The operation of pattern separation and pattern completion processes associated with different attributes or domains of memory

Hunsaker, Michael R.; Kesner, Raymond P.

doi:10.1016/j.neubiorev.2012.09.014

Cited by 246 publications

(291 citation statements)

References 209 publications

Supporting

Mentioning

269

Contrasting

Order By: Relevance

“…The lower spatial resolution here compared to previous fMRI studies of hippocampal pattern separation (Bakker et al, 2008; is the most likely explanation, as the current data did not permit anatomical separation of responses in the hippocampal subregions in which pattern separation (DG) and completion (CA1) signals have previously been reported (e.g., Hunsaker and Kesner, 2013;Leutgeb et al, 2007).…”

Section: Pattern Separation and Pattern Completioncontrasting

confidence: 58%

“…Because of the nature of the BOLD signal, the parametric fMRI analyses can provide only relatively indirect measures of pattern separation and completion compared to direct neuronal recordings (Hunsaker and Kesner, 2013). Converging evidence of these processes in human studies could also be provided by representational similarity analysis (Kriegeskorte et al, 2008).…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

“…Conversely, overlapping input is used at retrieval as a cue to drive reinstatement of existing traces via pattern completion, increasing overlap between incoming and existing representations (Marr, 1971;McNaughton and Morris, 1987;O'Reilly and McClelland, 1994). Although pattern separation is by definition an encoding process, and pattern completion a retrieval process, either or both can be elicited by a single event, whether novel or previously encountered (Hunsaker and Kesner, 2013). Efficient pattern separation at encoding is thought to contribute to later mnemonic discrimination between events with similar representations, while false recognition of similar events can result from inefficient pattern separation or dominance of pattern completion at encoding (Sahay et al, 2011;Stark et al, 2013;Wilson et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, examination of neural responses to graded change in input, i.e., to stimuli of varying similarity relative to previously presented items, can provide further support for their presence (Hunsaker and Kesner, 2013;Kumaran and Maguire, 2009). Pattern separation is defined as reduction in overlap of output representations from a region relative to the degree of overlap of input representations received by the region (Rolls, 1996;Treves and Rolls, 1992).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cortical pattern separation and item-specific memory encoding

Pidgeon

Morcom

2016

Neuropsychologia

View full text Add to dashboard Cite

Pattern separation and pattern completion are fundamental brain processes thought to be critical for episodic memory encoding and retrieval, and for discrimination between similar memories. These processes are best understood in the hippocampus, but are proposed to occur throughout the brain, in particular in sensory regions. Cortical, as well as hippocampal, pattern separation may therefore support formation of event-unique memory traces. Using fMRI, we investigated cortical pattern separation and pattern completion and their relationship to encoding activity predicting subsequent item-specific compared to gist memory. During scanning, participants viewed images of novel objects, repeated objects, and objects which were both perceptually and conceptually similar to previously presented images, while performing a size judgement task. In a later surprise recognition test, they judged whether test items were 'same' 'similar' or 'new' relative to studied items. Activity consistent with pattern separation -responses to similar items as if novel -was observed in bilateral occipito-temporal cortex. Activity consistent with pattern completion -responses to similar items as if repeated -was observed in left prefrontal cortex and hippocampus. Curve fitting analysis further revealed that graded responses to change in image conceptual and perceptual similarity in bilateral prefrontal and right parietal regions met specific computational predictions for pattern separation for one or both of these similarity dimensions. Functional overlap between encoding activity predicting subsequent item-specific recognition and pattern separation activity was also observed in left occipital cortex and bilateral inferior frontal cortex. The findings suggest that extrahippocampal regions including sensory and prefrontal cortex contribute to pattern separation and pattern completion of visual input, consistent with the proposal that cortical pattern separation contributes to formation of item-specific memory traces, facilitating accurate recognition memory.

show abstract

Section: Pattern Separation and Pattern Completioncontrasting

confidence: 58%

Section: Limitations and Future Directionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cortical pattern separation and item-specific memory encoding

Pidgeon

Morcom

2016

Neuropsychologia

View full text Add to dashboard Cite

show abstract

“…Evidence has converged from many sources, behavioural, anatomical, and neurophysiological and from computational modelling, that the hippocampus supports distinct encoding and retrieval via the processes of pattern separation and pattern completion (Hunsaker & Kesner, 2013). Pattern completion is the retrieval of a memory for an item based on a degraded or partial stimulus cue (Hunsaker & Kesner, 2013).…”

Section: Time Manages Interference 3 Time Manages Interference In Vismentioning

confidence: 99%

Time manages interference in visual short-term memory

Smith

McKeown

Bunce

2017

Memory

View full text Add to dashboard Cite

Emerging evidence suggests that age-related declines in memory may reflect a failure in pattern separation, a process that is believed to reduce the encoding overlap between similar stimulus representations during memory encoding. Indeed, behavioural pattern separation may be indexed by a visual continuous recognition task in which items are presented in sequence and observers report for each whether it is novel, previously viewed (old), or whether it shares features with a previously viewed item (similar). In comparison to young adults, older adults show a decreased pattern separation when the number of items between 'old' and 'similar' items is increased. Yet the mechanisms of forgetting underpinning this type of recognition task are yet to be explored in a cognitively homogenous group, with careful control over the parameters of the task, including elapsing time (a critical variable in models of forgetting). By extending the inter-item intervals, number of intervening items, and overall decay interval, we observed in a young adult sample (N=35, Mage=19.56years) that the critical factor governing performance was inter-item interval. We argue that tasks using behavioural continuous recognition to index pattern separation in immediate memory will benefit from generous inter-item spacing, offering protection from inter-item interference.

show abstract

Pattern separation and pattern completion in Alzheimer's disease: Evidence of rapid forgetting in amnestic mild cognitive impairment

et al. 2013

View full text Add to dashboard Cite

Over the past four decades, the characterization of memory loss associated with Alzheimer's disease (AD) has been extensively debated. Recent iterations have focused on disordered encoding versus rapid forgetting. To address this issue, we used a behavioral pattern separation task to assess the ability of the hippocampus to create and maintain distinct and orthogonalized visual memory representations in patients with amnestic mild cognitive impairment (aMCI) and mild AD. We specifically used a lag-based continuous recognition paradigm to determine whether patients with aMCI and mild AD fail to encode visual memory representations or whether these patients properly encode representations that are rapidly forgotten. Consistent with the rapid forgetting hypothesis of AD, we found that patients with aMCI demonstrated decreasing pattern separation rates as the lag of interfering objects increased. In contrast, patients with AD demonstrated consistently poor pattern separation rates across three increasingly longer lags. We propose a continuum that reflects underlying hippocampal neuropathology whereby patients with aMCI are able to properly encode information into memory but rapidly lose these memory representations, and patients with AD, who have extensive hippocampal and parahippocampal damage, cannot properly encode information in distinct, orthogonal representations. Our results also revealed that whereas patients with aMCI demonstrated similar behavioral pattern completion rates to healthy older adults, patients with AD showed lower pattern completion rates when we corrected for response bias. Finally, these behavioral pattern separation and pattern completion results are discussed in terms of the dual process model of recognition memory.

show abstract

The operation of pattern separation and pattern completion processes associated with different attributes or domains of memory

Cited by 246 publications

References 209 publications

Cortical pattern separation and item-specific memory encoding

Cortical pattern separation and item-specific memory encoding

Time manages interference in visual short-term memory

Pattern separation and pattern completion in Alzheimer's disease: Evidence of rapid forgetting in amnestic mild cognitive impairment

Contact Info

Product

Resources

About