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Abstract: Episodic memory provides information about the “when” of events as well as “what” and “where” they happened. Using functional imaging, we investigated the domain specificity of retrieval-related processes following encoding of complex, naturalistic events. Subjects watched a 42-min TV episode, and 24h later, made discriminative choices of scenes from the clip during fMRI. Subjects were presented with two scenes and required to either choose the scene that happened earlier in the film (Temporal), or the scene with a correct spatial arrangement (Spatial), or the scene that had been shown (Object). We identified a retrieval network comprising the precuneus, lateral and dorsal parietal cortex, middle frontal and medial temporal areas. The precuneus and angular gyrus are associated with temporal retrieval, with precuneal activity correlating negatively with temporal distance between two happenings at encoding. A dorsal fronto-parietal network engages during spatial retrieval, while antero-medial temporal regions activate during object-related retrieval. We propose that access to episodic memory traces involves different processes depending on task requirements. These include memory-searching within an organised knowledge structure in the precuneus (Temporal task), online maintenance of spatial information in dorsal fronto-parietal cortices (Spatial task) and combining scene-related spatial and non-spatial information in the hippocampus (Object task). Our findings support the proposal of process-specific dissociations of retrieval. [Copyright &y& Elsevier]

Abstract: Previous studies with macaque monkeys have found rapid learning to be impaired in both spatial (visuospatial) and non-spatial (visuomotor) associative learning tasks after fornix transection. In order to test theories that posit a general role for the fornix in associative learning, we investigated whether monkeys with fornix transection would also be impaired in the rapid acquisition of visuovisual conditional associations. We trained monkeys, postoperatively, on three sets of conditional stimulus–stimulus concurrent associations. Fornix transection did not impair learning of these associations, even in the early stages; to the contrary, animals with fornix transection made significantly fewer perseverative errors during the initial acquisition stages. These results challenge the idea that the hippocampal system plays a general role in the rapid acquisition of all kinds of associative knowledge. We suggest that the lower error rate in the early stages of the non-spatial task in the fornix transected animals may be secondary to an impairment in visuospatial processing; this might act to bias animals away from attempts to learn about spatial strategies for solving novel tasks. Additionally, we observed that fornix transected and control monkeys adopted a Change-shift response strategy in this task; the use of which was found to be fornix independent. [Copyright &y& Elsevier]

Schizophrenia is associated with memory disorders that affect patients in their daily life. Patients complain about difficulty to remember knowledge that has been recently learnt together with its context (episodic memory, EM) but also more complex events that have been personally experienced (autobiographical memory, AM). While deficits at both encoding and retrieval have been shown to account for EM disorders in schizophrenia, the cognitive mechanisms involved in AM disorders are more difficult to approach. This is partly explained by the conceptual difference between EM and AM. Some methodological limitations inherent to the AM research also reduce the possibility to investigate the early processing of complex and dynamic real-life events at encoding; rather the retrieval processes engaged have therefore been the focus of the bulk of extant research. The aim of this review is to summarize the main findings related to EM and AM research in patients with schizophrenia, to discuss the putative mechanisms that may account for patients' AM impairment, based in particular on the literature about EM, and to provide an agenda for future research aiming to further elucidate the role of encoding deficits in AM in patients. • Episodic memory and autobiographical memory (AM) are altered in schizophrenia. • AM in schizophrenia is under-studied due to methodological limitations. • Naturalistic stimuli and wearable cameras can aid studying AM encoding. • Future works must bridge the gap between episodic and AM research. [ABSTRACT FROM AUTHOR]

Metacognition as the capacity of monitoring one's own cognition operates across domains. Here, we addressed whether metacognition in different cognitive domains rely on common or distinct neural substrates with combined diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) techniques. After acquiring DTI and resting-state fMRI data, we asked participants to perform a temporal-order memory task and a perceptual discrimination task, followed by trial-specific confidence judgments. DTI analysis revealed that the structural integrity (indexed by fractional anisotropy) in the anterior portion of right superior longitudinal fasciculus (SLF) was associated with both perceptual and mnemonic metacognitive abilities. Using perturbed mnemonic metacognitive scores produced by inhibiting the precuneus using TMS, the mnemonic metacognition scores did not correlate with individuals' SLF structural integrity anymore, revealing the relevance of this tract in memory metacognition. To further verify the involvement of several cortical regions connected by SLF, we took the TMS-targeted precuneus region as a seed in a functional connectivity analysis and found the functional connectivity between precuneus and two SLF-connected regions (inferior parietal cortex and precentral gyrus) mediated mnemonic metacognition performance. These results illustrate the importance of SLF and a putative white-matter grey-matter circuitry that supports human metacognition. • Superior longitudinal fasciculus (SLF) integrity associated with metacognition. • Metamemory and SLF integrity correlation reduced by transient precuneus lesion. • Metamemory increases with precuneal-frontal-IPL functional connectivity. [ABSTRACT FROM AUTHOR]

Whether nonhuman primate species can construct, still less reconstruct, order of past events remains controversial. Here we show that rhesus macaques are capable of reconstructing the temporal order of memory traces of dynamic videos. We made use of 2000 unseen naturalistic videos of wildlife content for encoding, and then probed monkeys' recollection of temporal-order of events with a temporal-order judgement (TOJ) test. This encoding-TOJ procedure was repeated at three different time points (day 1, day 2, and day 32+). We specifically tested for differential TOJ memory performance for videos that were displayed in a reverse sequence versus videos that were displayed in a normal sequence at these different time points. We observed that during TOJ monkeys committed more errors for video content that were shown in reverse but only upon re-exposures (i.e., day 2 and day 32+). Moreover, this memory distortion effect is significantly accentuated by social relevance of the video content. We interpret that the monkeys reversed the out-of-order events in accordance to their knowledge priors; such fallaciously re-ordered memory traces then led to higher rate of errors. Demonstrating in macaque monkeys a form of errors in temporal-order memory for reverse videos carries implications for studying memory retrospection in the primates. [ABSTRACT FROM AUTHOR]