Cortical Representations of Visual Stimuli Shift Locations with Changes in Memory States

Long, Nicole M.; Kuhl, Brice A.

doi:10.1016/j.cub.2021.01.004

Cited by 31 publications

(36 citation statements)

References 71 publications

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“…One intriguing possibility is that these representations are prioritized according to biased competition ( Desimone, 1998 ; Hutchinson et al, 2016 ), leading to preferential routing and subsequent encoding of predicted, but not perceived, information in the hippocampus. Relatedly, recent work had found that encoding vs. retrieval states are associated with distinct patterns of activity in visual cortex ( Long and Kuhl, 2021 ), suggesting that representations in visual regions may be fundamentally shaped by memory state in the hippocampus.…”

Section: Discussionmentioning

confidence: 99%

Temporal dynamics of competition between statistical learning and episodic memory in intracranial recordings of human visual cortex

Sherman

Graves

Huberdeau

et al. 2022

Preprint

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The function of long-term memory is not just to reminisce about the past, but also to make predictions that help us behave appropriately and efficiently in the future. This predictive function of memory provides a new perspective on the classic question from memory research of why we remember some things but not others. If prediction is a key outcome of memory, then the extent to which an item generates a prediction signifies that this information already exists in memory and need not be encoded. We tested this principle using human intracranial EEG as a time-resolved method to quantify prediction in visual cortex during a statistical learning task and link the strength of these predictions to subsequent episodic memory behavior. Epilepsy patients viewed rapid streams of scenes, some of which contained regularities that allowed the category of the next scene to be predicted. We verified that statistical learning occurred using neural frequency tagging and measured category prediction with multivariate pattern analysis. Although neural prediction was robust overall, this was driven entirely by items that were subsequently forgotten. Such interference provides a mechanism by which prediction can regulate memory formation to prioritize encoding of information that could help learn new predictive relationships.

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Section: Discussionmentioning

confidence: 99%

Temporal dynamics of competition between statistical learning and episodic memory in intracranial recordings of human visual cortex

Sherman

Graves

Huberdeau

et al. 2022

Preprint

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“…As discussed earlier, a wider network of regions beyond the hippocampus have been implicated in memoryguided predictions and contextual reactivations (Bar and Aminoff, 2003;Lee and Kuhl, 2016;Livne and Bar, 2016;Jonker et al, 2018;Caplette et al, 2020;Long and Kuhl, 2021). The PM network is functionally connected to the posterior hippocampus, and associated with reactivation of contextuallyrelevant object information, whilst the AT network is connected to the anterior hippocampus and is thought to represent item information (Ranganath and Ritchey, 2012).…”

Section: Item and Expectation Effects In The Posterior Medial Cortexmentioning

confidence: 96%

Contextual Expectations Shape Cortical Reinstatement of Sensory Representations

2022

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When making a turn at a familiar intersection, we know what items and landmarks will come into view. These perceptual expectations, or predictions, come from our knowledge of the context, however it's unclear how memory and perceptual systems interact to support the prediction and reactivation of sensory details in cortex. To address this, human participants learned the spatial layout of animals positioned in a cross maze. During fMRI, participants of both sexes navigated between animals to reach a target, and in the process saw a predictable sequence of five animal images. Critically, to isolate activity patterns related to item predictions, rather than bottom-up inputs, one quarter of trials ended early, with a blank screen presented instead. Using multivariate pattern similarity analysis, we reveal that activity patterns in early visual cortex, posterior medial regions, and the posterior hippocampus showed greater similarity when seeing the same item compared to different items. Further, item effects in posterior hippocampus were specific to the sequence context. Critically, activity patterns associated with seeing an item in visual cortex and posterior medial cortex, were also related to activity patterns when an item was expected, but omitted, suggesting sequence predictions were reinstated in these regions. Finally, multivariate connectivity showed that patterns in the posterior hippocampus at one position in the sequence were related to patterns in early visual cortex and posterior medial cortex at a later position. Together, our results support the idea that hippocampal representations facilitate sensory processing by modulating visual cortical activity in anticipation of expected items. Significance statementOur visual world is a series of connected events, where we can predict what we might see next based on our recent past. Understanding the neural circuitry and mechanisms of the perceptual and memory systems that support these expectations is fundamental to revealing how we perceive and act in our world. Using brain imaging, we studied what happens when we expect to see specific visual items, and how such expectations relate to top-down memory signals. We find both visual and memory systems reflect item predictions, and moreover, we show that hippocampal activity supports predictions of future expected items. This demonstrates that the hippocampus acts to predict upcoming items, and reinstates such predictions in cortex.

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“…We further identified differences in the pattern of activation between first encoding and recognition. Differences between encoding and retrieval have been previously observed in mean activity (Cabeza & Nyberg, 2000;Daselaar et al, 2009), functional connectivity (Huijbers et al, 2011;Simons & Spiers, 2003), and object representations (Long & Kuhl, 2021). These discrepancies may reflect differences in the utility of the tasks (Simons & Spiers, 2003) or in differences in orienting attention between the memory stages (Chun & Turk-Browne, 2007;Wagner et al, 2005), which may be represented in neural activity leading to differential manifestations of neural dedifferentiation.…”

Section: Discussionmentioning

confidence: 94%

“Age-related declines in neural selectivity manifest differentially during encoding and recognition”

Pauley

Sommer²,

Kobelt³

et al. 2021

Preprint

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One important factor contributing to age-related memory decline is the loss of distinctiveness with which information is represented in brain activity. This loss in neural selectivity may be driven by neural attenuation (i.e., reduced activation to target stimuli) or neural broadening (i.e., increased activation to non-target stimuli). In this fMRI study, we assessed age differences in neural selectivity during first encoding, repeated encoding, and recognition, as well as the underlying pattern (broadening versus attenuation). We found lower neural selectivity in older compared to younger adults during all memory stages. Crucially, while reduced selectivity in older adults was due to neural broadening during first encoding, it was driven by neural attenuation during recognition, but revealed no clear pattern during repeated encoding. Our findings suggest that intrinsic differences between memory stages may interact with neural activity to manifest as either neural broadening or attenuation. Moreover, despite these differential patterns, neural selectivity was highly correlated across memory stages, indicating that one common mechanism may underly distinct expressions of age-related neural dedifferentiation.

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Cortical Representations of Visual Stimuli Shift Locations with Changes in Memory States

Cited by 31 publications

References 71 publications

Temporal dynamics of competition between statistical learning and episodic memory in intracranial recordings of human visual cortex

Temporal dynamics of competition between statistical learning and episodic memory in intracranial recordings of human visual cortex

Contextual Expectations Shape Cortical Reinstatement of Sensory Representations

“Age-related declines in neural selectivity manifest differentially during encoding and recognition”

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