1
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Schmidig FJ, Ruch S, Henke K. Episodic long-term memory formation during slow-wave sleep. eLife 2024; 12:RP89601. [PMID: 38661727 PMCID: PMC11045222 DOI: 10.7554/elife.89601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
We are unresponsive during slow-wave sleep but continue monitoring external events for survival. Our brain wakens us when danger is imminent. If events are non-threatening, our brain might store them for later consideration to improve decision-making. To test this hypothesis, we examined whether novel vocabulary consisting of simultaneously played pseudowords and translation words are encoded/stored during sleep, and which neural-electrical events facilitate encoding/storage. An algorithm for brain-state-dependent stimulation selectively targeted word pairs to slow-wave peaks or troughs. Retrieval tests were given 12 and 36 hr later. These tests required decisions regarding the semantic category of previously sleep-played pseudowords. The sleep-played vocabulary influenced awake decision-making 36 hr later, if targeted to troughs. The words' linguistic processing raised neural complexity. The words' semantic-associative encoding was supported by increased theta power during the ensuing peak. Fast-spindle power ramped up during a second peak likely aiding consolidation. Hence, new vocabulary played during slow-wave sleep was stored and influenced decision-making days later.
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Affiliation(s)
| | - Simon Ruch
- Institute of Psychology, University of BernBernSwitzerland
- Faculty of Psychology, UniDistance SuisseBrigSwitzerland
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2
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Henke K, Ruch S. Unconscious processing effects manifest only if conscious processing is excluded. Cogn Neurosci 2024; 15:73-74. [PMID: 38666549 DOI: 10.1080/17588928.2024.2343658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Indexed: 05/31/2024]
Abstract
In their discussion paper Steinkrauss and Slotnick argue against a role for the hippocampus in unconscious memory formation and retrieval. Unfortunately, they omitted highly relevant evidence that supports a role for the hippocampus in unconscious memory. They criticize four articles, two from our laboratory, pointing out long-known confounds like residual consciousness. We uncover these reproaches as untrue allegations. In our own interest, we prevented conscious mnemonic processing because reliable unconscious memory effects manifest only if consciousness is completely excluded, and because we always knew that residual consciousness would be our Achilles heel for the proponents of the 'explicit memory dogma.'
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Affiliation(s)
- Katharina Henke
- Institute of Psychology, University of Bern, Bern, Switzerland
| | - Simon Ruch
- Faculty of Psychology, UniDistance Suisse, Brig, Switzerland
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3
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Steinkrauss AC, Slotnick SD. Is implicit memory associated with the hippocampus? Cogn Neurosci 2024; 15:56-70. [PMID: 38368598 DOI: 10.1080/17588928.2024.2315816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/18/2024] [Indexed: 02/20/2024]
Abstract
According to the traditional memory-systems view, the hippocampus is critical during explicit (conscious) long-term memory, whereas other brain regions support implicit (nonconscious) memory. In the last two decades, some fMRI studies have reported hippocampal activity during implicit memory tasks. The aim of the present discussion paper was to identify whether any implicit memory fMRI studies have provided convincing evidence that the hippocampus is associated with nonconscious processes without being confounded by conscious processes. Experimental protocol and analysis parameters included the stimulus type(s), task(s), measures of subjective awareness, explicit memory accuracy, the relevant fMRI contrast(s) or analysis, and confound(s). A systematic review was conducted to identify implicit memory studies that reported fMRI activity in the hippocampus. After applying exclusion criteria, 13 articles remained for analysis. We found that there were no implicit memory fMRI studies where subjective awareness was absent, explicit memory performance was at chance, and there were no confounds that could have driven the observed hippocampal activity. The confounds included explicit memory (including false memory), imbalanced attentional states between conditions (yielding activation of the default-mode network), imbalanced stimuli between conditions, and differential novelty. As such, not a single fMRI study provided convincing evidence that implicit memory was associated with the hippocampus. Neuropsychological evidence was also considered, and implicit memory deficits were caused by factors known to disrupt brain regions beyond the hippocampus, such that the behavioral effects could not be attributed to this region. The present results indicate that implicit memory is not associated with the hippocampus.
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Affiliation(s)
- Ashley C Steinkrauss
- Department of Psychology and Neuroscience, Boston College, Chestnut Hill, MA, USA
| | - Scott D Slotnick
- Department of Psychology and Neuroscience, Boston College, Chestnut Hill, MA, USA
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4
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Züst MA. Dismissing the role of the hippocampus in implicit memory is special pleading. Cogn Neurosci 2024; 15:83-84. [PMID: 38647224 DOI: 10.1080/17588928.2024.2343663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Indexed: 04/25/2024]
Abstract
Steinkrauss and Slotnick (this issue) argue against hippocampal involvement in implicit memory, bringing up some important considerations. Their critique, however, exhibits significant flaws. The argumentation is based on an ill-defined key concept of 'implicit memory,' and important theoretical context is missed. Potential confounds are brought to bear against a rather narrow selection of studies, often without explaining how exactly the studies are biased. Refining the conceptual scope, including a broader range of literature, and arguing more inclusively would provide more nuanced insights into the hippocampus's role in implicit memory.
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Affiliation(s)
- Marc Alain Züst
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
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5
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Anderson MC, Subbulakshmi S. Amnesia in healthy people via hippocampal inhibition: A new forgetting mechanism. Q J Exp Psychol (Hove) 2024; 77:1-13. [PMID: 37691157 DOI: 10.1177/17470218231202728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Structural damage to the hippocampus gives rise to a severe memory deficit for personal experiences known as organic amnesia. Remarkably, such structural damage may not be the only way of creating amnesia; windows of amnesia can also arise when people deliberately disengage from memory via a process known as retrieval suppression. In this review, we discuss how retrieval suppression induces systemic inhibition of the hippocampus, creating "amnesic shadow" intervals in people's memory for their personal experiences. When new memories are encoded or older memories are reactivated during this amnesic shadow, these memories are disrupted, and such disruption even arises when older memories are subliminally cued. Evidence suggests that the systemic inhibition of the hippocampus during retrieval suppression that gives rise to the amnesic shadow may be mediated by engagement of hippocampal GABAergic inhibitory interneurons. Similar amnesic shadow effects are observed during working memory tasks like the n-back, which also induce notable hippocampal downregulation. We discuss our recent proposal that cognitive operations that require the disengagement of memory retrieval, such as retrieval suppression, are capable of mnemonic process inhibition (the inhibition of mnemonic processes such as encoding, consolidation, and retrieval and not simply individual memories). We suggest that people engage mnemonic process inhibition whenever they shift attention from internal processes to demanding perceptual-motor tasks that may otherwise be disrupted by distraction from our inner world. This hitherto unstudied model of inhibition is a missing step in understanding what happens when attentional shifts occur between internally and externally oriented processes to facilitate goal-directed behaviour. This process constitutes an important novel mechanism underlying the forgetting of life events.
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Affiliation(s)
- Michael C Anderson
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - S Subbulakshmi
- MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
- Department of Psychology, Stanford University, Stanford, CA, USA
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6
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Zher-Wen, Yu R. Unconscious integration: Current evidence for integrative processing under subliminal conditions. Br J Psychol 2023; 114:430-456. [PMID: 36689339 DOI: 10.1111/bjop.12631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
Integrative processing is traditionally believed to be dependent on consciousness. While earlier studies within the last decade reported many types of integration under subliminal conditions (i.e. without perceptual awareness), these findings are widely challenged recently. This review evaluates the current evidence for 10 types of subliminal integration that are widely studied: arithmetic processing, object-context integration, multi-word processing, same-different processing, multisensory integration and 5 different types of associative learning. Potential methodological issues concerning awareness measures are also taken into account. It is concluded that while there is currently no reliable evidence for subliminal integration, this does not necessarily refute 'unconscious' integration defined through non-subliminal (e.g. implicit) approaches.
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Affiliation(s)
- Zher-Wen
- Department of Management, Hong Kong Baptist University, Hong Kong, China.,Department of Psychology, National University of Singapore, Singapore City, Singapore
| | - Rongjun Yu
- Department of Management, Hong Kong Baptist University, Hong Kong, China
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7
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Flanagin VL, Klinkowski S, Brodt S, Graetsch M, Roselli C, Glasauer S, Gais S. The precuneus as a central node in declarative memory retrieval. Cereb Cortex 2023; 33:5981-5990. [PMID: 36610736 DOI: 10.1093/cercor/bhac476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 11/11/2022] [Accepted: 11/17/2022] [Indexed: 01/09/2023] Open
Abstract
Both, the hippocampal formation and the neocortex are contributing to declarative memory, but their functional specialization remains unclear. We investigated the differential contribution of both memory systems during free recall of word lists. In total, 21 women and 17 men studied the same list but with the help of different encoding associations. Participants associated the words either sequentially with the previous word on the list, with spatial locations on a well-known path, or with unique autobiographical events. After intensive rehearsal, subjects recalled the words during functional magnetic resonance imaging (fMRI). Common activity to all three types of encoding associations was identified in the posterior parietal cortex, in particular in the precuneus. Additionally, when associating spatial or autobiographical material, retrosplenial cortex activity was elicited during word list recall, while hippocampal activity emerged only for autobiographically associated words. These findings support a general, critical function of the precuneus in episodic memory storage and retrieval. The encoding-retrieval repetitions during learning seem to have accelerated hippocampus-independence and lead to direct neocortical integration in the sequentially associated and spatially associated word list tasks. During recall of words associated with autobiographical memories, the hippocampus might add spatiotemporal information supporting detailed scenic and contextual memories.
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Affiliation(s)
- Virginia L Flanagin
- Bernstein Center for Computational Neuroscience, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany.,IFB-LMU, Dept. of Neurology, Marchioninistr. 15, 81377 München, Germany
| | - Svenja Klinkowski
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Silcherstr. 5, 72076 Tübingen, Germany
| | - Svenja Brodt
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Silcherstr. 5, 72076 Tübingen, Germany
| | - Melanie Graetsch
- General and Experimental Psychology, Ludwig Maximilians University München, Leopoldstr. 13, 80802 München, Germany
| | - Carolina Roselli
- General and Experimental Psychology, Ludwig Maximilians University München, Leopoldstr. 13, 80802 München, Germany
| | - Stefan Glasauer
- Bernstein Center for Computational Neuroscience, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany.,Computational Neuroscience, Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz 1, 01968 Senftenberg, Germany
| | - Steffen Gais
- Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Silcherstr. 5, 72076 Tübingen, Germany
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8
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Pang DKF, Elntib S. Further evidence and theoretical framework for a subliminal sensory buffer store (SSBS). Conscious Cogn 2023; 107:103452. [PMID: 36508898 DOI: 10.1016/j.concog.2022.103452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022]
Abstract
We recently provided evidence that strongly masked stimuli are not erased or overwritten but are briefly stored in a subliminal sensory buffer store (SSBS), where information can accumulate through repetition and become consciously accessible. SSBS supports a direct prediction made by the global workspace theory of consciousness (GWT) and has implications on discussions about conscious overflow and the problem of the criterion. Here we show that the presentation sequence and the time from the target presentation to evaluation does not significantly impact perception. We suggest that selected information from this subliminal sensory buffer store is transferred into a type of supraliminal short-term memory that keeps stable representations for longer durations with full conscious access. We argue that the level of conscious access of memory storage has a greater impact on subsequent reportability than initial phenomenology and needs to be included more prominently in discussions on perception and consciousness.
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Affiliation(s)
- Damian K F Pang
- School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool L69 3BX, the United Kingdom of Great Britain and Northern Ireland.
| | - Stamatis Elntib
- Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool L69 3BX, the United Kingdom of Great Britain and Northern Ireland; School of Psychology and Counselling, Faculty of Arts and Social Sciences, The Open University, the United Kingdom of Great Britain and Northern Ireland
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9
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Pacozzi L, Knüsel L, Ruch S, Henke K. Inverse forgetting in unconscious episodic memory. Sci Rep 2022; 12:20595. [PMID: 36446829 PMCID: PMC9709067 DOI: 10.1038/s41598-022-25100-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Forming memories of experienced episodes calls upon the episodic memory system. Episodic encoding may proceed with and without awareness of episodes. While up to 60% of consciously encoded episodes are forgotten after 10 h, the fate of unconsciously encoded episodes is unknown. Here we track over 10 h, which are filled with sleep or daytime activities, the retention of unconsciously and consciously experienced episodes. The episodes were displayed in cartoon clips that were presented weakly and strongly masked for conscious and unconscious encoding, respectively. Clip retention was tested for distinct clips directly after encoding, 3 min and 10 h after encoding using a forced-choice test that demands deliberate responses in both consciousness conditions. When encoding was conscious, retrieval accuracy decreased by 25% from 3 min to 10 h, irrespective of sleep or wakefulness. When encoding was unconscious, retrieval accuracy increased from 3 min to 10 h and depended on sleep. Hence, opposite to the classic forgetting curve, unconsciously acquired episodic memories strengthen over time and hinge on sleep on the day of learning to gain influence over human behavior.
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Affiliation(s)
- Luca Pacozzi
- grid.5734.50000 0001 0726 5157Institute of Psychology, University of Bern, 3012 Bern, Switzerland
| | - Leona Knüsel
- grid.5734.50000 0001 0726 5157Institute of Psychology, University of Bern, 3012 Bern, Switzerland
| | - Simon Ruch
- grid.10392.390000 0001 2190 1447Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, University Hospital and University of Tuebingen, 72076 Tübingen, Germany
| | - Katharina Henke
- grid.5734.50000 0001 0726 5157Institute of Psychology, University of Bern, 3012 Bern, Switzerland
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10
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Inducing forgetting of unwanted memories through subliminal reactivation. Nat Commun 2022; 13:6496. [PMID: 36310181 PMCID: PMC9618560 DOI: 10.1038/s41467-022-34091-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 10/13/2022] [Indexed: 12/25/2022] Open
Abstract
Processes that might facilitate the forgetting of unwanted experiences typically require the actual or imagined re-exposure to reminders of the event, which is aversive and carries risks to people. But it is unclear whether awareness of aversive content is necessary for effective voluntary forgetting. Disrupting hippocampal function through retrieval suppression induces an amnesic shadow that impairs the encoding and stabilization of unrelated memories that are activated near in time to people's effort to suppress retrieval. Building on this mechanism, here we successfully disrupt retention of unpleasant memories by subliminally reactivating them within this amnesic shadow. Critically, whereas unconscious forgetting occurs on these affective memories, the amnesic shadow itself is induced by conscious suppression of unrelated and benign neutral memories, avoiding conscious re-exposure of unwelcome content. Combining the amnesic shadow with subliminal reactivation may offer a new approach to voluntary forgetting that bypasses the unpleasantness in conscious exposure to unwanted memories.
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11
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Jablonowski J, Rose M. The functional dissociation of posterior parietal regions during multimodal memory formation. Hum Brain Mapp 2022; 43:3469-3485. [PMID: 35397137 PMCID: PMC9248313 DOI: 10.1002/hbm.25861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/14/2022] [Accepted: 03/22/2022] [Indexed: 01/15/2023] Open
Abstract
The incidental acquisition of multimodal associations is a key memory function for everyday life. While the posterior parietal cortex has been frequently shown to be involved for these memory functions, ventral and dorsal regions revealed differences in their functional recruitment and the precise difference in multimodal memory processing with respect to the associative process has not been differentiated. Using an incidental multimodal learning task, we isolated the associative process during multimodal learning and recollection. The result of the present functional magnetic resonance imaging (fMRI) study demonstrated that during both learning and recollection a clear functional differentiation between ventral and dorsal posterior parietal regions was found and can be related directly to the associative process. The recruitment of a ventral region, the angular gyrus, was specific for learning and recollection of multimodal associations. In contrast, a dorsal region, the superior parietal lobule, could be attributed to memory guided attentional processing. Independent of the memory stage, we assumed a general role for the angular gyrus in the generation of associative representations and updating of fixed association, episodic memory.
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Affiliation(s)
- Julia Jablonowski
- NeuroImage Nord, Department for Systems Neuroscience, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Michael Rose
- NeuroImage Nord, Department for Systems Neuroscience, University Medical Center Hamburg Eppendorf, Hamburg, Germany
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12
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Abstract
Since the first description of the case of H.M. in the mid-1950s, the debate over the contribution of the mesial temporal lobe (MTL) to human memory functioning has not ceased to stimulate new experimental work and the development of new theoretical models. The early demonstration that despite their devastating memory loss patients with hippocampal damage are still able to learn a number of visuo-motor and visuo-perceptual skills at a normal rate and to be normally primed by verbal and visual material suggested that the term "memory" is actually an umbrella concept that includes very different brain plasticity phenomena and that MTL damage actually impairs only one of these. Subsequent research, which capitalized on a detailed anatomical description of MTL structures and on the close analysis of memory-related phenomena, tried to define the unique role of the MTL structures in brain plasticity and in the government of human behavior. A first hypothesis identified this role in the conscious forms of memory as opposed to implicit ones. In the last two decades, the emphasis has moved to the relational role of the hippocampus in binding together different pieces of unimodal information to provide unitary, multimodal representations of personal experiences.
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Affiliation(s)
- Giovanni A Carlesimo
- Department of Systems Medicine, Tor Vergata University, Rome, Italy; Clinical and Behavioral Neurology Laboratory, I.R.C.C.S. Santa Lucia Foundation, Rome, Italy.
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13
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Schneider E, Züst MA, Wuethrich S, Schmidig F, Klöppel S, Wiest R, Ruch S, Henke K. Larger capacity for unconscious versus conscious episodic memory. Curr Biol 2021; 31:3551-3563.e9. [PMID: 34256016 DOI: 10.1016/j.cub.2021.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 01/29/2021] [Accepted: 06/03/2021] [Indexed: 11/28/2022]
Abstract
Episodic memory is the memory for experienced events. A peak competence of episodic memory is the mental combination of events to infer commonalities. Inferring commonalities may proceed with and without consciousness of events. Yet what distinguishes conscious from unconscious inference? This question inspired nine experiments that featured strongly and weakly masked cartoon clips presented for unconscious and conscious inference. Each clip featured a scene with a visually impenetrable hiding place. Five animals crossed the scene one-by-one consecutively. One animal trajectory represented one event. The animals moved through the hiding place, where they might linger or not. The participants' task was to observe the animals' entrances and exits to maintain a mental record of which animals hid simultaneously. We manipulated information load to explore capacity limits. Memory of inferences was tested immediately, 3.5 or 6 min following encoding. The participants retrieved inferences well when encoding was conscious. When encoding was unconscious, the participants needed to respond intuitively. Only habitually intuitive decision makers exhibited a significant delayed retrieval of inferences drawn unconsciously. Their unconscious retrieval performance did not drop significantly with increasing information load, while conscious retrieval performance dropped significantly. A working memory network, including hippocampus, was activated during both conscious and unconscious inference and correlated with retrieval success. An episodic retrieval network, including hippocampus, was activated during both conscious and unconscious retrieval of inferences and correlated with retrieval success. Only conscious encoding/retrieval recruited additional brain regions outside these networks. Hence, levels of consciousness influenced the memories' behavioral impact, memory capacity, and the neural representational code.
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Affiliation(s)
- Else Schneider
- Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Marc Alain Züst
- Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland; University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bolligenstraße 111, 3000 Bern, Switzerland
| | - Sergej Wuethrich
- Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Flavio Schmidig
- Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Stefan Klöppel
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bolligenstraße 111, 3000 Bern, Switzerland
| | - Roland Wiest
- Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Freiburgstrasse 18, 3010 Bern, Switzerland
| | - Simon Ruch
- Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Katharina Henke
- Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland.
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14
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Schwab S, Afyouni S, Chen Y, Han Z, Guo Q, Dierks T, Wahlund LO, Grieder M. Functional Connectivity Alterations of the Temporal Lobe and Hippocampus in Semantic Dementia and Alzheimer's Disease. J Alzheimers Dis 2021; 76:1461-1475. [PMID: 32651312 PMCID: PMC7504988 DOI: 10.3233/jad-191113] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Semantic memory impairments in semantic dementia are attributed to atrophy and functional disruption of the anterior temporal lobes. In contrast, the posterior medial temporal neurodegeneration found in Alzheimer's disease is associated with episodic memory disturbance. The two dementia subtypes share hippocampal deterioration, despite a relatively spared episodic memory in semantic dementia. OBJECTIVE To unravel mutual and divergent functional alterations in Alzheimer's disease and semantic dementia, we assessed functional connectivity between temporal lobe regions in Alzheimer's disease (n = 16), semantic dementia (n = 23), and healthy controls (n = 17). METHODS In an exploratory study, we used a functional parcellation of the temporal cortex to extract time series from 66 regions for correlation analysis. RESULTS Apart from differing connections between Alzheimer's disease and semantic dementia that yielded reduced functional connectivity, we identified a common pathway between the right anterior temporal lobe and the right orbitofrontal cortex in both dementia subtypes. This disconnectivity might be related to social knowledge deficits as part of semantic memory decline. However, such interpretations are preferably made in a holistic context of disease-specific semantic impairments and functional connectivity changes. CONCLUSION Despite a major limitation owed to unbalanced databases between study groups, this study provides a preliminary picture of the brain's functional disconnectivity in Alzheimer's disease and semantic dementia. Future studies are needed to replicate findings of a common pathway with consistent diagnostic criteria and neuropsychological evaluation, balanced designs, and matched data MRI acquisition procedures.
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Affiliation(s)
- Simon Schwab
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom.,Translational Research Center, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
| | - Soroosh Afyouni
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
| | - Yan Chen
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Zaizhu Han
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Qihao Guo
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Thomas Dierks
- Translational Research Center, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
| | - Lars-Olof Wahlund
- Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Division of Clinical Geriatrics, Stockholm, Sweden
| | - Matthias Grieder
- Translational Research Center, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
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15
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Pang DKF, Elntib S. Strongly masked content retained in memory made accessible through repetition. Sci Rep 2021; 11:10284. [PMID: 33986370 PMCID: PMC8119432 DOI: 10.1038/s41598-021-89512-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/21/2021] [Indexed: 02/03/2023] Open
Abstract
A growing body of evidence indicates that information can be stored even in the absence of conscious awareness. Despite these findings, unconscious memory is still poorly understood with limited evidence for unconscious iconic memory storage. Here we show that strongly masked visual data can be stored and accumulate to elicit clear perception. We used a repetition method across a wide range of conditions (Experiment 1) and a more focused follow-up experiment with enhanced masking conditions (Experiment 2). Information was stored despite being masked, demonstrating that masking did not erase or overwrite memory traces but limited perception. We examined the temporal properties and found that stored information followed a gradual but rapid decay. Extraction of meaningful information was severely impaired after 300 ms, and most data was lost after 700 ms. Our findings are congruent with theories of consciousness that are based on an integration of subliminal information and support theoretical predictions based on the global workspace theory of consciousness, especially the existence of an implicit iconic memory buffer store.
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Affiliation(s)
- Damian K. F. Pang
- grid.10025.360000 0004 1936 8470Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool, L69 3BX UK ,grid.25879.310000 0004 1936 8972School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Stamatis Elntib
- grid.10025.360000 0004 1936 8470Department of Psychological Sciences, Institute of Psychology, Health and Society, University of Liverpool, Liverpool, L69 3BX UK
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16
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Yu Y, Wang X, Yang J, Qiu J. The role of the MTG in negative emotional processing in young adults with autistic-like traits: A fMRI task study. J Affect Disord 2020; 276:890-897. [PMID: 32739707 DOI: 10.1016/j.jad.2020.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/20/2020] [Accepted: 07/06/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Few previous studies explored negative emotion processing in autistic-like traits people using task-based fMRI. In this study, we applied task fMRI to determine the relationship between negative emotion processing and social skill within autistic-like traits people. aimed to find which brain areas specificity play a key role in emotional processing. METHODS 106 of Chinese individuals measured with AQ. Then applied emotion regulation task to explore the difference in brain activation and functional connectivity in individuals with autistic traits. RESULTS The results showed increased activation in the right middle temporal gyrus (MTG). The mediation analysis showed the right MTG mediates the relationship between autistic-like traits and negative emotion. Generalized psychophysiological interaction (gPPI) analysis also suggested that the right MTG shows significant functional connectivity with the left parahippocampal gyrus (PHG) and left precuneus cortex. LIMITATIONS Our sample are university students, there may have a bias in the sample compared to sub-average and have no differences between the gender, we will broaden the sample size and take the gender into account. We use two conditions as our focused theme, we want to use a more specific task to explore negative emotion in autistic-like traits people. CONCLUSIONS The results showed that the right MTG was an important brain region in individuals with autistic-like traits, and our study provides a wider discussion about autism brain activation and functional connectivity patterns and the use the MTG as a hallmark in individuals with autistic-like traits.
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Affiliation(s)
- Yaxu Yu
- School of Psychology, Southwest University, Chongqing 400715, China; Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Xiaoqin Wang
- School of Psychology, Southwest University, Chongqing 400715, China; Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Junyi Yang
- School of education science, Xinyang Normal University, Henan, China
| | - Jiang Qiu
- School of Psychology, Southwest University, Chongqing 400715, China; Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China; Southwest University Branch, Collaborative Innovation Center of Assessment Toward Basic Education Quality at Beijing Normal University, China.
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Loper AJ, Ramos AA, Hamdan AC. Fidelity of visual long-term memory in the ageing process ( Fidelidad de la memoria visual a largo plazo en el proceso de envejecimiento). STUDIES IN PSYCHOLOGY 2020. [DOI: 10.1080/02109395.2020.1794715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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18
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Yaxu Y, Ren Z, Ward J, Jiang Q. Atypical Brain Structures as a Function of Gray Matter Volume (GMV) and Gray Matter Density (GMD) in Young Adults Relating to Autism Spectrum Traits. Front Psychol 2020; 11:523. [PMID: 32322224 PMCID: PMC7158890 DOI: 10.3389/fpsyg.2020.00523] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 03/05/2020] [Indexed: 12/03/2022] Open
Abstract
Individuals with autistic traits are those who present in the normal population with characteristics of social, communication, personality, and cognitive impairments but do not meet the clinical threshold for autism spectrum disorder (ASD). Most studies have focused on the abnormalities in ASD patients rather than on individuals with autistic traits. In this study, we focused on the behaviors of a large sample (N = 401) of Chinese individuals with different levels of autistic traits, measured using the Autism Spectrum Quotient, and applied voxel-based morphometry (VBM) to determine their association to differences in brain structure. The results mainly showed that the correlation between gray matter volume (GMV) and gray matter density of the brain and the Autism Spectrum Quotient was significant in these regions: the right middle frontal gyrus, which are involved in social processing and social reasoning; the left parahippocampal gyrus, which is involved in socioemotional behaviors and unconscious relational memory encoding; and the right superior parietal lobule, which are involved in cognitive control and the ability to show attention to detail. These findings reveal that people with autistic traits in the normal population have atypical development in GMV and gray matter density, which may affect their social functioning and communication ability.
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Affiliation(s)
- Yu Yaxu
- School of Psychology, Southwest University, Chongqing, China.,Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Zhiting Ren
- School of Psychology, Southwest University, Chongqing, China.,Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Jamie Ward
- School of Psychology, University of Sussex, Brighton, United Kingdom.,Sackler Centre for Consciousness Science, University of Sussex, Brighton, United Kingdom
| | - Qiu Jiang
- School of Psychology, Southwest University, Chongqing, China.,Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
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Huang Y, Yaple ZA, Yu R. Goal-oriented and habitual decisions: Neural signatures of model-based and model-free learning. Neuroimage 2020; 215:116834. [PMID: 32283275 DOI: 10.1016/j.neuroimage.2020.116834] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 03/03/2020] [Accepted: 04/08/2020] [Indexed: 11/26/2022] Open
Abstract
Human decision-making is mainly driven by two fundamental learning processes: a slow, deliberative, goal-directed model-based process that maps out the potential outcomes of all options and a rapid habitual model-free process that enables reflexive repetition of previously successful choices. Although many model-informed neuroimaging studies have examined the neural correlates of model-based and model-free learning, the concordant activity among these two processes remains unclear. We used quantitative meta-analyses of functional magnetic resonance imaging experiments to identify the concordant activity pertaining to model-based and model-free learning over a range of reward-related paradigms. We found that: 1) both processes yielded concordant ventral striatum activity, 2) model-based learning activated the medial prefrontal cortex and orbital frontal cortex, and 3) model-free learning specifically activated the left globus pallidus and right caudate head. Our findings suggest that model-free and model-based decision making engage overlapping yet distinct neural regions. These stereotaxic maps improve our understanding of how deliberative goal-directed and reflexive habitual learning are implemented in the brain.
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Affiliation(s)
- Yi Huang
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Zachary A Yaple
- Department of Psychology, National University of Singapore, Singapore
| | - Rongjun Yu
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Psychology, National University of Singapore, Singapore.
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20
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Tanguay AFN, Palombo DJ, Atance CM, Renoult L, Davidson PSR. Scrutinizing the grey areas of declarative memory: Do the self-reference and temporal orientation of a trait knowledge task modulate the Late Positive Component (LPC)? Neuropsychologia 2020; 142:107444. [PMID: 32246950 DOI: 10.1016/j.neuropsychologia.2020.107444] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 03/22/2020] [Accepted: 03/23/2020] [Indexed: 11/27/2022]
Abstract
Knowledge about the future self may engage cognitive processes typically ascribed to episodic memory, such as awareness of the future self as an extension of the current self (i.e., autonoetic awareness) and the construction of future events. In a prior study (Tanguay et al., 2018), temporal orientation influenced the Late Positive Component (LPC), an ERP correlate of recollection. The LPC amplitude for present traits was intermediate between semantic and episodic memory, whereas thinking about one's future traits produced a larger LPC amplitude that was similar to episodic memory. Here, we examined further the effect of temporal orientation on the LPC amplitude and investigated if it was influenced by whether knowledge concerns the self or another person, with the proximity of the other being considered. Participants verified whether traits (e.g., Enthusiastic) were true of themselves and the "other," both now and in the future. Proximity of the other person was manipulated between subjects, such that participants either thought about the typical traits of a close friend (n = 31), or those of their age group more broadly (n = 35). Self-reference and temporal orientation interacted: The LPC amplitude for future knowledge was larger than for present knowledge, but only for the self. This effect of temporal orientation was not observed when participants thought about the traits of other people. The proximity of the other person did not modify these effects. Future-oriented cognition can engage different cognitive processes depending on self-reference; knowledge about the personal future increased the LPC amplitude unlike thinking about the future of other people. Our findings strengthen the notion of self-knowledge as a grey area between semantic and episodic memory.
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Affiliation(s)
- Annick F N Tanguay
- School of Psychology, University of Ottawa, Ottawa, Canada; Rotman Research Institute, Baycrest, Toronto, Canada.
| | - Daniela J Palombo
- Department of Psychology, University of British Columbia, Vancouver, Canada
| | | | - Louis Renoult
- School of Psychology, University of East Anglia, Norwich, UK
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21
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Loprinzi PD, Gilbert M, Robinson G, Dickerson B. Experimental Investigation Examining the Effects of Acute Exercise on Implicit Memory Function. EUROPES JOURNAL OF PSYCHOLOGY 2019; 15:700-716. [PMID: 33680155 PMCID: PMC7909193 DOI: 10.5964/ejop.v15i4.1837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 03/17/2019] [Indexed: 11/20/2022]
Abstract
Emerging work suggests that acute exercise can enhance explicit memory function. Minimal research, however, has examined whether acute exercise is associated with implicit memory, which was the purpose of this study. Three separate experimental studies were computed (N = 120; Mean age = 21). In Experiment 1, participants were randomly assigned to either a moderate-intensity bout of acute exercise (15-minute) or engaged in a seated control task (15-minute), followed by the completion of a word-fragmentation implicit memory task. Experiment 2 replicated Experiment 1, but instead employed a higher-intensity exercise protocol. For Experiment 3, participants were randomly assigned to either a moderate-intensity bout of acute exercise (15-minute) or engaged in a seated control task (15-minute), followed by the completion of a real world, 3-dimensional implicit memory task. For Experiment 1, the exercise and control groups, respectively, had an implicit memory score of 7.0 (0.5) and 7.5 (0.6) (t(38) = 0.67, p = .51). For Experiment 2, the exercise and control groups, respectively, had an implicit memory score of 6.9 (1.9) and 7.8 (2.4) (t(38) = 1.27, p = .21). These findings suggest that exercise, and the intensity of exercise, does not alter implicit memory from a word fragmentation task. For Experiment 3, the exercise and control groups, respectively, had a discrimination implicit memory index score of 0.48 (0.18) and 0.29 (0.32) (t(38) = 2.16, p = .03). In conclusion, acute exercise does not influence a commonly used laboratory-based assessment of implicit memory but may enhance real world-related implicit memory function.
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Affiliation(s)
- Paul D Loprinzi
- Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, Oxford, MS, USA
| | - Morgan Gilbert
- Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, Oxford, MS, USA
| | - Gina Robinson
- Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, Oxford, MS, USA
| | - Briahna Dickerson
- Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, Oxford, MS, USA
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22
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Rozier C, Seidel Malkinson T, Hasboun D, Baulac M, Adam C, Lehongre K, Clémenceau S, Navarro V, Naccache L. Conscious and unconscious expectancy effects: A behavioral, scalp and intracranial electroencephalography study. Clin Neurophysiol 2019; 131:385-400. [PMID: 31865140 DOI: 10.1016/j.clinph.2019.10.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/04/2019] [Accepted: 10/16/2019] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The scope of unconscious cognition stretched its limits dramatically during the last 40 years, yet most unconscious processes and representations that have been described so far are fleeting and very short-lived, whereas conscious representations can be actively maintained in working memory for a virtually unlimited period. In the present work we aimed at exploring conscious and unconscious lasting (>1 second) expectancy effects. METHODS In a series of four experiments we engaged participants in the foreperiod paradigm while using both unmasked and masked cues that were informative about the presence/absence of an upcoming target. We recorded behavioral responses, high-density scalp EEG (Exp. 2a), and intra-cranial EEG (Exp. 2b). RESULTS While conscious expectancy was associated with a large behavioral effect (~150 ms), unconscious expectancy effect was significant but much smaller (4 ms). Both conscious and unconscious expectancy Contingent Negative Variations (CNVs) originated from temporal cortices, but only the late component of conscious CNV originated from an additional source located in the vicinity of mesio-frontal areas and supplementary motor areas. Finally, only conscious expectancy was accessible to introspection. CONCLUSIONS Both unmasked and masked cues had an impact on response times and on brain activity. SIGNIFICANCE These results support a two-stage model of the underlying mechanisms of expectancy.
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Affiliation(s)
- Camille Rozier
- Sorbonne Université, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France; INSERM, U 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013 Paris, France
| | - Tal Seidel Malkinson
- Sorbonne Université, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France; INSERM, U 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013 Paris, France
| | - Dominique Hasboun
- Sorbonne Université, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France
| | - Michel Baulac
- Sorbonne Université, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France; AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, Paris, France
| | - Claude Adam
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, Paris, France
| | - Katia Lehongre
- Institut du Cerveau et de la Moelle épinière, CENIR, Paris, France
| | - Stéphane Clémenceau
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurosurgery, Paris, France
| | - Vincent Navarro
- Sorbonne Université, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France; INSERM, U 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013 Paris, France; AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, Paris, France; AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurophysiology, Paris, France
| | - Lionel Naccache
- Sorbonne Université, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France; INSERM, U 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013 Paris, France; AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, Paris, France; AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurophysiology, Paris, France.
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Kim H. Neural correlates of explicit and implicit memory at encoding and retrieval: A unified framework and meta-analysis of functional neuroimaging studies. Biol Psychol 2019; 145:96-111. [DOI: 10.1016/j.biopsycho.2019.04.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/14/2019] [Accepted: 04/17/2019] [Indexed: 10/26/2022]
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Abstract
Increasing evidence indicates that the subjective experience of recollection is diminished in autism spectrum disorder (ASD) compared to neurotypical individuals. The neurocognitive basis of this difference in how past events are re-experienced has been debated and various theoretical accounts have been proposed to date. Although each existing theory may capture particular features of memory in ASD, recent research questions whether any of these explanations are alone sufficient or indeed fully supported. This review first briefly considers the cognitive neuroscience of how episodic recollection operates in the neurotypical population, informing predictions about the encoding and retrieval mechanisms that might function atypically in ASD. We then review existing research on recollection in ASD, which has often not distinguished between different theoretical explanations. Recent evidence suggests a distinct difficulty engaging recollective retrieval processes, specifically the ability to consciously reconstruct and monitor a past experience, which is likely underpinned by altered functional interactions between neurocognitive systems rather than brain region-specific or process-specific dysfunction. This integrative approach serves to highlight how memory research in ASD may enhance our understanding of memory processes and networks in the typical brain. We make suggestions for future research that are important for further specifying the neurocognitive basis of episodic recollection in ASD and linking such difficulties to social developmental and educational outcomes.
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25
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Affiliation(s)
- Felipe De Brigard
- Department of Philosophy, Department of Psychology and Neuroscience, Center for Cognitive Neuroscience, Duke Institute for Brain Sciences, Duke University, Durham, NC, USA
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26
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Martínez JF, Trujillo C, Arévalo A, Ibáñez A, Cardona JF. Assessment of Conjunctive Binding in Aging: A Promising Approach for Alzheimer’s Disease Detection. J Alzheimers Dis 2019; 69:71-81. [DOI: 10.3233/jad-181154] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | | | - Analía Arévalo
- Department of Neurology, University of São Paulo Medical School, São Paulo, Brazil
| | - Agustín Ibáñez
- Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina
- National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
- Center for Social and Cognitive Neuroscience (CSCN), School of Psychology, Universidad Adolfo Ibanez, Santiago, Chile
- Centre of Excellence in Cognition and its Disorders, Australian Research Council (ACR), Sydney, Australia
| | - Juan F. Cardona
- Instituto de Psicología, Universidad del Valle, Cali, Colombia
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27
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Loprinzi PD. An integrated model of acute exercise on memory function. Med Hypotheses 2019; 126:51-59. [PMID: 31010500 DOI: 10.1016/j.mehy.2019.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/03/2019] [Accepted: 03/21/2019] [Indexed: 12/17/2022]
Abstract
Memory is a complex cognition that plays a critical role in daily functioning. This review discusses the dynamic effects of acute exercise on memory function, via a hypothesized exercise-memory interaction model, taking into consideration multiple memory systems and exercise parameters.
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Affiliation(s)
- Paul D Loprinzi
- Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA.
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28
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Züst MA, Ruch S, Wiest R, Henke K. Implicit Vocabulary Learning during Sleep Is Bound to Slow-Wave Peaks. Curr Biol 2019; 29:541-553.e7. [DOI: 10.1016/j.cub.2018.12.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 09/25/2018] [Accepted: 12/20/2018] [Indexed: 01/13/2023]
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29
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Wuethrich S, Hannula DE, Mast FW, Henke K. Subliminal encoding and flexible retrieval of objects in scenes. Hippocampus 2018; 28:633-643. [PMID: 29704287 PMCID: PMC6282531 DOI: 10.1002/hipo.22957] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 10/05/2017] [Accepted: 04/24/2018] [Indexed: 01/05/2023]
Abstract
Our episodic memory stores what happened when and where in life. Episodic memory requires the rapid formation and flexible retrieval of where things are located in space. Consciousness of the encoding scene is considered crucial for episodic memory formation. Here, we question the necessity of consciousness and hypothesize that humans can form unconscious episodic memories. Participants were presented with subliminal scenes, that is, scenes invisible to the conscious mind. The scenes displayed objects at certain locations for participants to form unconscious object-in-space memories. Later, the same scenes were presented supraliminally, that is, visibly, for retrieval testing. Scenes were presented absent the objects and rotated by 90°-270° in perspective to assess the representational flexibility of unconsciously formed memories. During the test phase, participants performed a forced-choice task that required them to place an object in one of two highlighted scene locations and their eye movements were recorded. Evaluation of the eye tracking data revealed that participants remembered object locations unconsciously, irrespective of changes in viewing perspective. This effect of gaze was related to correct placements of objects in scenes, and an intuitive decision style was necessary for unconscious memories to influence intentional behavior to a significant degree. We conclude that conscious perception is not mandatory for spatial episodic memory formation.
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Affiliation(s)
- Sergej Wuethrich
- Institute of Psychology, University of Bern, Fabrikstrasse 8, Bern 3012, Switzerland.,Center for Cognition, Learning and Memory, University of Bern, Fabrikstrasse 8, Bern 3012, Switzerland
| | - Deborah E Hannula
- Department of Psychology, University of Wisconsin-Milwaukee, 224 Garland Hall, 2441 Hartford Ave, Milwaukee, Wisconsin 53211
| | - Fred W Mast
- Institute of Psychology, University of Bern, Fabrikstrasse 8, Bern 3012, Switzerland.,Center for Cognition, Learning and Memory, University of Bern, Fabrikstrasse 8, Bern 3012, Switzerland
| | - Katharina Henke
- Institute of Psychology, University of Bern, Fabrikstrasse 8, Bern 3012, Switzerland.,Center for Cognition, Learning and Memory, University of Bern, Fabrikstrasse 8, Bern 3012, Switzerland
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30
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Reber TP, Samimizad B, Mormann F. Cue discriminability predicts instrumental conditioning. Conscious Cogn 2018; 61:49-60. [DOI: 10.1016/j.concog.2018.03.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 03/20/2018] [Accepted: 03/25/2018] [Indexed: 11/25/2022]
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Goldstone A, Mayhew SD, Hale JR, Wilson RS, Bagshaw AP. Thalamic functional connectivity and its association with behavioral performance in older age. Brain Behav 2018; 8:e00943. [PMID: 29670825 PMCID: PMC5893345 DOI: 10.1002/brb3.943] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/19/2017] [Accepted: 01/12/2018] [Indexed: 12/23/2022] Open
Abstract
Introduction Despite the thalamus' dense connectivity with both cortical and subcortical structures, few studies have specifically investigated how thalamic connectivity changes with age and how such changes are associated with behavior. This study investigated the effect of age on thalamo-cortical and thalamo-hippocampal functional connectivity (FC) and the association between thalamic FC and visual-spatial memory and reaction time (RT) performance in older adults. Methods Resting-state functional magnetic resonance images were obtained from younger (n = 20) and older (n = 20) adults. A seed-based approach was used to assess the FC between the thalamus and (1) sensory resting-state networks; (2) the hippocampus. Participants also completed visual-spatial memory and RT tasks, from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Results Older adults exhibited a loss of specificity in the FC between sensory thalamic subregions and corresponding sensory cortex. Greater thalamo-motor FC in older adults was associated with faster RTs. Furthermore, older adults exhibited greater thalamo-hippocampal FC compared to younger adults, which was greatest for those with the poorest visual-spatial memory performance. Conclusion Although older adults exhibited poorer visual-spatial memory and slower reaction times compared to younger adults, "good" and "poorer" older performers exhibited different patterns of thalamo-cortical and thalamo-hippocampal FC. These results highlight the potential role of thalamic connectivity in supporting reaction times and memory in aging. Furthermore, these results highlight the importance of including the thalamus in studies of aging to fully understand how brain changes with age may be associated with behavior.
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Affiliation(s)
- Aimée Goldstone
- Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
- School of PsychologyUniversity of BirminghamBirminghamUK
| | - Stephen D. Mayhew
- Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
- School of PsychologyUniversity of BirminghamBirminghamUK
| | - Joanne R. Hale
- Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
- School of PsychologyUniversity of BirminghamBirminghamUK
| | - Rebecca S. Wilson
- Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
- School of PsychologyUniversity of BirminghamBirminghamUK
| | - Andrew P. Bagshaw
- Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
- School of PsychologyUniversity of BirminghamBirminghamUK
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Meier B, Fanger S, Toller G, Matter S, Müri R, Gutbrod K. Amnesic patients have residual prospective memory capacities. Clin Neuropsychol 2018; 33:606-621. [PMID: 29436258 DOI: 10.1080/13854046.2018.1438516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To investigate, in two separate studies, whether amnesic patients with a severe memory impairment can learn to perform a habitual prospective memory task when they receive immediate feedback on prospective memory failures (Study 1) and whether amnesic patients are able to benefit from previous habitual prospective memory performance after a 24-h retention interval. METHOD A prospective memory task was embedded in a lexical decision task (Study 1) and in a perceptual discrimination task (Study 2). Performance was compared across test halves. Participants received immediate performance feedback on prospective memory failures that served as a reminder for the prospective memory task. A retest was performed after 24 h in Study 2, but without immediate feedback in the first test half. RESULTS In Study 1, amnesic patients performed at a lower level than the control group, but they improved significantly across the experiment. In Study 2, the results of the first session replicated this pattern. The results of the second session showed a performance breakdown in amnesic patients. However, one single reminder was enough to boost performance again on the level of the second part of day one. CONCLUSIONS This indicates that amnesic patients have residual prospective memory capacities and that providing immediate feedback is a promising strategy to draw on these capacities.
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Affiliation(s)
- Beat Meier
- a Institute of Psychology , University of Bern , Bern , Switzerland
| | - Severin Fanger
- a Institute of Psychology , University of Bern , Bern , Switzerland
| | - Giannina Toller
- a Institute of Psychology , University of Bern , Bern , Switzerland
| | - Sibylle Matter
- a Institute of Psychology , University of Bern , Bern , Switzerland
| | - René Müri
- b Department of Neurology , University of Bern , Bern , Switzerland.,c Department of Cognitive and Restorative Neurology , Bern University Hospital , Bern , Switzerland
| | - Klemens Gutbrod
- b Department of Neurology , University of Bern , Bern , Switzerland.,c Department of Cognitive and Restorative Neurology , Bern University Hospital , Bern , Switzerland
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Ruch S, Herbert E, Henke K. Subliminally and Supraliminally Acquired Long-Term Memories Jointly Bias Delayed Decisions. Front Psychol 2017; 8:1542. [PMID: 28955268 PMCID: PMC5600932 DOI: 10.3389/fpsyg.2017.01542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 08/24/2017] [Indexed: 11/13/2022] Open
Abstract
Common wisdom and scientific evidence suggest that good decisions require conscious deliberation. But growing evidence demonstrates that not only conscious but also unconscious thoughts influence decision-making. Here, we hypothesize that both consciously and unconsciously acquired memories guide decisions. Our experiment measured the influence of subliminally and supraliminally presented information on delayed (30-40 min) decision-making. Participants were presented with subliminal pairs of faces and written occupations for unconscious encoding. Following a delay of 20 min, participants consciously (re-)encoded the same faces now presented supraliminally along with either the same written occupations, occupations congruous to the subliminally presented occupations (same wage-category), or incongruous occupations (opposite wage-category). To measure decision-making, participants viewed the same faces again (with occupations absent) and decided on the putative income of each person: low, low-average, high-average, or high. Participants were encouraged to decide spontaneously and intuitively. Hence, the decision task was an implicit or indirect test of relational memory. If conscious thought alone guided decisions (= H0), supraliminal information should determine decision outcomes independently of the encoded subliminal information. This was, however, not the case. Instead, both unconsciously and consciously encoded memories influenced decisions: identical unconscious and conscious memories exerted the strongest bias on income decisions, while both incongruous and congruous (i.e., non-identical) subliminally and supraliminally formed memories canceled each other out leaving no bias on decisions. Importantly, the increased decision bias following the formation of identical unconscious and conscious memories and the reduced decision bias following to the formation of non-identical memories were determined relative to a control condition, where conscious memory formation alone could influence decisions. In view of the much weaker representational strength of subliminally vs. supraliminally formed memories, their long-lasting impact on decision-making is noteworthy.
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Affiliation(s)
- Simon Ruch
- Department of Psychology, University of BernBern, Switzerland.,Center for Cognition, Learning and Memory, University of BernBern, Switzerland
| | - Elizabeth Herbert
- School of Physiology, Pharmacology and Neuroscience, University of BristolBristol, United Kingdom
| | - Katharina Henke
- Department of Psychology, University of BernBern, Switzerland.,Center for Cognition, Learning and Memory, University of BernBern, Switzerland
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Pajkert A, Finke C, Shing YL, Hoffmann M, Sommer W, Heekeren HR, Ploner CJ. Memory integration in humans with hippocampal lesions. Hippocampus 2017; 27:1230-1238. [DOI: 10.1002/hipo.22766] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 07/06/2017] [Accepted: 07/28/2017] [Indexed: 01/03/2023]
Affiliation(s)
- Anna Pajkert
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin D-10117 Germany
| | - Carsten Finke
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin D-10117 Germany
- Berlin School of Mind & Brain; Humboldt-Universität zu Berlin; Berlin D-10117 Germany
| | - Yee Lee Shing
- Max Planck Institute for Human Development; Center for Lifespan Psychology; Berlin D-14195 Germany
- Division of Psychology, Faculty of Natural Sciences; University of Stirling; Scotland FK94LA United Kingdom
| | - Martina Hoffmann
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin D-10117 Germany
| | - Werner Sommer
- Department of Biological Psychology and Psychophysiology, Institute of Psychology; Humboldt-Universität zu Berlin; Berlin D-10099 Germany
| | - Hauke R. Heekeren
- Department of Education and Psychology; Freie Universität Berlin; Berlin D-14195 Germany
| | - Christoph J. Ploner
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin D-10117 Germany
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35
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Bergström F, Eriksson J. Neural Evidence for Non-conscious Working Memory. Cereb Cortex 2017; 28:3217-3228. [DOI: 10.1093/cercor/bhx193] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Indexed: 12/24/2022] Open
Affiliation(s)
- Fredrik Bergström
- Umeå center for Functional Brain Imaging (UFBI), Umeå University, Sweden
- Department of Integrative Medical Biology, Physiology Section, Umeå University, Sweden
- Faculty of Psychology and Educational Sciences, University of Coimbra, Portugal
| | - Johan Eriksson
- Umeå center for Functional Brain Imaging (UFBI), Umeå University, Sweden
- Department of Integrative Medical Biology, Physiology Section, Umeå University, Sweden
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36
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Morrill GA, Kostellow AB, Gupta RK. Computational comparison of a calcium-dependent jellyfish protein (apoaequorin) and calmodulin-cholesterol in short-term memory maintenance. Neurosci Lett 2017; 642:113-118. [PMID: 28159636 DOI: 10.1016/j.neulet.2017.01.069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/15/2017] [Accepted: 01/30/2017] [Indexed: 12/21/2022]
Abstract
Memory reconsolidation and maintenance depend on calcium channels and on calcium/calmodulin-dependent kinases regulating protein turnover in the hippocampus. Ingestion of a jellyfish protein, apoaequorin, reportedly protects and/or improves verbal learning in adults and is currently widely advertised for use by the elderly. Apoaequorin is a member of the EF-hand calcium binding family of proteins that includes calmodulin. Calmodulin-1 (148 residues) differs from Apoaequorin (195 residues) in that it contains four rather than three Ca2+-binding sites and three rather than four cholesterol-binding (CRAC, CARC) domains. All three cholesterol-binding CARC domains in calmodulin have a high interaction affinity for cholesterol compared to only two high affinity CARC domains in apoaequorin. Both calmodulin and apoaequorin can form dimers with a potential of eight bound Ca2+ ions and six high affinity-bound cholesterol molecules in calmodulin with six bound Ca2+ ions and a mixed population of eight cholesterols bound to both CARC and CRAC domains in apoaqueorin. MEMSAT-SVM analysis indicates that both calmodulin and apoaqueorin have a pore-lining region. The Peptide-Cutter algorithm predicts that calmodulin-1 contains 11 trypsin-specific cleavage sites (compared to 21 in apoaqueorin), four of which are potentially blocked by cholesterol and three are within the Ca-binding domains and/or the pore-lining region. Three are clustered between the third and fourth Ca2+-binding sites. Only calmodulin pore-lining regions contain Ca2+ binding sites and as dimers may insert into the plasma membrane of neural cells and act as Ca2+ channels. In a dietary supplement, bound cholesterol may protect both apoaequorin and calmodulin from proteolysis in the gut as well as facilitate uptake across the blood-brain barrier. Our results suggest that a physiological calmodulin-cholesterol complex, not cholesterol-free jellyfish protein, may better serve as a dietary supplement to facilitate memory maintenance.
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Affiliation(s)
- Gene A Morrill
- Department of Physiology & Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA.
| | - Adele B Kostellow
- Department of Physiology & Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Raj K Gupta
- Department of Physiology & Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
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Ruch S, Züst MA, Henke K. Subliminal messages exert long-term effects on decision-making. Neurosci Conscious 2016; 2016:niw013. [PMID: 30386634 PMCID: PMC6204644 DOI: 10.1093/nc/niw013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 07/01/2016] [Accepted: 07/22/2016] [Indexed: 01/02/2023] Open
Abstract
Subliminal manipulation is often considered harmless because its effects typically decay within a second. So far, subliminal long-term effects on behavior were only observed in studies which repeatedly presented highly familiar information such as single words. These studies suggest that subliminal messages are only slowly stored and might not be stored at all if they provide novel, unfamiliar information. We speculated that subliminal messages might affect delayed decision-making especially if messages contain several pieces of novel information that must be relationally bound in long-term memory. Relational binding engages the hippocampal memory system, which can rapidly encode and durably store novel relations. Here, we hypothesized that subliminally presented stimulus pairs would be relationally processed influencing the direction of delayed conscious decisions. In experiment 1, subliminal face–occupation pairs affected conscious decisions about the income of these individuals almost half an hour later. In experiment 2, subliminal presentation of vocabulary of a foreign language enabled participants to later decide whether these foreign words are presented with correct or incorrect translations. Subliminal influence did not significantly decay if probed after 25 versus 15 min. This is unprecedented evidence of the longevity and impact of subliminal messages on conscious, rational decision-making.
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Affiliation(s)
- Simon Ruch
- Department of Psychology, University of Bern, Switzerland and Center for Cognition, Learning and Memory, University of Bern, Switzerland
| | - Marc Alain Züst
- Department of Psychology, University of Bern, Switzerland and Center for Cognition, Learning and Memory, University of Bern, Switzerland
| | - Katharina Henke
- Department of Psychology, University of Bern, Switzerland and Center for Cognition, Learning and Memory, University of Bern, Switzerland
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38
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Liang Y, Pertzov Y, Nicholas JM, Henley SMD, Crutch S, Woodward F, Leung K, Fox NC, Husain M. Visual short-term memory binding deficit in familial Alzheimer's disease. Cortex 2016; 78:150-164. [PMID: 27085491 PMCID: PMC4865502 DOI: 10.1016/j.cortex.2016.01.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 11/20/2015] [Accepted: 01/27/2016] [Indexed: 01/31/2023]
Abstract
Long-term episodic memory deficits in Alzheimer's disease (AD) are well characterised but, until recently, short-term memory (STM) function has attracted far less attention. We employed a recently-developed, delayed reproduction task which requires participants to reproduce precisely the remembered location of items they had seen only seconds previously. This paradigm provides not only a continuous measure of localization error in memory, but also an index of relational binding by determining the frequency with which an object is misplaced to the location of one of the other items held in memory. Such binding errors in STM have previously been found on this task to be sensitive to medial temporal lobe (MTL) damage in focal lesion cases. Twenty individuals with pathological mutations in presenilin 1 or amyloid precursor protein genes for familial Alzheimer's disease (FAD) were tested together with 62 healthy controls. Participants were assessed using the delayed reproduction memory task, a standard neuropsychological battery and structural MRI. Overall, FAD mutation carriers were worse than controls for object identity as well as in gross localization memory performance. Moreover, they showed greater misbinding of object identity and location than healthy controls. Thus they would often mislocalize a correctly-identified item to the location of one of the other items held in memory. Significantly, asymptomatic gene carriers - who performed similarly to healthy controls on standard neuropsychological tests - had a specific impairment in object-location binding, despite intact memory for object identity and location. Consistent with the hypothesis that the hippocampus is critically involved in relational binding regardless of memory duration, decreased hippocampal volume across FAD participants was significantly associated with deficits in object-location binding but not with recall precision for object identity or localization. Object-location binding may therefore provide a sensitive cognitive biomarker for MTL dysfunction in a range of diseases including AD.
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Affiliation(s)
- Yuying Liang
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK.
| | - Yoni Pertzov
- Department of Psychology, The Hebrew University of Jerusalem, Israel.
| | - Jennifer M Nicholas
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK; Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, UK.
| | - Susie M D Henley
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK.
| | - Sebastian Crutch
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK.
| | - Felix Woodward
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK.
| | - Kelvin Leung
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK.
| | - Nick C Fox
- Dementia Research Centre, Department of Neurodegenerative Diseases, UCL Institute of Neurology, London, UK.
| | - Masud Husain
- Nuffield Department of Clinical Neurosciences, University of Oxford, UK; Department of Experimental Psychology, University of Oxford, UK.
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Gomes CA, Figueiredo P, Mayes A. Priming for novel object associations: Neural differences from object item priming and equivalent forms of recognition. Hippocampus 2015; 26:472-91. [DOI: 10.1002/hipo.22537] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Carlos Alexandre Gomes
- Human Memory Laboratory, School of Psychological Sciences, University of Manchester; United Kingdom
- Department of Bioengineering; Instituto Superior Técnico, Technical University of Lisbon; Portugal
| | - Patrícia Figueiredo
- Department of Bioengineering; Instituto Superior Técnico, Technical University of Lisbon; Portugal
- Institute for Systems and Robotics (ISR/IST), LARSyS, Instituto Superior Técnico, Technical University of Lisbon; Portugal
| | - Andrew Mayes
- Human Memory Laboratory, School of Psychological Sciences, University of Manchester; United Kingdom
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40
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Relational Memory Is Evident in Eye Movement Behavior despite the Use of Subliminal Testing Methods. PLoS One 2015; 10:e0141677. [PMID: 26512726 PMCID: PMC4626025 DOI: 10.1371/journal.pone.0141677] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 10/12/2015] [Indexed: 11/19/2022] Open
Abstract
While it is generally agreed that perception can occur without awareness, there continues to be debate about the type of representational content that is accessible when awareness is minimized or eliminated. Most investigations that have addressed this issue evaluate access to well-learned representations. Far fewer studies have evaluated whether or not associations encountered just once prior to testing might also be accessed and influence behavior. Here, eye movements were used to examine whether or not memory for studied relationships is evident following the presentation of subliminal cues. Participants assigned to experimental or control groups studied scene-face pairs and test trials evaluated implicit and explicit memory for these pairs. Each test trial began with a subliminal scene cue, followed by three visible studied faces. For experimental group participants, one face was the studied associate of the scene (implicit test); for controls none were a match. Subsequently, the display containing a match was presented to both groups, but now it was preceded by a visible scene cue (explicit test). Eye movements were recorded and recognition memory responses were made. Participants in the experimental group looked disproportionately at matching faces on implicit test trials and participants from both groups looked disproportionately at matching faces on explicit test trials, even when that face had not been successfully identified as the associate. Critically, implicit memory-based viewing effects seemed not to depend on residual awareness of subliminal scene cues, as subjective and objective measures indicated that scenes were successfully masked from view. The reported outcomes indicate that memory for studied relationships can be expressed in eye movement behavior without awareness.
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41
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Bergström F, Eriksson J. The conjunction of non-consciously perceived object identity and spatial position can be retained during a visual short-term memory task. Front Psychol 2015; 6:1470. [PMID: 26483726 PMCID: PMC4588213 DOI: 10.3389/fpsyg.2015.01470] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 09/14/2015] [Indexed: 11/13/2022] Open
Abstract
Although non-consciously perceived information has previously been assumed to be short-lived (< 500 ms), recent findings show that non-consciously perceived information can be maintained for at least 15 s. Such findings can be explained as working memory without a conscious experience of the information to be retained. However, whether or not working memory can operate on non-consciously perceived information remains controversial, and little is known about the nature of such non-conscious visual short-term memory (VSTM). Here we used continuous flash suppression to render stimuli non-conscious, to investigate the properties of non-consciously perceived representations in delayed match-to-sample (DMS) tasks. In Experiment I we used variable delays (5 or 15 s) and found that performance was significantly better than chance and was unaffected by delay duration, thereby replicating previous findings. In Experiment II the DMS task required participants to combine information of spatial position and object identity on a trial-by-trial basis to successfully solve the task. We found that the conjunction of spatial position and object identity was retained, thereby verifying that non-conscious, trial-specific information can be maintained for prospective use. We conclude that our results are consistent with a working memory interpretation, but that more research is needed to verify this interpretation.
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Affiliation(s)
- Fredrik Bergström
- Umeå Center for Functional Brain Imaging, Umeå University Umeå, Sweden ; Department of Integrative Medical Biology, Physiology Section, Umeå University Umeå, Sweden
| | - Johan Eriksson
- Umeå Center for Functional Brain Imaging, Umeå University Umeå, Sweden ; Department of Integrative Medical Biology, Physiology Section, Umeå University Umeå, Sweden
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42
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Intracranial EEG correlates of implicit relational inference within the hippocampus. Hippocampus 2015; 26:54-66. [DOI: 10.1002/hipo.22490] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 06/24/2015] [Accepted: 06/24/2015] [Indexed: 11/07/2022]
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Horner AJ, Bisby JA, Bush D, Lin WJ, Burgess N. Evidence for holistic episodic recollection via hippocampal pattern completion. Nat Commun 2015; 6:7462. [PMID: 26136141 PMCID: PMC4506995 DOI: 10.1038/ncomms8462] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/12/2015] [Indexed: 11/09/2022] Open
Abstract
Recollection is thought to be the hallmark of episodic memory. Here we provide evidence that the hippocampus binds together the diverse elements forming an event, allowing holistic recollection via pattern completion of all elements. Participants learn complex ‘events' from multiple overlapping pairs of elements, and are tested on all pairwise associations. At encoding, element ‘types' (locations, people and objects/animals) produce activation in distinct neocortical regions, while hippocampal activity predicts memory performance for all within-event pairs. When retrieving a pairwise association, neocortical activity corresponding to all event elements is reinstated, including those incidental to the task. Participant's degree of incidental reinstatement correlates with their hippocampal activity. Our results suggest that event elements, represented in distinct neocortical regions, are bound into coherent ‘event engrams' in the hippocampus that enable episodic recollection—the re-experiencing or holistic retrieval of all aspects of an event—via a process of hippocampal pattern completion and neocortical reinstatement. The holistic retrieval of complex event memories is thought to be the hallmark of episodic memory. Here, the authors provide behavioural and neuroimaging evidence that the hippocampus binds together the elements forming an event to allow holistic episodic recollection via pattern completion of all elements.
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Affiliation(s)
- Aidan J Horner
- 1] UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK [2] UCL Institute of Neurology, Queen Square, London WC1 3BG, UK
| | - James A Bisby
- 1] UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK [2] UCL Institute of Neurology, Queen Square, London WC1 3BG, UK
| | - Daniel Bush
- 1] UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK [2] UCL Institute of Neurology, Queen Square, London WC1 3BG, UK
| | - Wen-Jing Lin
- 1] UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK [2] UCL Institute of Neurology, Queen Square, London WC1 3BG, UK
| | - Neil Burgess
- 1] UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK [2] UCL Institute of Neurology, Queen Square, London WC1 3BG, UK
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Focquaert F, Vanneste S. Autism spectrum traits in normal individuals: a preliminary VBM analysis. Front Hum Neurosci 2015; 9:264. [PMID: 26029082 PMCID: PMC4428126 DOI: 10.3389/fnhum.2015.00264] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/23/2015] [Indexed: 11/21/2022] Open
Abstract
In light of the new DSM-5 autism spectrum disorders diagnosis in which the autism spectrum reflects a group of neurodevelopmental disorders existing on a continuum from mild to severe expression of autistic traits, and recent empirical findings showing a continuous distribution of autistic traits in the general population, our voxel based morphometry study compares normal individuals with high autistic traits to normal individuals with low autistic traits. We hypothesize that normal individuals with high autistic traits in terms of empathizing and systemizing [high systemizing (HS)/low empathizing (LE)] share brain irregularities with individuals that fall within the clinical autism spectrum disorder. We find differences in several social brain network areas between our groups. Specifically, we find increased gray matter (GM) volume in the orbitofrontal cortex, the cuneus, the hippocampus and parahippocampus and reduced GM volume in the inferior temporal cortex, the insula, and the amygdala in our HS/LE individuals relative to our HE/LS (low autistic traits in terms of empathizing and systemizing) individuals.
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Affiliation(s)
- Farah Focquaert
- Department of Philosophy and Moral Sciences, Bioethics Institute Ghent, Ghent University Ghent, Belgium
| | - Sven Vanneste
- Lab for Clinical and Integrative Neuroscience, School of Behavioral and Brain Sciences, Callier Center for Communication Disorders, The University of Texas at Dallas Dallas, TX, USA
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45
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Züst MA, Colella P, Reber TP, Vuilleumier P, Hauf M, Ruch S, Henke K. Hippocampus is place of interaction between unconscious and conscious memories. PLoS One 2015; 10:e0122459. [PMID: 25826338 PMCID: PMC4380440 DOI: 10.1371/journal.pone.0122459] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/11/2015] [Indexed: 11/18/2022] Open
Abstract
Recent evidence suggests that humans can form and later retrieve new semantic relations unconsciously by way of hippocampus-the key structure also recruited for conscious relational (episodic) memory. If the hippocampus subserves both conscious and unconscious relational encoding/retrieval, one would expect the hippocampus to be place of unconscious-conscious interactions during memory retrieval. We tested this hypothesis in an fMRI experiment probing the interaction between the unconscious and conscious retrieval of face-associated information. For the establishment of unconscious relational memories, we presented subliminal (masked) combinations of unfamiliar faces and written occupations ("actor" or "politician"). At test, we presented the former subliminal faces, but now supraliminally, as cues for the reactivation of the unconsciously associated occupations. We hypothesized that unconscious reactivation of the associated occupation-actor or politician-would facilitate or inhibit the subsequent conscious retrieval of a celebrity's occupation, which was also actor or politician. Depending on whether the reactivated unconscious occupation was congruent or incongruent to the celebrity's occupation, we expected either quicker or delayed conscious retrieval process. Conscious retrieval was quicker in the congruent relative to a neutral baseline condition but not delayed in the incongruent condition. fMRI data collected during subliminal face-occupation encoding confirmed previous evidence that the hippocampus was interacting with neocortical storage sites of semantic knowledge to support relational encoding. fMRI data collected at test revealed that the facilitated conscious retrieval was paralleled by deactivations in the hippocampus and neocortical storage sites of semantic knowledge. We assume that the unconscious reactivation has pre-activated overlapping relational representations in the hippocampus reducing the neural effort for conscious retrieval. This finding supports the notion of synergistic interactions between conscious and unconscious relational memories in a common, cohesive hippocampal-neocortical memory space.
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Affiliation(s)
- Marc Alain Züst
- Department of Psychology, Division of Experimental Psychology and Neuropsychology, University of Bern, Bern, Switzerland
- Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland
- * E-mail:
| | - Patrizio Colella
- Department of Psychology, Division of Experimental Psychology and Neuropsychology, University of Bern, Bern, Switzerland
- Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland
| | - Thomas Peter Reber
- Department of Psychology, Division of Experimental Psychology and Neuropsychology, University of Bern, Bern, Switzerland
- Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland
| | - Patrik Vuilleumier
- Department of Neurosciences and Clinical Neurology, University of Geneva, Geneva, Switzerland
| | - Martinus Hauf
- Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Bern, Switzerland
| | - Simon Ruch
- Department of Psychology, Division of Experimental Psychology and Neuropsychology, University of Bern, Bern, Switzerland
- Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland
| | - Katharina Henke
- Department of Psychology, Division of Experimental Psychology and Neuropsychology, University of Bern, Bern, Switzerland
- Center for Cognition, Learning and Memory, University of Bern, Bern, Switzerland
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46
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Ryals AJ, Wang JX, Polnaszek KL, Voss JL. Hippocampal contribution to implicit configuration memory expressed via eye movements during scene exploration. Hippocampus 2015; 25:1028-41. [PMID: 25620526 DOI: 10.1002/hipo.22425] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 11/11/2022]
Abstract
Although hippocampus unequivocally supports explicit/declarative memory, fewer findings have demonstrated its role in implicit expressions of memory. We tested for hippocampal contributions to an implicit expression of configural/relational memory for complex scenes using eye-movement tracking during functional magnetic resonance imaging (fMRI) scanning. Participants studied scenes and were later tested using scenes that resembled study scenes in their overall feature configuration but comprised different elements. These configurally similar scenes were used to limit explicit memory, and were intermixed with new scenes that did not resemble studied scenes. Scene configuration memory was expressed through eye movements reflecting exploration overlap (EO), which is the viewing of the same scene locations at both study and test. EO reliably discriminated similar study-test scene pairs from study-new scene pairs, was reliably greater for similarity-based recognition hits than for misses, and correlated with hippocampal fMRI activity. In contrast, subjects could not reliably discriminate similar from new scenes by overt judgments, although ratings of familiarity were slightly higher for similar than new scenes. Hippocampal fMRI correlates of this weak explicit memory were distinct from EO-related activity. These findings collectively suggest that EO was an implicit expression of scene configuration memory associated with hippocampal activity. Visual exploration can therefore reflect implicit hippocampal-related memory processing that can be observed in eye-movement behavior during naturalistic scene viewing.
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Affiliation(s)
- Anthony J Ryals
- Department of Medical Social Sciences, Ken and Ruth Davee Department of Neurology, and Interdepartmental Neuroscience Program, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Jane X Wang
- Department of Medical Social Sciences, Ken and Ruth Davee Department of Neurology, and Interdepartmental Neuroscience Program, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Kelly L Polnaszek
- Department of Medical Social Sciences, Ken and Ruth Davee Department of Neurology, and Interdepartmental Neuroscience Program, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Joel L Voss
- Department of Medical Social Sciences, Ken and Ruth Davee Department of Neurology, and Interdepartmental Neuroscience Program, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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47
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Gomes CA, Mayes A. Does long-term object priming depend on the explicit detection of object identity at encoding? Front Psychol 2015; 6:270. [PMID: 25852594 PMCID: PMC4367169 DOI: 10.3389/fpsyg.2015.00270] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 02/23/2015] [Indexed: 11/13/2022] Open
Abstract
It is currently unclear whether objects have to be explicitly identified at encoding for reliable behavioral long-term object priming to occur. We conducted two experiments that investigated long-term object and non-object priming using a selective-attention encoding manipulation that reduces explicit object identification. In Experiment 1, participants either counted dots flashed within an object picture (shallow encoding) or engaged in an animacy task (deep encoding) at study, whereas, at test, they performed an object-decision task. Priming, as measured by reaction times (RTs), was observed for both types of encoding, and was of equivalent magnitude. In Experiment 2, non-object priming (faster RTs for studied relative to unstudied non-objects) was also obtained under the same selective-attention encoding manipulation as in Experiment 1, and the magnitude of the priming effect was equivalent between experiments. In contrast, we observed a linear decrement in recognition memory accuracy across conditions (deep encoding of Experiment 1 > shallow encoding Experiment 1 > shallow encoding of Experiment 2), suggesting that priming was not contaminated by explicit memory strategies. We argue that our results are more consistent with the identification/production framework than the perceptual/conceptual distinction, and we conclude that priming of pictures largely ignored at encoding can be subserved by the automatic retrieval of two types of instances: one at the motor level and another at an object-decision level.
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Affiliation(s)
- Carlos A. Gomes
- Human Memory Laboratory, School of Psychological Sciences, University of ManchesterManchester, UK
- Department of Psychology, Saarland University, SaarbrückenGermany
| | - Andrew Mayes
- Human Memory Laboratory, School of Psychological Sciences, University of ManchesterManchester, UK
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Veselis RA. Memory formation during anaesthesia: plausibility of a neurophysiological basis. Br J Anaesth 2015; 115 Suppl 1:i13-i19. [PMID: 25735711 DOI: 10.1093/bja/aev035] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
As opposed to conscious, personally relevant (explicit) memories that we can recall at will, implicit (unconscious) memories are prototypical of 'hidden' memory; memories that exist, but that we do not know we possess. Nevertheless, our behaviour can be affected by these memories; in fact, these memories allow us to function in an ever-changing world. It is still unclear from behavioural studies whether similar memories can be formed during anaesthesia. Thus, a relevant question is whether implicit memory formation is a realistic possibility during anaesthesia, considering the underlying neurophysiology. A different conceptualization of memory taxonomy is presented, the serial parallel independent model of Tulving, which focuses on dynamic information processing with interactions among different memory systems rather than static classification of different types of memories. The neurophysiological basis for subliminal information processing is considered in the context of brain function as embodied in network interactions. Function of sensory cortices and thalamic activity during anaesthesia are reviewed. The role of sensory and perisensory cortices, in particular the auditory cortex, in support of memory function is discussed. Although improbable, with the current knowledge of neurophysiology one cannot rule out the possibility of memory formation during anaesthesia.
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Affiliation(s)
- R A Veselis
- Department of Anesthesiology and Critical Care Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY, USA Department of Anesthesiology, Weill Cornell Medical College, 1300 York Avenue, New York, NY, USA
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Gomes CA, Montaldi D, Mayes A. The pupil as an indicator of unconscious memory: Introducing the pupil priming effect. Psychophysiology 2015; 52:754-69. [PMID: 25656874 DOI: 10.1111/psyp.12412] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 12/13/2014] [Indexed: 11/28/2022]
Abstract
We explored whether object behavioral priming and pupil changes occur in the absence of recognition memory. Experiment 1 found behavioral priming for unrecognized objects (Ms) regardless of whether they had been encoded perceptually or conceptually. Using the same perceptual encoding task, Experiment 2 showed greater pupil dilation for Ms than for correct rejections of unstudied objects (CRs) when reaction times were matched. In Experiment 3, there was relatively less pupil dilation for Ms than for similarly matched CRs when objects had been encoded conceptually. Mean/peak pupil dilation for CRs, but not Ms, increased in Experiment 3, in which novelty expectation was also reduced, and the pupillary time course for both Ms and CRs was distinct in the two experiments. These findings indicate that both behavioral and pupil memory occur for studied, but unrecognized stimuli, and suggest that encoding and novelty expectation modulate pupillary memory responses.
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Affiliation(s)
- Carlos Alexandre Gomes
- Human Memory Laboratory, School of Psychological Sciences, University of Manchester, Manchester, UK
| | - Daniela Montaldi
- Human Memory Laboratory, School of Psychological Sciences, University of Manchester, Manchester, UK
| | - Andrew Mayes
- Human Memory Laboratory, School of Psychological Sciences, University of Manchester, Manchester, UK
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Mayes A. The hippocampus is essential for completely unconscious as well as conscious flexible memories. Brain 2014; 137:3106-8. [DOI: 10.1093/brain/awu284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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