Unconscious relational encoding depends on hippocampus

Duss, Simone B.; Reber, Thomas P.; Hänggi, Jürgen; Schwab, Simon; Wiest, Roland; Müri, René M.; Brugger, Peter; Gutbrod, Klemens; Henke, Katharina

doi:10.1093/brain/awu270

Cited by 65 publications

(70 citation statements)

References 50 publications

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“…This trace strength level might be sufficient to support robust unconscious memory, which only falls to chance at lower trace strength levels. As Duss et al () recently found in support of this single system view for a relational kind of associative priming, both recognition and priming activated the hippocampus (a likely storage region), although much more activity was found for recognition, which was more sensitive to small hippocampal lesions, than priming. It is less clear, however, whether the kind of item priming identified here corresponds to a weaker level of the same storage system that supports corresponding item familiarity memory.…”

Section: Discussionmentioning

confidence: 71%

The pupil as an indicator of unconscious memory: Introducing the pupil priming effect

2015

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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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Section: Discussionmentioning

confidence: 71%

The pupil as an indicator of unconscious memory: Introducing the pupil priming effect

2015

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“…The paradigm that we have used here is a modification of a visual associative inference task that has repeatedly been used to study how the brain constructs memory representations that can flexibly be used for future behavior (Preston, Shrager, Dudukovic, & Gabrieli, ; Zeithamova and Preston, ; Zeithamova et al, ). Similar paradigms have incorporated information about value (Gerraty, Davidow, Wimmer, Kahn, & Shohamy, ; Murty, FeldmanHall, Hunter, Phelps, & Davachi, ; Wimmer and Shohamy, ) or used verbal material that was presented subliminally (Duss et al, ; Reber et al, ). Despite differences in stimulus material and the degree of consciousness of processing of to‐be‐remembered items, the results of these and other fMRI studies converge on a central role of the hippocampus within networks for memory integration (Palombo, Keane, & Verfaellie, ; Schlichting and Preston, ; Shohamy and Daw, ; Zeithamova et al, ).…”

Section: Discussionmentioning

confidence: 99%

Memory integration in humans with hippocampal lesions

et al. 2017

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Adaptive behavior frequently depends on inference from past experience. Recent studies suggest that the underlying process of integrating related memories may depend on interaction between hippocampus and prefrontal cortex. Here, we investigated how hippocampal damage affects memory integration. Subjects with mediotemporal lesions and healthy controls learned a set of overlapping AB- and BC-associations (object-face- and face-object pairs) and were then tested for memory of these associations ("direct" trials) and of inferential AC-associations ("indirect" trials). The experiment consisted of four encoding/retrieval cycles. In direct trials, performance of patients and controls was similar and stable across cycles. By contrast, in indirect trials, patients and controls showed distinct patterns of behavior. Whereas patients and controls initially showed only minor differences, controls increased performance across subsequent cycles, while patient performance decreased to chance level. Further analysis suggested that this deficit was not merely a consequence of impaired associative memory but rather resulted from an additional hippocampal contribution to memory integration. Our findings further suggest that contextual factors modulate this contribution. Patient deficits in more complex memory-guided behavior may depend on the flexible interaction of hippocampus-dependent and -independent mechanisms of memory integration.

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“…Declining memory performance is perhaps the cognitive deficit most commonly associated with advancing age (see Craik & Rose, 2012 and Khan, Martin‐Montanez, Navarro‐Lobato, & Muly, 2014 for reviews). While the hippocampus clearly plays a vital role in explicit (Riedel et al., 1999; Schacter, Alpert, Savage, Rauch, & Albert, 1996; Squire, 1992) and implicit (Duss et al., 2014) memory, the connectivity between the hippocampus and other brain regions, including the anterior thalamus, has also been implicated in supporting memory function (Aggleton & Brown, 1999; Aggleton et al., 2010; Child & Benarroch, 2013; Jankowski et al., 2013). Evidence from patients with thalamic infarcts supports the view that disrupted thalamo‐cortical structural connectivity is associated with memory problems (Serra et al., 2014), while functional connectivity (FC) strength between the dorsomedial nucleus of the thalamus and parts of the striatum has also been negatively associated with episodic memory functioning in 49‐ to 80‐year‐olds (Ystad, Eichele, Lundervold, & Lundervold, 2010).…”

Section: Introductionmentioning

confidence: 99%

Thalamic functional connectivity and its association with behavioral performance in older age

et al. 2018

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IntroductionDespite 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.MethodsResting‐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).ResultsOlder 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.ConclusionAlthough 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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Unconscious relational encoding depends on hippocampus

Cited by 65 publications

References 50 publications

The pupil as an indicator of unconscious memory: Introducing the pupil priming effect

The pupil as an indicator of unconscious memory: Introducing the pupil priming effect

Memory integration in humans with hippocampal lesions

Thalamic functional connectivity and its association with behavioral performance in older age

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