Tests of pattern separation and pattern completion in humans - a systematic review

OBJECTIVE: To systematically review the characteristics, validity and outcome measures of tasks that have been described in the literature as assessing pattern separation and pattern completion in humans. METHODS: Electronic databases were searched for articles. Parameters for task validity were obtained from two reviews that described optimal task design factors to evaluate pattern separation and pattern completion processes. These were that pattern separation should be tested during an encoding task using abstract, never-before-seen visual stimuli, and pattern completion during a retrieval task using partial cues; parametric alteration of the degree of interference of stimuli or degradation of cues should be used to generate a corresponding gradient in behavioral output; studies should explicitly identify the specific memory domain under investigation (sensory/perceptual, temporal, spatial, affect, response, or language) and account for the contribution of other potential attributes involved in performance of the task. A systematic, qualitative assessment of validity in relation to these parameters was performed, along with a review of general validity and task outcome measures. RESULTS: Sixty-two studies were included. The majority of studies investigated pattern separation and most tasks were performed on young, healthy adults. Pattern separation and pattern completion were most frequently tested during a retrieval task using familiar or recognizable visual stimuli and cues. Not all studies parametrically altered the degree of stimulus interference or cue degradation, or controlled for potential confounding factors. CONCLUSION: This review found evidence that some of the parameters for task validity have been followed in some human studies of pattern separation and pattern completion, but no study was judged to have adequately met all the parameters for task validity. The contribution of these parameters and other task design factors towards an optimal behavioral paradigm is discussed and recommendations for future research are made. This article is protected by copyright. All rights reserved

Tests of pattern separation and pattern completion in humans - a systematic review

OBJECTIVE: To systematically review the characteristics, validity and outcome measures of tasks that have been described in the literature as assessing pattern separation and pattern completion in humans. METHODS: Electronic databases were searched for articles. Parameters for task validity were obtained from two reviews that described optimal task design factors to evaluate pattern separation and pattern completion processes. These were that pattern separation should be tested during an encoding task using abstract, never-before-seen visual stimuli, and pattern completion during a retrieval task using partial cues; parametric alteration of the degree of interference of stimuli or degradation of cues should be used to generate a corresponding gradient in behavioral output; studies should explicitly identify the specific memory domain under investigation (sensory/perceptual, temporal, spatial, affect, response, or language) and account for the contribution of other potential attributes involved in performance of the task. A systematic, qualitative assessment of validity in relation to these parameters was performed, along with a review of general validity and task outcome measures. RESULTS: Sixty-two studies were included. The majority of studies investigated pattern separation and most tasks were performed on young, healthy adults. Pattern separation and pattern completion were most frequently tested during a retrieval task using familiar or recognizable visual stimuli and cues. Not all studies parametrically altered the degree of stimulus interference or cue degradation, or controlled for potential confounding factors. CONCLUSION: This review found evidence that some of the parameters for task validity have been followed in some human studies of pattern separation and pattern completion, but no study was judged to have adequately met all the parameters for task validity. The contribution of these parameters and other task design factors towards an optimal behavioral paradigm is discussed and recommendations for future research are made. This article is protected by copyright. All rights reserved

Age-related Neural Correlates of Multifeatural Encoding

Past research has demonstrated age-related structural and functional changes that contribute to declines in episodic memory performance. More specifically, there have been age-related functional connectivity changes to key regions including the medial temporal lobes and prefrontal cortex, as well as within the default mode network. Prior studies investigating age-related episodic encoding have either performed activation analyses, or have performed functional connectivity analyses but only regarding memory of a single association or single feature. Hence, age-related connectivity changes for memory of multiple features remain widely unstudied. Using a fMRI multidimensional source memory paradigm, this study sought to further understand the effect of aging on intra-item multifeatural encoding connectivity. Overall, results supported the hypothesis that young adults would display significantly more functional connectivity relative to older adults to the frontal and parietal lobes for multifeatural trials. A majority of these regions were also corroborated by a similar multifeatural inter-item encoding study by James et al. (2019). However, this study was limited by a small sample size and decreased statistical power. Future studies should seek to address these limitations, investigate reconnectivity at retrieval, and attempt to better differentiate between connectivity unique to multifeatural inter-item versus intra-item encoding. Keywords: episodic memory, encoding, functional connectivity, agingBachelor of Art

The two-component model of memory development, and its potential implications for educational settings

We recently introduced a two-component model of the mechanisms underlying age differences in memory functioning across the lifespan. According to this model, memory performance is based on associative and strategic components. The associative component is relatively mature by middle childhood, whereas the strategic component shows a maturational lag and continues to develop until young adulthood. Focusing on work from our own lab, we review studies from the domains of episodic and working memory informed by this model, and discuss their potential implications for educational settings. The episodic memory studies uncover the latent potential of the associative component in childhood by documenting children's ability to greatly improve their memory performance following mnemonic instruction and training. The studies on working memory also point to an immature strategic component in children whose operation is enhanced under supportive conditions. Educational settings may aim at fostering the interplay between associative and strategic components. We explore possible routes towards this goal by linking our findings to recent trends in research on instructional design

TheRelationship between brain network organization and variability in episodic memory outcomes and abilities:

Thesis advisor: Maureen RitcheyThesis advisor: Elizabeth KensingerOur brains afford us the remarkable ability to remember past events from our lives, to travel back in time in our minds' eye and relive our memories anew. What are the brain processes that support this ability? In this thesis I investigated this question across three experiments. In Chapter 1, I examined how the brain regions previously linked to episodic cognition (i.e., the hippocampus, parahippocampal cortex, retrosplenial cortex, posterior cingulate cortex, precuneus, angular gyrus, and medial prefrontal cortex) support recollection by building a model that incorporates both region-specific and network-level contributions. I found that these brain regions form ventral and dorsal subnetworks and that their contributions to recollection outcomes are largely explained by subnetwork-level rather than region-specific engagement. In Chapter 2, I used an openly available MRI dataset to test whether individual differences in functional connectivity were related to individual differences in memory ability, finding that network connectivity outside of the classic episodic networks supports individual differences in our ability to remember. In Chapter 3, I tested a neuroscience inspired hypothesis that individuals would have different capacities to bind their memories around social-emotional and visual-spatial content, ultimately finding inconclusive evidence for or against my hypothesis. Together, these results help to solidify our understanding of the brain as an interconnected network of brain regions and shed new light on how these networks support individual differences in memory.Thesis (PhD) — Boston College, 2023.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Psychology

Out of Place, Out of Mind: Schema-Driven False Memory Effects for Object-Location Bindings

Events consist of diverse elements, each processed in specialized neocortical networks, with temporal lobe memory systems binding these elements to form coherent event memories. We provide a novel theoretical analysis of an unexplored consequence of the independence of memory systems for elements and their bindings, 1 that raises the paradoxical prediction that schema-driven false memories can act solely on the binding of event elements despite the superior retrieval of individual elements. This is because if 2, or more, schema-relevant elements are bound together in unexpected conjunctions, the unexpected conjunction will increase attention during encoding to both the elements and their bindings, but only the bindings will receive competition with evoked schema-expected bindings. We test our model by examining memory for object-location bindings in recognition (Study 1) and recall (Studies 2 and 3) tasks. After studying schema-relevant objects in unexpected locations (e.g., pan on a stool in a kitchen scene), participants who then viewed these objects in expected locations (e.g., pan on stove) at test were more likely to falsely remember this object-location pairing as correct, compared with participants that viewed a different unexpected object-location pairing (e.g., pan on floor). In recall, participants were more likely to correctly remember individual schema-relevant objects originally viewed in unexpected, as opposed to expected locations, but were then more likely to misplace these items in the original room scene to expected places, relative to control schema-irrelevant objects. Our theoretical analysis and novel paradigm provide a tool for investigating memory distortions acting on binding processes

The role of phonology in visual word recognition: evidence from Chinese

Posters - Letter/Word Processing V: abstract no. 5024The hypothesis of bidirectional coupling of orthography and phonology predicts that phonology plays a role in visual word recognition, as observed in the effects of feedforward and feedback spelling to sound consistency on lexical decision. However, because orthography and phonology are closely related in alphabetic languages (homophones in alphabetic languages are usually orthographically similar), it is difficult to exclude an influence of orthography on phonological effects in visual word recognition. Chinese languages contain many written homophones that are orthographically dissimilar, allowing a test of the claim that phonological effects can be independent of orthographic similarity. We report a study of visual word recognition in Chinese based on a mega-analysis of lexical decision performance with 500 characters. The results from multiple regression analyses, after controlling for orthographic frequency, stroke number, and radical frequency, showed main effects of feedforward and feedback consistency, as well as interactions between these variables and phonological frequency and number of homophones. Implications of these results for resonance models of visual word recognition are discussed.postprin