litters collected from early-, mid- and late-successional stages of each gradient. We found that HFA and ability did not consistently shift with successional stage for all gradients, but were instead specific for each type of successional gradient. In coastal dunes, HFA was positive for early-successional litter, in drift, sands it was negative for mid-successional litter, and for ex-arable fields, HFA increased with successional time. Ability of decomposer communities was highest in mid-successional stages for coastal dunes and drift sands, but for ex-arable fields, ability decreased throughout with successional time. High HFA was related to high litter C content and soil and organic matter content in soils and to low litter and soil nutrient concentrations. Ability did not consistently occur in successional stages with high or low litter quality. Synthesis. Our findings show that specific environmental conditions, such as changes in litter or soil quality, along environmental gradients can shape the influence of HFA and ability on decomposition. In sites with strong HFA or ability, interactions between plants, litter and decomposer communities will be important drivers of nutrient cycling and hence have the potential to feedback to plant growth. A plain language summary is available for this article.</p
Systemic administration of the neurotensin NTS₁-receptor agonist PD149163 improves performance on a memory task in naturally deficient male Brown Norway rats.
Data from: Variation in home-field advantage and ability in leaf litter decomposition across successional gradients
1. It is increasingly recognized that interactions between plants and soil (a)biotic conditions can influence local decomposition processes. For example, decomposer communities may become specialized in breaking down litter of plant species that they are associated with, resulting in accelerated decomposition, known as ‘home-field advantage’ (HFA). Also, soils can vary inherently in their capacity to degrade organic compounds, known as ‘ability’. However, we have a poor understanding how environmental conditions drive the occurrence of HFA and ability. 2. Here, we studied how HFA and ability change across three types of successional gradients: coastal sand dunes (primary succession), inland drift sands (primary succession), and ex-arable fields (secondary succession). Across these gradients, litter quality (i.e., nutrient, carbon and lignin contents) increases with successional time for coastal dunes and decreases for the other two gradients. 3. We performed a 12-month reciprocal litter transplant experiment under greenhouse conditions using soils and litters collected from early-, mid-, and late-successional stages of each gradient. 4. We found that HFA and ability did not consistently shift with successional stage for all gradients, but were instead specific for each type of successional gradient. In coastal dunes HFA was positive for early-successional litter, in drift sands it was negative for mid-successional litter, and for ex-arable fields, HFA increased with successional time. Ability of decomposer communities was highest in mid-successional stages for coastal dunes and drift sands, but for ex-arable fields ability decreased throughout with successional time. High HFA was related to high litter C content and soil and organic matter content in soils and to low litter and soil nutrient concentrations. Ability did not consistently occur in successional stages with high or low litter quality. 5. Synthesis: Our findings show that specific environmental conditions, such as changes in litter or soil quality, along environmental gradients can shape the influence of HFA and ability on decomposition. In sites with strong HFA or ability, interactions between plants, litter and decomposer communities will be important drivers of nutrient cycling and hence have the potential to feedback to plant growth
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Exercise opens a temporal window for enhanced cognitive improvement from subsequent physical activity
The beneficial effects of exercise on cognition are well established; however specific exercise parameters regarding the frequency and duration of physical activity that provide optimal cognitive health have not been well defined. Here, we explore the effects of the duration of exercise and sedentary periods on long-term object location memory (OLM) in mice. We use a weak object location training paradigm that is subthreshold for long-term memory formation in sedentary controls, and demonstrate that exercise enables long-term memories to form. We show that 14- and 21-d of running wheel access enables mice to discriminate between familiar and novel object locations after a 24 h delay, while 2- or 7-d running wheel access provides insufficient exercise for such memory enhancement using the subthreshold learning paradigm. After 14- and 21-d of wheel running, exercise-induced cognitive enhancement then decays back to baseline performance following 3-d of sedentary activity. However, exercise-induced cognitive enhancement can be reactivated by an additional period of just 2 d exercise, previously shown to be insufficient to induce cognitive enhancement on its own. The reactivating period of exercise is capable of enhancing memory after three- or seven-sedentary days, but not 14-d. These data suggest a type of "molecular memory" for the exercise stimulus, in that once exercise duration reaches a certain threshold, it establishes a temporal window during which subsequent low-level exercise can capitalize on the neurobiological adaptations induced by the initial period of exercise, enabling it to maintain the benefits on cognitive function. These findings provide new information that may help to guide future clinical studies in exercise
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Aging mice show impaired memory updating in the novel OUL updating paradigm
Memories do not persist in a permanent, static state but instead must be dynamically modified in response to new information. Although new memory formation is typically studied in a laboratory setting, most real-world associations are modifications to existing memories, particularly in the aging, experienced brain. To date, the field has lacked a simple behavioral paradigm that can measure whether original and updated information is remembered in a single test session. To address this gap, we have developed a novel memory updating paradigm, called the Objects in Updated Locations (OUL) task that is capable of assessing memory updating in a non-stressful task that is appropriate for both young and old rodents. We first show that young mice successfully remember both the original memory and the updated information in OUL. Next, we demonstrate that intrahippocampal infusion of the protein synthesis inhibitor anisomycin disrupts both the updated information and the original memory at test, suggesting that memory updating in OUL engages the original memory. To verify this, we used the Arc CatFISH technique to show that the OUL update session reactivates a largely overlapping set of neurons as the original memory. Finally, using OUL, we show that memory updating is impaired in aging, 18-m.o. mice. Together, these results demonstrate that hippocampal memory updating is impaired with aging and establish that the OUL paradigm is an effective, sensitive method of assessing memory updating in rodents