Episodic memory in primates.

Episodic memory refers to a system of memory with the capacity to recollect specific events from an individual's life. Some psychologists have suggested that episodic memory is a uniquely human phenomenon. We challenge that idea and present evidence that great apes and other primates may possess episodic-like memory. We review criteria developed to assess episodic-like memory in nonhumans, and how they apply to primates. In particular, we discuss the criteria of Clayton et al. [2001], who stated that episodic-like memory is based on the retrieval of multiple and integrated components of an event. We then review eight studies examining memory in great apes and apply the Clayton et al. criteria to each of them. We summarize the evidence that is compatible with the existence of episodic-like memory, although none of the data completely satisfy the Clayton et al. criteria. Morover, feelings of pastness and feelings of confidence, which mark episodic memory in humans, have not been empirically addressed in nonhuman primates. Future studies should be directed at these aspects of memory in primates. We speculate on the functional significance of episodic memory in nonhuman primates.     

Prospective and retrospective duration memory in the hippocampus: is time in the foreground or background?

Psychologists have long distinguished between prospective and retrospective timing to highlight the difference between our sense of duration during an experience in passing and our sense of duration in hindsight. Humans and other animals use prospective timing in the seconds-to-minutes range in order to learn durations, and can organize their behaviour based upon this knowledge when they know that duration information will be important ahead of time. By contrast, when durations are estimated after the fact, thus precluding the subject from consciously attending to temporal information, duration information must be extracted from other memory representations. The accumulated evidence from prospective timing research has generally led to the hippocampus (HPC) being casted in a supporting role with prefrontal–striatal, cortical or cerebellar circuits playing the lead. Here, I review findings from the animal and human literature that have led to this conclusion and consider that the contribution of the HPC to duration memory is understated because we have little understanding about how we remember duration.     

Leisure Activity,Brain β‐amyloid,and Episodic Memory in Adults with Down Syndrome

The present study provided an investigation of associations between leisure activity and early Alzheimer’s disease neuropathology (i.e., brain β‐amyloid) and episodic memory in a sample of 65 adults with Down syndrome (aged 30–53 years), at baseline and follow‐up, approximately three years apart. Findings indicated that leisure activity at baseline was not associated with brain β‐amyloid at baseline or change in brain β‐amyloid from baseline to follow‐up. Greater cognitively stimulating leisure activity at baseline was associated with better episodic memory at baseline, and greater social leisure activity at baseline was associated with less decline in episodic memory from baseline to follow‐up. High (as opposed to low) levels of social and overall leisure activity at baseline moderated the association between increase in brain β‐amyloid and decline in episodic memory, from baseline to follow‐up. Findings suggest that cognitively stimulating and social leisure activity could protect against the effect of Alzheimer’s disease neuropathology on episodic memory in adults with Down syndrome.     

Redefining Single-Trial Memories in the Honeybee

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New Episodic Learning Interferes with the Reconsolidation of Autobiographical Memories

It is commonly assumed that, with time, an initially labile memory is transformed into a permanent one via a process of consolidation. Yet, recent evidence indicates that memories can return to a fragile state again when reactivated, requiring a period of reconsolidation. In the study described here, we found that participants who memorized a story immediately after they had recalled neutral and emotional experiences from their past were impaired in their memory for the neutral (but not for the emotional) experiences one week later. The effect of learning the story depended critically on the preceding reactivation of the autobiographical memories since learning without reactivation had no effect. These results suggest that new learning impedes the reconsolidation of neutral autobiographical memories.     

记忆水平依赖的海马-前额叶神经节律交互

海马(HPC)和前额叶皮层(PFC)的协同作用是记忆加工过程的关键,其相互作用对学习和记忆功能至关重要.大量证据表明,情景记忆的形成、巩固与检索依赖于特征神经节律在PFC和HPC脑区间的同步作用,这些节律包括theta节律、gamma节律和sharp wave ripples (SWRs)节律等.在精神类疾病中患者往往伴随出现学习记忆功能障碍,基于人类和动物的脑电研究均发现以上3种神经节律在HPC和PFC之间的同步性下降,可能作为反映精神病理下认知功能障碍的重要指标.本文从HPC-PFC网络中的神经节律研究出发,总结了theta节律、gamma节律和SWRs节律在两脑区间的协调交互模式在情景记忆中的作用,以及精神分裂症和抑郁症状态下HPC-PFC通路上神经节律的异常表现及其潜在损伤机制,为今后精神疾病的快速诊断提供客观依据.     

Rhythmic Pruning of Perceptual Noise for Object Representation in the Hippocampus and Perirhinal Cortex in Rats

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成年大鼠海马CA1区锥体神经元外向整流氯离子单通道特性

采用膜片钳内面向外式技术,在急性分离成年大鼠海马CAl区锥体细胞上记录到了外向整流氯离子通道（outwardly rectifying chloride channel,ORCC）.长时间去极化（≥60 mV）刺激后,在30%的游离膜片上记录到有外向整流特性的单通道氯电流,膜电位在－60 mV到0 mV之间的单通道电导为(16.58±1.54) pS（n=10）,而在0 mV到+60 mV之间电导为（40.92±3.17） pS.通道开放概率有明显的电压依赖性(膜电位－60 mV时,P_o=0.44±0.12;膜电位为+60 mV时,P_o=0.86±0.06, n=10).在对称Cl^－浓度（150 mmol/L）时,通道翻转电位为(－4.17±1.84) mV.当溶液中部分NaCl被葡萄糖酸钠替代后,翻转电位为：(－34.23±4.86) mV (［Cl^－］_i/［Cl^－］_o=(30 mmol/L)/(150 mmol/L)),接近氯离子通道的理论值,这表明通道具有氯离子选择性.浴槽液中分别加入氯通道阻断剂DIDS和SITS可以使+40 mV的通道开放概率从(0.83±0.06)和(0.86±0.06)分别降低到(0.12±0.05)和(0.13±0.04)（n=5）,冲洗后可使开放概率基本恢复.上述研究结果显示,在成年大鼠海马CA1神经元上存在外向整流氯离子通道.     

Observational learning promotes hippocampal remote awake replay toward future reward locations

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