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"Animal memory."
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Early evolution of human memory : great apes, tool-making, and cognition
This work examines the cognitive capacity of great apes in order to better understand early man and the importance of memory in the evolutionary process. It synthesizes research from comparative cognition, neuroscience, primatology as well as lithic archaeology, reviewing findings on the cognitive ability of great apes to recognize the physical properties of an object and then determine the most effective way in which to manipulate it as a tool to achieve a specific goal. The authors argue that apes (Hominoidea) lack the human cognitive ability of imagining how to blend reality, which requires drawing on memory in order to envisage alternative future situations, and thereby modifying behavior determined by procedural memory.
Book
Plant ecology meets animal cognition: impacts of animal memory on seed dispersal
We propose that an understanding of animal learning and memory is critical to predicting the impacts of animals on plant populations through processes such as seed dispersal, pollination and herbivory. Focussing on endozoochory, we review the evidence that animal memory plays a role in seed dispersal, and present a model which allows us to explore the fundamental consequences of memory for this process. We demonstrate that decision-making by animals based on their previous experiences has the potential to determine which plants are visited, which fruits are selected to be eaten from the plant and where seeds are subsequently deposited, as well as being an important determinant of animal survival. Collectively, these results suggest that the impact of animal learning and memory on seed dispersal is likely to be extremely important, although to date our understanding of these processes suffers from a conspicuous lack of empirical support. This is partly because of the difficulty of conducting appropriate experiments but is also the result of limited interaction between plant ecologists and those who work on animal cognition. We believe that an improved understanding of the effects of animal memory in endozoochorous interactions will allow better prediction of the impacts of ecosystem changes such as habitat fragmentation, introductions of novel species of plants and animals and reintroductions of animal populations to areas from which they have been extirpated, and hope that the ideas we put forward here provide an impetus for further work in this area.
Journal Article
Long-duration hippocampal sharp wave ripples improve memory
Hippocampal sharp wave ripples (SPW-Rs) have been hypothesized as a mechanism for memory consolidation and action planning. The duration of ripples shows a skewed distribution with a minority of long-duration events. We discovered that long-duration ripples are increased in situations demanding memory in rats. Prolongation of spontaneously occurring ripples by optogenetic stimulation, but not randomly induced ripples, increased memory during maze learning. The neuronal content of randomly induced ripples was similar to short-duration spontaneous ripples and contained little spatial information. The spike content of the optogenetically prolonged ripples was biased by the ongoing, naturally initiated neuronal sequences. Prolonged ripples recruited new neurons that represented either arm of the maze. Long-duration hippocampal SPW-Rs replaying large parts of planned routes are critical for memory.
Journal Article
Myelin degeneration and diminished myelin renewal contribute to age-related deficits in memory
Cognitive decline remains an unaddressed problem for the elderly. We show that myelination is highly active in young mice and greatly inhibited in aged mice, coinciding with spatial memory deficits. Inhibiting myelination by deletion of Olig2 in oligodendrocyte precursor cells impairs spatial memory in young mice, while enhancing myelination by deleting the muscarinic acetylcholine receptor 1 in oligodendrocyte precursor cells, or promoting oligodendroglial differentiation and myelination via clemastine treatment, rescues spatial memory decline during aging.Wang et al. show that myelination is greatly inhibited in aged brains. Enhancing myelination by ablation of M1R in OPCs or clemastine treatment promotes oligodendroglial differentiation and consequently rescues spatial memory decline during aging.
Journal Article
Assessment of spatial learning and memory in the Barnes maze task in rodents—methodological consideration
Among the methods valuable for assessing spatial learning and memory impairments in rodents, the Barnes maze (BM) task deserves special attention. It is based on the assumption that the animal placed into the aversive environment should learn and remember the location of an escape box located below the surface of the platform. Different phases of the task allow to measure spatial learning, memory retrieval, and cognitive flexibility. Herein, we summarize current knowledge about the BM procedure, its variations and critical parameters measured in the task. We highlight confounding factors which should be taken into account when conducting BM task, discussing briefly its advantages and disadvantages. We then propose an extended version of the BM protocol which allows to measure different aspects of spatial learning and memory in rodents. We believe that this review will help to standardize the BM methodology across the laboratories and eventually make the results comparable.
Journal Article
028 Sleep loss disrupts hippocampal memory consolidation via an acetylcholine- and somatostatin interneuron-mediated inhibitory gate
Introduction Sleep loss profoundly disrupts consolidation of hippocampus-dependent memory. To better characterize effects of learning and sleep loss on the hippocampal circuit, we quantified activity-dependent phosphorylation of ribosomal subunit S6 (pS6) across the dorsal hippocampus of mice. Methods We first measured pS6 throughout the hippocampus after learning (single trial contextual fear conditioning; CFC), and after subsequent sleep or sleep deprivation (SD). To characterize cell populations with activity affected by SD, we used translating ribosome affinity purification (TRAP)-seq to identify cell type-specific transcripts on pS6 ribosomes after SD vs. sleep. We next used pharmacogenetics to mimic the effects of SD, selectively activating hippocampal Sst+ interneurons or cholinergic inputs to hippocampus from the medial septum (MS) while mice slept in the hours following CFC. We also inhibited these neuronal populations to assess effects on memory consolidation. Results We find that pS6 in enhanced in the dentate gyrus (DG) following single-trial CFC, but is reduced throughout the hippocampus after brief SD – a manipulation which disrupts contextual fear memory (CFM) consolidation. Cell type-specific enrichment analysis (CSEA) of these transcripts revealed that hippocampal somatostatin-expressing (Sst+) interneurons, and cholinergic and orexinergic inputs to hippocampus, are selectively activated after SD. We used TRAP targeted to hippocampal Sst+ interneurons to identify cellular mechanisms mediating SD-driven Sst+ interneuron activation. . We find that activation of Sst+ interneurons is sufficient to disrupt CFM consolidation, by gating activity in surrounding pyramidal neurons, while inhibition of Sst+ interneurons enhances memory consolidation. Similarly, pharmacogenetic activation of cholinergic input to hippocampus from the MS disrupted CFM. Inhibition of MS cholinergic neurons promoted CFM consolidation and disinhibited neurons in the DG, increasing pS6 expression among DG granule cells. Conclusion Our data suggest that state-dependent gating of DG activity during SD is mediated by cholinergic input. Together these data provide evidence for an inhibitory gate on hippocampal information processing, which is activated by sleep loss. Support (if any) R01-NS118440 to SJA from NINDS, DP2-MH104119 to SJA from the NIH Director’s Office, and a Human Frontiers Science Program Young Investigator Award
Journal Article
Caspase-1 inhibition alleviates cognitive impairment and neuropathology in an Alzheimer’s disease mouse model
Alzheimer's disease (AD) is an intractable progressive neurodegenerative disease characterized by cognitive decline and dementia. An inflammatory neurodegenerative pathway, involving Caspase-1 activation, is associated with human age-dependent cognitive impairment and several classical AD brain pathologies. Here, we show that the nontoxic and blood–brain barrier permeable small molecule Caspase-1 inhibitor VX-765 dose-dependently reverses episodic and spatial memory impairment, and hyperactivity in the J20 mouse model of AD. Cessation of VX-765 results in the reappearance of memory deficits in the mice after 1 month and recommencement of treatment re-establishes normal cognition. VX-765 prevents progressive amyloid beta peptide deposition, reverses brain inflammation, and normalizes synaptophysin protein levels in mouse hippocampus. Consistent with these findings, Caspase-1 null J20 mice are protected from episodic and spatial memory deficits, neuroinflammation and Aβ accumulation. These results provide in vivo proof of concept for Caspase-1 inhibition against AD cognitive deficits and pathologies.
Caspase-1, activated by stress in immune cells and in CNS human neurons, may contribute to neuronal degeneration. Here, the authors investigate the therapeutic potential of a Caspase-1 inhibitor in a mouse model of Alzheimer’s disease.
Journal Article
0094 The Effect of Zolpidem on Sleep-Dependent Declarative Memory Consolidation
Abstract
Introduction
Sleep plays a critical role in memory consolidation. At the same time, about 20% of population in the U.S. suffer from sleep disorders or deprivation, and about 16% of them reported using sleep aids (CDC, 2015). However, the effect of sleep aids on sleep-dependent memory consolidation remains unclear. Previous studies have observed an improvement in sleep-dependent declarative memory consolidation with zolpidem over a daytime nap (Mednick et al., 2013). The current study investigates the effect of zolpidem on declarative memory consolidation over a night of sleep and over 24 hours.
Methods
This study employed a double-blind, placebo-controlled, within-subject design, in which every subject (N=26, 12 females) experienced both zolpidem and placebo. All subjects were healthy, college-aged adults without sleep disorder. A 32-channel electroencephalogram cap was used to record brain activity during sleep. Word paired-associates task was used to evaluate memory performance. Participants reported to the laboratory in the evening, performed word paired-associates task (test1), then ingested either zolpidem or placebo before sleep. They were tested on the task in the following morning (test2) as well as in the following evening (test3). Paired-sample t-tests for retrieval difference scores between placebo and zolpidem conditions were conducted.
Results
Participants showed similar baseline performance on the word paired-associates task (test 1, p=0.45). Zolpidem condition showed higher memory retention compared to placebo 24hr after drug ingestion (test3-test1, t₂ 5=2.09, p<0.05). The improvement in performance for zolpidem condition occurred across the following day (test3-test2, t₂ 5=2.22, p<0.05), as no difference was observed between conditions after sleep (test2-test1, t₂ 5=0.34, p=0.74)
Conclusion
Consistent with previous studies, participants showed better memory performance after taking zolpidem compared to placebo. However, the current study showed that the improvement in memory occurred across a day of wakefulness after nighttime drug ingestion, while other studies observed improvements shortly after sleep, indicating a potential delayed benefit of zolpidem on memory consolidation.
Support
This work was supported by the Office of Naval Research grant N00014-14-1-0513
Journal Article
Optogenetic gamma stimulation rescues memory impairments in an Alzheimer’s disease mouse model
Slow gamma oscillations (30–60 Hz) correlate with retrieval of spatial memory. Altered slow gamma oscillations have been observed in Alzheimer’s disease. Here, we use the J20-APP AD mouse model that displays spatial memory loss as well as reduced slow gamma amplitude and phase-amplitude coupling to theta oscillations phase. To restore gamma oscillations in the hippocampus, we used optogenetics to activate medial septal parvalbumin neurons at different frequencies. We show that optogenetic stimulation of parvalbumin neurons at 40 Hz (but not 80 Hz) restores hippocampal slow gamma oscillations amplitude, and phase-amplitude coupling of the J20 AD mouse model. Restoration of slow gamma oscillations during retrieval rescued spatial memory in mice despite significant plaque deposition. These results support the role of slow gamma oscillations in memory and suggest that optogenetic stimulation of medial septal parvalbumin neurons at 40 Hz could provide a novel strategy for treating memory deficits in AD.
Slow gamma oscillations are associated with memory and have been reported to be disrupted in patients with Alzheimer’s disease. Here the authors show that optogenetic stimulation of medial septum parvalbumin neurons at 40 Hz rescues memory retrieval in the J20 mouse model of Alzheimer’s disease.
Journal Article
The hippocampal sharp wave–ripple in memory retrieval for immediate use and consolidation
Various cognitive functions have long been known to require the hippocampus. Recently, progress has been made in identifying the hippocampal neural activity patterns that implement these functions. One such pattern is the sharp wave–ripple (SWR), an event associated with highly synchronous neural firing in the hippocampus and modulation of neural activity in distributed brain regions. Hippocampal spiking during SWRs can represent past or potential future experience, and SWR-related interventions can alter subsequent memory performance. These findings and others suggest that SWRs support both memory consolidation and memory retrieval for processes such as decision-making. In addition, studies have identified distinct types of SWR based on representational content, behavioural state and physiological features. These various findings regarding SWRs suggest that different SWR types correspond to different cognitive functions, such as retrieval and consolidation. Here, we introduce another possibility — that a single SWR may support more than one cognitive function. Taking into account classic psychological theories and recent molecular results that suggest that retrieval and consolidation share mechanisms, we propose that the SWR mediates the retrieval of stored representations that can be utilized immediately by downstream circuits in decision-making, planning, recollection and/or imagination while simultaneously initiating memory consolidation processes.
Journal Article