TY - JOUR AB - The consolidation of long-term memory is thought to critically rely on sleep. However, first evidence from a study in Drosophila suggests that hunger, as another brain state, can benefit memory consolidation as well. Here, we report two human (within-subjects crossover) experiments examining the effects of fasting (versus satiated conditions) during a 10-hour post-encoding consolidation period on subsequent recall of declarative and procedural memories in healthy men. In Experiment 1, participants (n = 16), after an 18.5-hour fasting period, encoded 3 memory tasks (word paired associates, a visual version of the Deese-Roediger-McDermott task, finger tapping) and subsequently either continued to fast or received standardized meals. Recall was tested 48 h later in a satiated state. Experiment 2 (n = 16 participants) differed from Experiment 1 in that a What-Where-When episodic memory task replaced the Deese-Roediger-McDermott task and recall was tested only 24 h later in a fasted state. Compared with the satiated state, fasting enhanced cued recall of word paired associates (more correct and faster responses) and item recognition in the What-Where-When task. By contrast, fasting impaired recall of episodic context memory, i.e., spatial context in the Deese-Roediger-McDermott task, and temporal-spatial context in the What-Where-When task. Procedural memory (finger tapping) remained unaffected. The pattern suggests a differential effect of fasting selectively promoting consolidation of semantic-like representations in cortical networks whereas hippocampal representations of episodic context are weakened. We speculate that hunger strengthens cortical representations by suppressing hippocampal interference during wake consolidation. Yet, the underlying mechanism remains to be clarified. AU - Yang, X.* AU - Miao, X.* AU - Schweiggart, F.* AU - Großmann, S.* AU - Rauss, K.* AU - Hallschmid, M. AU - Born, J. AU - Lutz, N.D.* C1 - 73385 C2 - 57034 CY - 525 B St, Ste 1900, San Diego, Ca 92101-4495 Usa TI - The effect of fasting on human memory consolidation. JO - Neurobiol. Learn. Mem. VL - 218 PB - Academic Press Inc Elsevier Science PY - 2025 SN - 1074-7427 ER - TY - JOUR AB - Ample evidence has indicated a beneficial role of sleep, and particularly of slow wave sleep (SWS) in memory consolidation. However, how basic features of sleep, its depth and duration, contribute to this process remained elusive. Here, we investigated spatial object-place recognition (OPR) memory in rats, to systematically dissociate effects of sleep depth and duration on the formation of recent and remote hippocampus-dependent memory. Encoding of the spatial configuration was followed by an experimental post-encoding period of either 2 or 4 h, during which the rats had either "regular sleep", "deeper sleep", or were kept awake. A deeper sleep was achieved by an extended habituation of the rats to the sleep environment. Retrieval was tested either immediately after the 2-hour post-encoding period (recent memory test) or 1 week later (remote memory test). Deeper sleep expressed itself in a selective increase in the time spent in SWS, and in numbers of slow oscillations, spindles, and hippocampal ripples during SWS, whereas preREM and REM sleep were not affected. At the recent test, OPR memory was preserved only after sleep, but independent of its depth. At the remote test, however, OPR memory was preserved only after deeper sleep, whereas the wake and the regularly sleeping rats did not show remote OPR memory, even with the longer 4-h post-encoding period. Our results indicate that, rather than a longer duration, deeper sleep, i.e., a longer time in SWS together with enhanced oscillatory signatures of mnemonic processing during this sleep stage, occurring within a 2-hour window after encoding, is the factor that makes hippocampus-dependent memory more persistent. AU - Sawangjit, A.* AU - Oyanedel, C.N.* AU - Niethard, N.* AU - Born, J. AU - Inostroza, M.* C1 - 59253 C2 - 48741 CY - 525 B St, Ste 1900, San Diego, Ca 92101-4495 Usa TI - Deepened sleep makes hippocampal spatial memory more persistent. JO - Neurobiol. Learn. Mem. VL - 173 PB - Academic Press Inc Elsevier Science PY - 2020 SN - 1074-7427 ER - TY - JOUR AB - The processes that organize different thoughts and memories, allowing the separation of currently relevant and irrelevant information, are collectively known as cognitive control. The neuronal mechanisms of these processes can be investigated by place cell ensemble recordings during behaviors and environmental manipulations that present cognitive control challenges to selectively represent one of multiple possible alternative estimates of location. We review place cell studies that investigate responses to manipulations that dissociate the environment into two or more spatial frames of locations, often times to test notions of pattern separation. Manipulations, such as continuously rotating the recording chamber reveal that the ensemble discharge in hippocampus self-organizes into multiple, transiently-organized representations of space, each defined by the subset of coactive cells. Ensemble discharge in the hippocampus alternates between separate representations of frame-specific positions on timescales from 25 ms to several seconds. The dynamic, functional grouping of discharge into transiently co-active subsets of cells is predicted by the animal's changing behavioral needs. In addition to identifying neural correlates of cognitive control in hippocampus, these observations demonstrate that the separation of neuronal activity into distinctive representations depends on ongoing cognitive demands and that what can appear as noise, deviations from receptive field tuning, can substantially be the result of these internal knowledge-guided fluctuations. These findings inspire a new perspective that should be taken into account when investigating pattern separation - a perspective that emphasizes changes in hippocampal neural discharge that are happening on a short timescale and does not assume that patterns of neural discharge are steady and stationary across the several minutes of the recordings. AU - Kelemen, E. AU - Fenton, A.A.* C1 - 47662 C2 - 39717 CY - San Diego SP - 50-59 TI - Coordinating different representations in the hippocampus. JO - Neurobiol. Learn. Mem. VL - 129 PB - Academic Press Inc Elsevier Science PY - 2016 SN - 1074-7427 ER - TY - JOUR AB - Cortisol's effects on memory follow an inverted U-shaped function such that memory retrieval is impaired with very low concentrations, presumably due to insufficient activation of high-affine mineralocorticoid receptors (MR), or with very high concentrations, due to predominant low-affine glucocorticoid receptor (GR) activation. Through corresponding changes in re-encoding, the retrieval effect of cortisol might translate into a persistent change of the retrieved memory. We tested whether partial suppression of morning cortisol synthesis by metyrapone, leading to intermediate, circadian nadir-like levels with presumed predominant MR activation, improves retrieval, particularly of emotional memory, and persistently changes the memory. In a randomized, placebo-controlled, double-blind, within-subject cross-over design, 18 men were orally administered metyrapone (1g) vs. placebo at 4:00 AM to suppress the morning cortisol rise. Retrieval of emotional and neutral texts and pictures (learned 3 days earlier) was assessed 4 hours after substance administration, and a second time one week later. Metyrapone suppressed endogenous cortisol release to circadian nadir-equivalent levels at the time of retrieval testing. Contrary to our expectations, metyrapone significantly impaired free recall of emotional texts (p < .05), whereas retrieval of neutral texts or pictures remained unaffected. One week later, participants still showed lower memory for emotional texts in the metyrapone than placebo condition (p < .05). Our finding, that suppressing morning cortisol to nadir-like concentrations not only impairs acute retrieval, but also persistently weakens emotional memories corroborate the concept that retrieval effects of cortisol produce persistent memory changes, possibly by affecting re-encoding. AU - Rimmele, U.* AU - Besedovsky, L.* AU - Lange, T.* AU - Born, J. C1 - 43300 C2 - 36569 CY - San Diego SP - 102-107 TI - Emotional memory can be persistently weakened by suppressing cortisol during retrieval. JO - Neurobiol. Learn. Mem. VL - 119 PB - Academic Press Inc Elsevier Science PY - 2015 SN - 1074-7427 ER -