Tests of pattern separation and pattern completion in humans—A systematic review

Liu, Kathy; Gould, Rebecca L.; Coulson, Mark; Ward, Emma V.; Howard, Robert

doi:10.1002/hipo.22561

Cited by 61 publications

(49 citation statements)

References 88 publications

(146 reference statements)

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“…It is notable that all of the aforementioned studies reported that SenseCam photographs led patients to recall event details that were not themselves apparent in the images. This suggests that these automatically captured first‐person snapshots might be particularly effective at triggering mnemonic pattern‐completion processes, perhaps by harnessing the functional contribution of any intact portions of the patients’ hippocampi to bring associated event details back to mind. Indeed, Loveday and Conway reported that their amnesic patient would occasionally experience a “Proustian moment”—a powerful flood of recollected details—when encountering her SenseCam photographs.…”

Section: Research In Clinical Contextsmentioning

confidence: 99%

Neurocognitive mechanisms of real‐world autobiographical memory retrieval: insights from studies using wearable camera technology

Chow¹,

Rissman

2017

Annals of the New York Academy of Sciences

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In recent years, investigation into the cognitive and neural mechanisms of autobiographical memory has been aided by the use of experimental paradigms incorporating wearable camera technology. By effortlessly capturing first-person images of one's life events, these cameras provide a rich set of naturalistic stimuli that can later be used to trigger the recall of specific episodes. Here, we chronicle the development and progression of such studies in behavioral and neuroimaging examinations of both clinical and nonclinical adult populations. Experiments examining the effects of periodic review of first-person images of life events have documented enhancements of autobiographical memory retrieval. Such benefits are most pronounced in patients with memory impairments, but there is mounting evidence that cognitively healthy individuals may benefit as well. Findings from functional magnetic resonance imaging experiments using wearable camera stimuli as retrieval probes have produced results that, although largely consistent with the broader episodic memory literature, have significantly extended prior findings concerning the underlying mnemonic processes and the neural representation of autobiographical information. Taken together, wearable camera technology provides a unique opportunity for studies of autobiographical memory to more closely approximate real-world conditions, thus offering enhanced ecological validity and opening up new avenues for experimental work.

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Section: Research In Clinical Contextsmentioning

confidence: 99%

Neurocognitive mechanisms of real‐world autobiographical memory retrieval: insights from studies using wearable camera technology

Chow¹,

Rissman

2017

Annals of the New York Academy of Sciences

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“…Notably, this deficit is apparent in tests of pattern separation unrelated to the particular trauma: humans diagnosed with PTSD or related anxiety disorders perform poorly on neuropsychological tests of pattern separation 22 . By contrast, some humans diagnosed with autism spectrum disorder have enhanced pattern separation and note even slight differences in contexts or routines 110 . In PTSD, the severity of symptoms is correlated with a smaller and less active DG, as compared to healthy controls.…”

Section: Pattern Separationmentioning

confidence: 99%

Re-evaluating the link between neuropsychiatric disorders and dysregulated adult neurogenesis

Yun

Reynolds

Masiulis

et al. 2016

Nat Med

113

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People diagnosed with neuropsychiatric disorders such as depression, anxiety, addiction or schizophrenia often have dysregulated memory, mood, pattern separation and/or reward processing. These symptoms are indicative of a disrupted function of the dentate gyrus (DG) subregion of the brain, and they improve with treatment and remission. The dysfunction of the DG is accompanied by structural maladaptations, including dysregulation of adult-generated neurons. An increasing number of studies using modern inducible approaches to manipulate new neurons show that the behavioral symptoms in animal models of neuropsychiatric disorders can be produced or exacerbated by the inhibition of DG neurogenesis. Thus, here we posit that the connection between neuropsychiatric disorders and dysregulated DG neurogenesis is beyond correlation or epiphenomenon, and that the regulation of adult-generated DG neurogenesis merits continued and focused attention in the ongoing effort to develop novel treatments for neuropsychiatric disorders.

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“…The hippocampus is necessary for recollection because of its unique ability to assign independent representations to even highly similar stimuli (Lacy, Yassa, Stark, Muftuler, & Stark, 2011; through processes known as pattern separation and pattern completion. Our experimental design was however not meant to test for pattern separation (see Liu, Gould, Coulson, Ward, & Howard, 2016) and the resolution of our fMRI data would not allow for correlational multi-voxel pattern analyses across subfields of the hippocampus, believed to have distinct contributions to pattern separation/completion (e.g. .…”

Section: Introductionmentioning

confidence: 99%

Sleep deprivation disrupts the contribution of the hippocampus to the formation of novel lexical associations

2017

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a b s t r a c tSleep is involved in the mechanisms underlying memory consolidation and brain plasticity. Consolidation refers to a process through which labile memories are reorganized into more stable ones. An intriguing but often neglected question concerns how pre-existing knowledge is modified when new information enters memory, and whether sleep can influence this process. We investigated how nonword learning may modify the neural representations of closely-related existing words. We also tested whether sleep contributes to any such effect by comparing a group of participants who slept during the night following a first encoding session to a sleep deprived group. Thirty participants were first intensively trained at writing nonwords on Day 1 (remote nonwords) and Day 4 (recent nonwords), following which they underwent functional MRI. This session consisted of a word lexical decision task including words orthographically-close to the trained nonwords, followed by an incidental memory task on the nonwords. Participants who slept detected real words related to remote nonwords faster than those related to recent nonwords, and showed better explicit memory for the remote nonwords. Although the full interaction comparing both groups for these effects was not significant, we found that participants from the sleep-deprivation group did not display such differences between remote and recent conditions. Imaging results revealed that the functional interplay between hippocampus and frontal regions critically mediated these behavioral effects. This study demonstrates that sleep may not only strengthen memory for recently learned items but also promotes a constant reorganization of existing networks of word representations, allowing facilitated access to orthographically-close words.

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Tests of pattern separation and pattern completion in humans—A systematic review

Cited by 61 publications

References 88 publications

Neurocognitive mechanisms of real‐world autobiographical memory retrieval: insights from studies using wearable camera technology

Neurocognitive mechanisms of real‐world autobiographical memory retrieval: insights from studies using wearable camera technology

Re-evaluating the link between neuropsychiatric disorders and dysregulated adult neurogenesis

Sleep deprivation disrupts the contribution of the hippocampus to the formation of novel lexical associations

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