scholarly journals Effects of Left Inferior Prefrontal Stimulation on Episodic Memory Formation: A Two-Stage fMRI—rTMS Study

2004 ◽  
Vol 16 (2) ◽  
pp. 178-188 ◽  
Author(s):  
Stefan Köhler ◽  
Tomáš; Paus ◽  
Randy L. Buckner ◽  
Brenda Milner
Keyword(s):  
Recognition Memory ◽  
Episodic Memory ◽  
Memory Performance ◽  
Critical Role ◽  
Memory Formation ◽  
Frameless Stereotaxy ◽  
Successful Recovery ◽  
Neural Processes ◽  
Semantic Encoding ◽  
Brain Behavior

Successful recovery of words from episodic memory relies strongly on semantic processes at the time of encoding. Evidence from several functional magnetic resonance imaging (fMRI) studies has shown that changes in neural activity in the left inferior prefrontal cortex (LIPFC) during semantic encoding predict subsequent memory performance. This evidence has been taken to suggest that LIPFC plays a critical role in memory formation. Functional neuroimaging findings, however, do not establish a causal brain-behavior relationship. To determine whether there is a causal link between LIPFC involvement at encoding and subsequent success in memory performance, we conducted a two-part study in which we first used fMRI to localize encoding-related activation in LIPFC and then employed repetitive transcranial magnetic stimulation (rTMS) to manipulate neural processes in LIPFC during semantic encoding. To demonstrate the neuroanatomical specificity of any observed effect and to control for nonspecific rTMS side effects, we also stimulated neural processes in two control sites. Using frameless stereotaxy, we positioned the stimulation coil to target (1) the LIPF region that was activated during fMRI (mean xyz = −48 35 5); (2) the homologous righthemisphere region; and (3) an additional left parietal control site. At each site, “stimulated” items (600 msec of 7-Hz rTMS with Cadwell Round Coil) were intermixed with items presented without concurrent stimulation. Subsequently, subjects performed a recognition memory task for the words encountered. We found support for the predicted causal brain-behavior relationship, which was specific to LIPFC. When comparing recognition scores for stimulated items, normalized for variations in performance on nonstimulated trials, we found that words encoded under LIPFC stimulation were subsequently recognized with higher accuracy than words encoded under stimulation in the two cortical control sites. By contrast, no performance difference emerged when the two control sites were compared with each other. Based on additional analyses of the rTMS effects observed directly at the time of encoding (i.e., on semantic-decision performance), we suggest that LIPFC stimulation may have produced its effect on recognition memory, at least in part, through the triggering of more extensive processing of the stimulated items and an ensuing gain in item distinctiveness. Physiological processes of facilitation probably also contributed to the observed memory benefit. Together, these findings suggest that LIPFC does play a causal role in episodic memory formation.

Knowledge is power: prior knowledge aids memory formation for both congruent and incongruent events, but in different ways.

2017 ◽  
Author(s):  
Andrea Greve ◽  
Elisa Cooper ◽  
Roni Tibon ◽  
Richard Henson
Keyword(s):  
Episodic Memory ◽  
Prior Knowledge ◽  
Memory Performance ◽  
Memory Formation ◽  
Memory Test ◽  
World Knowledge ◽  
Apparent Paradox ◽  
Power Prior

Events that conform to our expectations, i.e, are congruent with our world knowledge or schemas, are better remembered than unrelated events. Yet events that conflict with schemas can also be remembered better. We examined this apparent paradox in four experiments, in which schemas were established by training ordinal relationships between randomly-paired objects, while episodic memory was tested for the number of objects on each trial. Better memory was found for both congruent and incongruent trials, relative to unrelated trials, producing memory performance that was a “U-shaped” function of congruency. Furthermore, the incongruency advantage, but not congruency advantage, emerged even if the information probed by the memory test was irrelevant to the schema, while the congruency advantage, but not incongruency advantage, also emerged after initial encoding. Schemas therefore augment episodic memory in multiple ways, depending on the match between novel and existing information.

scholarly journals Functional specialization of the medial temporal lobes in human recognition memory: dissociating effects of hippocampal vs parahippocampal damage

2020 ◽  
Author(s):  
Georgios P. D. Argyropoulos ◽  
Carola Dell’Acqua ◽  
Emily Butler ◽  
Clare Loane ◽  
Adriana Roca-Fernandez ◽  
...  
Keyword(s):  
Recognition Memory ◽  
Medial Temporal Lobe ◽  
Single Case ◽  
Memory Performance ◽  
Perirhinal Cortex ◽  
Process Models ◽  
Dual Process ◽  
Hippocampal Damage ◽  
Material Type ◽  
Brain Behavior

AbstractA central debate in the systems neuroscience of memory concerns whether different medial temporal lobe (MTL) structures support different processes or material-types in recognition memory. We tested a rare patient (Patient MH) with a perirhinal lesion that appeared to spare the hippocampus, using two recognition memory paradigms, each run separately with faces, scenes and words. Replicating reports of a previous case, Patient MH showed impaired familiarity and preserved recollection, relative to controls, with no evidence for any effect of material-type. Moreover, when compared with other amnesic patients, who had hippocampal lesions that appeared to spare the perirhinal cortex, Patient MH showed greater impairment on familiarity and less on recollection, forming a double dissociation. However, when replacing this traditional, binary categorization of patients with a parametric analysis that related memory performance to continuous measures of brain damage across all patients, we found a different pattern: while hippocampal damage predicted recollection, it was parahippocampal instead of perirhinal (or entorhinal) cortex volume that predicted familiarity. Furthermore, there was no evidence that these brain-behavior relationships were moderated by material-type, nor by laterality of damage. Thus, while our data provide the most compelling support yet for dual-process models of recognition memory, in which recollection and familiarity depend on different MTL structures, they suggest that familiarity depends more strongly upon the parahippocampal rather than perirhinal cortex. More generally, our study reinforces the need to go beyond single-case and group studies, and instead examine continuous brain-behavior relationships across larger patient groups.

scholarly journals Recognition Memory Dysfunction Relates to Hippocampal Subfield Volume: A Study of Cognitively Normal and Mildly Impaired Older Adults

2018 ◽  
Vol 74 (7) ◽  
pp. 1132-1141 ◽  
Author(s):  
Ilana J Bennett ◽  
Shauna M Stark ◽  
Craig E L Stark
Keyword(s):  
Older Adults ◽  
Recognition Memory ◽  
Episodic Memory ◽  
Dentate Gyrus ◽  
Memory Performance ◽  
Temporal Cortex ◽  
Memory Dysfunction ◽  
Cognitively Normal ◽  
Hippocampal Subfields ◽  
And Function

Abstract Objectives The current study examined recognition memory dysfunction and its neuroanatomical substrates in cognitively normal older adults and those diagnosed with mild cognitive impairment (MCI). Methods Participants completed the Mnemonic Similarity Task, which provides simultaneous measures of recognition memory and mnemonic discrimination. They also underwent structural neuroimaging to assess volume of medial temporal cortex and hippocampal subfields. Results As expected, individuals diagnosed with MCI had significantly worse recognition memory performance and reduced volume across medial temporal cortex and hippocampal subfields relative to cognitively normal older adults. After controlling for diagnostic group differences, however, recognition memory was significantly related to whole hippocampus volume, and to volume of the dentate gyrus/CA3 subfield in particular. Recognition memory was also related to mnemonic discrimination, a fundamental component of episodic memory that has previously been linked to dentate gyrus/CA3 structure and function. Discussion Results reveal that hippocampal subfield volume is sensitive to individual differences in recognition memory in older adults independent of clinical diagnosis. This supports the notion that episodic memory declines along a continuum within this age group, not just between diagnostic groups.

scholarly journals Distributed alpha networks underlie individual differences in memory performance

2016 ◽  
Author(s):  
Roy Cox ◽  
Anna C Schapiro ◽  
Robert Stickgold
Keyword(s):  
Individual Differences ◽  
Episodic Memory ◽  
Large Scale ◽  
Memory Performance ◽  
Oscillatory Activity ◽  
Neural Basis ◽  
Individual Memory ◽  
Optimal Information ◽  
Network Approaches ◽  
Brain Behavior

AbstractEpisodic memory, our ability to remember specific events, varies considerably across individuals. However, little is known about the neural basis of this variability. To address this issue, we investigated the role of distributed networks of oscillatory activity, as measured through electroencephalography (EEG). We observed that individual differences in alpha network structure reliably predict individual memory capacity. Specifically, individuals whose network profiles during encoding were most different from their resting state networks exhibited greatest subsequent memory performance, suggesting that optimal information processing requires substantial shifts in large-scale oscillatory organization. Furthermore, these results were not observed in circumscribed topographical regions or individual connections, indicating that distributed network approaches were more sensitive to functional processes than more conventional methods. These findings uncover a physiological correlate of individual differences in episodic memory and demonstrate the utility of multivariate EEG techniques to uncover brain-behavior correlates.

The interaction of working memory performance and episodic memory formation in patients with Korsakoff's amnesia

2012 ◽  
Vol 1433 ◽  
pp. 98-103 ◽  
Author(s):  
Bonnie van Geldorp ◽  
Heiko C. Bergmann ◽  
Johanna Robertson ◽  
Arie J. Wester ◽  
Roy P.C. Kessels
Keyword(s):  
Working Memory ◽  
Episodic Memory ◽  
Memory Performance ◽  
Memory Formation

scholarly journals Family history and APOE4 risk for Alzheimer’s Disease impact the neural correlates of episodic memory by early midlife

2017 ◽  
Author(s):  
M. N. Rajah ◽  
L. M. K. Wallace ◽  
E. Ankudowich ◽  
E. H. Yu ◽  
A. Swierkot ◽  
...  
Keyword(s):  
Risk Factors ◽  
Family History ◽  
Episodic Memory ◽  
Late Onset ◽  
Brain Activity ◽  
Memory Performance ◽  
Middle Aged ◽  
Brain Behavior ◽  
Context Memory ◽  
Encoding And Retrieval

AbstractEpisodic memory impairment is a consistent, pronounced deficit in pre-clinical stages of late-onset Alzheimer’s disease (AD). Individuals with risk factors for AD exhibit altered brain function several decades prior to the onset of AD-related symptoms. In the current event-related fMRI study of spatial context memory we tested the hypothesis that middle-aged adults (MA; 40-58yrs) with a family history of late onset AD (MA+FH), or a combined +FH and apolipoprotein E ε4 allele risk factors for AD (MA+FH+APOE4), will exhibit differences in encoding and retrieval-related brain activity, compared to – FH –APOE4 MA controls. We also hypothesized that the two at-risk MA groups will exhibit distinct patterns of correlation between brain activity and memory performance, compared to controls. To test these hypotheses we conducted multivariate task, and behavior, partial least squares analysis of fMRI data obtained during successful context encoding and retrieval. Our results indicate that even though there were no significant group differences in context memory performance, there were significant differences in brain activity and brain-behavior correlations involving hippocampus, inferior parietal cortex, cingulate, and precuneus in MA with AD risk factors, compared to controls. In addition, we observed that brain activity and brain-behavior correlations in anterior-medial PFC and in ventral visual cortex differentiated the two MA risk groups from each other, and from MAcontrols. Our results indicate that functional differences in episodic memory-related regions are present by early midlife in adults with +FH and +APOE-4 risk factors for late onset AD, compared to middle-aged controls.

scholarly journals Disentangling the roles of neocortical alpha/beta and hippocampal theta/gamma oscillations in human episodic memory formation

2020 ◽  
Author(s):  
Benjamin J. Griffiths ◽  
María Carmen Martín-Buro ◽  
Bernhard P. Staresina ◽  
Simon Hanslmayr
Keyword(s):  
Episodic Memory ◽  
Memory Performance ◽  
Empirical Support ◽  
Memory Formation ◽  
Information Representation ◽  
Gamma Phase ◽  
Beta Power ◽  
Alpha Beta ◽  
Phase Amplitude ◽  
Hippocampal Theta

AbstractEpisodic memory formation relies on at least two distinct capabilities: 1) our ability to process a vast amount of sensory information, and 2) our ability to bind these sensory representations together to form a coherent memory. The first process is thought to rely on a reduction in neocortical alpha/beta power, while the second is thought to be supported by hippocampal theta-gamma phase-amplitude coupling. However, most studies investigating human episodic memory use paradigms where the two cognitive capabilities overlap. As such, empirical support for the distinction of the two associated neural phenomena is lacking. Here, we addressed this by asking seventeen human participants (11 female, 6 male) to complete a sequence-learning paradigm that temporally separated information representation from mnemonic binding, while MEG recordings were acquired. We found that a decrease in neocortical alpha/beta power during the perception of the sequence correlated with enhanced memory performance. Similar power decreases during mnemonic binding, however, had no bearing on memory formation. In contrast, an increase in hippocampal theta/gamma phase-amplitude coupling during mnemonic binding correlated with enhanced memory performance, but similar coupling during sequence perception bared no relation to later memory performance. These results demonstrate that alpha/beta power decreases and hippocampal theta/gamma phase-amplitude coupling represent two temporally dissociable processes in episodic memory, with the former relating to information representation while the latter relates to mnemonic binding.

scholarly journals Components of episodic memory: the contribution of recollection and familiarity

2001 ◽  
Vol 356 (1413) ◽  
pp. 1363-1374 ◽  
Author(s):  
Andrew P. Yonelinas
Keyword(s):  
Recognition Memory ◽  
Episodic Memory ◽  
Memory Retrieval ◽  
Memory Performance ◽  
Qualitative Information ◽  
Recognition Memory Performance ◽  
Retrieval Processes ◽  
Cognitive Neuropsychological ◽  
Memory Confidence ◽  
Threshold Process

The examination of recognition memory confidence judgements indicates that there are two separate components or processes underlying episodic memory. A model that accounts for these results is described in which a recollection process and a familiarity process are assumed to contribute to recognition memory performance. Recollection is assumed to reflect a threshold process whereby qualitative information about the study event is retrieved, whereas familiarity reflects a classical signal–detection process whereby items exceeding a familiarity response criterion are accepted as having been studied. Evidence from cognitive, neuropsychological and neuroimaging studies indicate that the model is in agreement with the existing recognition results, and indicate that recollection and familiarity are behaviourally, neurally and phenomenologically distinct memory retrieval processes.

scholarly journals Single-trial Phase Entrainment of Theta Oscillations in Sensory Regions Predicts Human Associative Memory Performance

2018 ◽  
Author(s):  
Danying Wang ◽  
Andrew Clouter ◽  
Qiaoyu Chen ◽  
Kimron L. Shapiro ◽  
Simon Hanslmayr
Keyword(s):  
Episodic Memory ◽  
Auditory Cortex ◽  
Associative Memory ◽  
Memory Performance ◽  
Memory Formation ◽  
Theta Oscillations ◽  
Memory Representation ◽  
Relative Timing ◽  
Single Trial ◽  
Phase Offset

AbstractEpisodic memories are rich in sensory information and often contain integrated information from different sensory modalities. For instance, we can store memories of a recent concert with visual and auditory impressions being integrated in one episode. Theta oscillations have recently been implicated in playing a causal role synchronizing and effectively binding the different modalities together in memory. However, an open question is whether momentary fluctuations in theta synchronization predict the likelihood of associative memory formation for multisensory events. To address this question we presented movies and sounds with their luminance and volume modulated at theta (4 Hz), with a phase offset at 0° or 180° with respect to each other. This allowed us to entrain the visual and auditory cortex in a synchronous (0°) or asynchronous manner (180°). Participants were asked to remember the association between a movie and a sound while having their EEG activity recorded. Associative memory performance was significantly enhanced in the synchronous (0°) compared to the asynchronous (180°) condition. Source-level analysis demonstrated that the physical stimuli effectively entrained their respective cortical areas with a corresponding phase offset. Importantly, the strength of entrainment during encoding correlated with the efficacy of associative memory such that small phase differences between visual and auditory cortex predicted a high likelihood of correct retrieval in a later recall test. These findings suggest that theta oscillations serve a specific function in the episodic memory system: Binding the contents of different modalities into coherent memory episodes.Significance StatementHow multi-sensory experiences are bound to form a coherent episodic memory representation is one of the fundamental questions in human episodic memory research. Evidence from animal literature suggests that the relative timing between an input and theta oscillations in the hippocampus is crucial for memory formation. We precisely controlled the timing between visual and auditory stimuli and the neural oscillations at 4 Hz using a multisensory entrainment paradigm. Human associative memory formation depends on coincident timing between sensory streams processed by the corresponding brain regions. We provide evidence for a significant role of relative timing of neural theta activity in human episodic memory on a single trial level, which reveals a crucial mechanism underlying human episodic memory.

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