Event-related potentials (ERPs) were recorded to investigate the relationship between deep/shallow processing and memory encoding. Three major results were: (1) Under both processings of Chinese materials, the subsequent memory effects (Dm) were obtained. A late positive ERP elicited by words later recognized was larger than that elicited by words later forgotten. (2) The Dm effect was different between the two processings. The Dm effect for deep processing began at the front branch of N2 wave (230 280 ms), and more obvious held behind N2 from 395ms to 800ms. The Dm effect for shallow processing was obtained only from 345ms to 490ms. In addition, the Dm for deep processing was observed over frontal and fronto-central areas of scalps but over parietal and occipital areas for the shallow processing. Such results support the possibility that deep and shallow processing Dm effect may diverge. (3) The Dm effect was different from ERP differences between two processings. Such results support the speciality of Dm effect in memory encoding

相继记忆模式在记忆形成的脑认知成像研究领域应用广泛，已成为研究者探究大脑形成记忆时活动 的主要窗口。该文在介绍相继记忆模式及记忆形成过程的基础上，分析影响相继记忆效应大小和时空分布的因素，最后讨论内侧颞叶及前额叶神经网络中相关脑区如 何分工、协同支持情节记忆形成。情节记忆多维度特性导致该神经网络中有关区域表现出不同形式的相继记忆效应，因此，该文提出有效分离这些脑区在记忆形成中 如何分工及交互协同关系进行更为重要。

Neural indices of memory formation can be acquired by contrasting activity during study for items that are remembered or forgotten on a subsequent memory test. These “subsequent memory” effects vary with the stimulus types that are encoded, how they are encoded, the correspondences between study and test materials, and the time intervals between study and test phases. We investigated whether event-related potential (ERP) subsequent memory effects also vary with the content people must retrieve. Participants saw words on the left/right side of fixation, and made a drawing difficulty or pleasantness judgment to each. In separate test phases, participants were asked to remember study screen location, or which task judgment had been made. The ERP subsequent memory effects from these two tasks were functionally distinct, demonstrating for the first time that ERP subsequent memory effects dissociate according to what people are trying to retrieve.

The ability to remember the spatial context in which our experiences occur declines linearly across the adult lifespan. However, little is known about whether this source memory decline is associated with neural activity changes. In the present study, functional magnetic resonance imaging (fMRI) scans were recorded in young, middle-aged and old adults to investigate brain activity variations across the adult lifespan during encoding of subsequent spatial source memory retrieval. Twelve healthy individuals of both sexes were enrolled in each age group. During encoding, participants performed natural/artificial judgment of images of common objects that were randomly presented in one of the quadrants of the screen. During retrieval, the images presented at encoding were randomly mixed with new ones and displayed at the center of the screen. Participants judged whether each image was new or old and, if an image was old, they were instructed to indicate in which quadrant the image was presented in the encoding session. The contrast between study items that were later recognized and assigned a correct source judgment with those whose sources were subsequently forgotten revealed that positive subsequent memory effects disappear by middle age in the left medial orbitofrontal gyrus and appear in the left superior occipital gyrus. This under-recruitment and over-recruitment brain activity was also present in old adults. The results allowed us to identify the specific brain regions that first fail to encode spatial information into an episodic representation during the adult lifespan.

Aging effects on regional brain activation have been studied extensively to explain the gradual recollection failure that occurs with advancing age. However, little is known about the consequence of aging on the interaction among brain regions that support recollection. The purpose of this study was to examine effective connectivity at encoding and retrieval during successful and unsuccessful recollection in young and old adults. In particular, we analyzed a recollection network that is characterized by its susceptibility to aging effects by middle age or later, which is comprised of the occipital cortex, hippocampus and orbitofrontal cortex. Participants brains were scanned using functional magnetic resonance imaging while they performed a spatial source memory task. Dynamic causal modeling and Bayesian model selection revealed that subsequent recollection during encoding and recollection during retrieval modulated the influence of the orbitofrontal cortex on the hippocampus in both age groups; this particular connectivity was not modulated by unsuccessful encoding in either group. Successful encoding and retrieval of item-source associations modulated all connections within the network in old adults. The findings revealed that the orbitofrontal cortex influences processes in the hippocampus to ensure successful recollection, and aging alters the recollection network by engaging non-specialized connections.

Much research has demonstrated that aging is marked by decreased source memory relative to young adults, yet a smaller body of work has demonstrated that increasing the socioemotional content of source information may be one way to reduce age-related performance differences. Although dorsomedial prefrontal cortex (dmPFC) activity may support source memory among young and older adults, the extent to which one activates dorsal vs. ventral mPFC may reflect one's personal connection with incoming information. Because truth value may be one salient marker that impacts one's connection with information and allocation of attention toward incoming material, we investigated whether the perceived truth value of information differently impacts differences in mPFC activity associated with encoding source information, particularly with age. Twelve young (18 23 years) and 12 older adults (63 80 years) encoded true and false statements. Behavioral results showed similar memory performance between the age groups. With respect to neural activity associated with subsequent memory, young adults, relative to older adults, exhibited greater activity in dmPFC while older adults displayed enhanced ventromedial prefrontal cortex (vmPFC) and insula engagement relative to young. These results may potentially indicate that young adults focus on a general knowledge acquisition goal, while older adults focus on emotionally relevant aspects of the material. The findings demonstrate that age-related differences in recruitment of mPFC associated with encoding source information may in some circumstances underlie age-equivalent behavioral performance.

Abstract Differential neural activation at encoding can predict which stimuli will be subsequently remembered or forgotten, and memory deficits are pronounced in schizophrenia. We used event-related functional magnetic resonance imaging (fMRI) to investigate subsequent memory (SM) effects for visual fractals in patients with schizophrenia (n=26) and healthy controls (n=28). Participants incidentally encoded the fractals during an oddball task and 10min later they made old/new recognition memory judgments on 30 target fractals and 30 foil fractals. We found evidence for subsequent memory (SM, subsequently remembered>subsequently forgotten) effects on regional brain activation in both groups but with distinct patterns. Region of interest (ROI) analyses in controls demonstrated SM activation in both medial temporal lobe (MTL) and fusiform cortex (FF), whereas patients showed SM effects only in the FF. There were no significant between group differences in MTL activation; however, patients demonstrated greater FF activation than controls. Notably, greater FF activation during successful encoding was associated with more severe negative symptoms. Exploratory whole brain analyses in patients demonstrated SM activation in the occipital pole, lateral occipital cortex, left inferior temporal gyrus, and fusiform cortex; whereas in controls there was no significant activation that survived correction for multiple comparisons. Our findings suggest that patients, particularly those with prominent negative symptoms, may activate FF as a compensatory strategy to promote successful encoding, with relatively less reliance on MTL recruitment. Copyright 2014 Elsevier Ireland Ltd. All rights reserved.

Abstract Functional magnetic resonance imaging (fMRI) was employed to examine the effects of a study task manipulation on pre-stimulus activity in the hippocampus predictive of later successful recollection. Eighteen young participants were scanned while making either animacy or syllable judgments on visually presented study words. Cues presented before each word denoted which judgment should be made. Following the study phase, a surprise recognition memory test was administered in which each test item had to be endorsed as "Remembered," "Known," or "New." As expected, "deep" animacy judgments led to better memory for study items than did "shallow" syllable judgments. In both study tasks, pre-stimulus subsequent recollection effects were evident in the interval between the cue and the study item in bilateral anterior hippocampus. However, the direction of the effects differed according to the study task: whereas pre-stimulus hippocampal activity on animacy trials was greater for later recollected items than items judged old on the basis of familiarity (replicating prior findings), these effects reversed for syllable trials. We propose that the direction of pre-stimulus hippocampal subsequent memory effects depends on whether an optimal pre-stimulus task set facilitates study processing that is conducive or unconducive to the formation of contextually rich episodic memories. 2015 Wiley Periodicals, Inc.

According to cortical reinstatement accounts, neural processes engaged at the time of encoding are re-engaged at the time of memory retrieval. The temporal precision of event-related potentials (ERPs) has been exploited to assess this possibility, and in this study ERPs were acquired while people made memory judgments to visually presented words encoded in two different ways. There were reliable differences between the scalp distributions of the signatures of successful retrieval of different contents from 300 to 1100ms after stimulus presentation. Moreover, the scalp distributions of these content-sensitive effects changed during this period. These findings are, to our knowledge, the first demonstration in one study that ERPs reflect content-specific processing in two separable ways: first, via reinstatement, and second, via downstream processes that operate on recovered information in the service of memory judgments.

Abstract As event-related brain potential (ERP) researchers have increased the number of recording sites, they have gained further insights into the electrical activity in the neural networks underlying explicit memory. A review of the results of such ERP mapping studies suggests that there is good correspondence between ERP results and those from brain imaging studies that map hemodynamic changes. This concordance is important because the combination of the high temporal resolution of ERPs with the high spatial resolution of hemodynamic imaging methods will provide a greatly increased understanding of the spatio-temporal dynamics of the brain networks that encode and retrieve explicit memories. Copyright 2000 Wiley-Liss, Inc.

Women and men differ in the way they experience emotional events. Previous work has indicated that the impact of an emotional event depends on how it is anticipated. Separately, it has been shown that anticipation affects memory formation. Here, we assessed whether anticipatory brain activity influences the encoding of emotional events into long-term memory and, in addition, how biological sex affects the use of such activity. Electrical brain activity was recorded from the scalps of healthy men and women while they performed an incidental encoding task (indoor/outdoor judgments) on pleasant, unpleasant, and neutral pictures. Pictures were preceded by a cue that indicated the valence of the upcoming item. Memory was tested after a 20 min delay with a recognition task incorporating the remember/know procedure. Brain activity before picture onset predicted later memory of an event. Crucially, the role of anticipatory activity depended entirely on the valence of a picture and the sex of an individual. Right-lateralized anticipatory activity selectively influenced the encoding of unpleasant pictures in women, but not in men. These findings indicate that anticipatory processes influence the way in which women encode negative events into memory. The selective use of such activity may indicate that anticipatory activity is one mechanism by which individuals regulate their emotions.

Abstract It is difficult to pinpoint the border between perceptual and conceptual processing, despite their treatment as distinct entities in many studies of recognition memory. For instance, alteration of simple perceptual characteristics of a stimulus can radically change meaning, such as the color of bread changing from white to green. We sought to better understand the role of perceptual and conceptual processing in memory by identifying the effects of changing a basic perceptual feature (color) on behavioral and neural correlates of memory in circumstances when this change would be expected to either change the meaning of a stimulus or to have no effect on meaning (i.e., to influence conceptual processing or not). Abstract visual shapes ("squiggles") were colorized during study and presented during test in either the same color or a different color. Those squiggles that subjects found to resemble meaningful objects supported behavioral measures of conceptual priming, whereas meaningless squiggles did not. Further, changing color from study to test had a selective effect on behavioral correlates of priming for meaningful squiggles, indicating that color change altered conceptual processing. During a recognition memory test, color change altered event-related brain potential (ERP) correlates of memory for meaningful squiggles but not for meaningless squiggles. Specifically, color change reduced the amplitude of frontally distributed N400 potentials (FN400), implying that these potentials indicated conceptual processing during recognition memory that was sensitive to color change. In contrast, color change had no effect on FN400 correlates of recognition for meaningless squiggles, which were overall smaller in amplitude than for meaningful squiggles (further indicating that these potentials signal conceptual processing during recognition). Thus, merely changing the color of abstract visual shapes can alter their meaning, changing behavioral and neural correlates of memory. These findings are relevant to understanding similarities and distinctions between perceptual and conceptual processing as well as the functional interpretation of neural correlates of recognition memory.

Mood states have a strong impact on how we process incoming information. It has been proposed that positive mood facilitates elaborative, relational encoding, whereas negative mood promotes a more careful, stimulus-driven encoding style. Previous electrophysiological studies have linked successful information encoding to power increases in slow (30 Hz) gamma oscillations, as well as to power decreases in midrange (8-30 Hz) alpha/beta oscillations. Whether different mood states modulate encoding-related oscillations has not been investigated yet. In order to address this question, we used an experimental mood induction procedure and recorded electroencephalograms from 20 healthy participants while they performed a free recall memory task after positive and negative mood induction. We found distinct oscillatory patterns in positive and negative mood. Successful encoding in positive mood was accompanied by widespread power increases in the delta band, whereas encoding success in negative mood was specifically accompanied by frontal power decreases in the beta band. On the behavioral level, memory performance was enhanced in positive mood. Our findings show that mood differentially modulates the neural correlates of successful information encoding and thus contribute to an understanding of how mood shapes different processing styles.

The ability to recollect details about past events improves during childhood. Most researchers favor the view that this improvement depends largely on the development of the prefrontal cortex, which is thought to have a protracted course of development relative to the medial temporal lobes (MTL). The primary goal of the present study was to test the hypothesis that the development of detail recollection is also associated with changes in MTL function. We collected functional magnetic resonance imaging data during an incidental encoding task in 80 participants, divided equally across four age groups: 8-year-olds, 10- to 11-year-olds, 14-year-olds, and young adults. Developmental differences in MTL activation profiles were observed. Fourteen-year-olds and adults engaged regions of the hippocampus and posterior parahippocampal gyrus selectively for subsequent detail recollection, whereas 8- and 10- to 11-year-olds did not. In 8-year-olds, these regions were recruited indiscriminately for detail recollection and item recognition; in 10- to 11-year-olds, activation in these regions did not consistently predict subsequent memory. These results suggest there are changes in the functional organization of the MTL, such that the hippocampus and posterior parahippocampal gyrus become increasingly specialized for recollection; these changes may be in part responsible for long-term memory improvements during childhood.

Vivid memory for an episode generally includes memory for a central object or event plus memory for background context or source information. To assess neural differences between source and item memory, we used event-related potentials (ERPs) to monitor relevant memory processes at both encoding and retrieval. Participants fluent in Chinese studied Chinese words superimposed on a square or circular background during the study phase, followed by a 1-min delay. Then, memory was tested for both the words (items) and the corresponding background (source), or, in other blocks, tested for the words alone. ERPs to study-phase words differed as a function of whether the word was later remembered. These Dm effects in the interval from 400 to 600 ms, however, did not differ according to whether or not source was remembered. In contrast, ERPs to test-phase words showed clear old/new effects that did differ across conditions. When both item and source were remembered accurately, old/new effects emerged earlier and were larger in amplitude than when source memory was either incorrect or not queried. These results demonstrate that encoding processes indexed by ERPs may have primarily reflected encoding of the visual and semantic properties of these words, stressing item memory over source memory. Retrieval processes indexed by ERPs, in contrast, likely reflected a combination of item retrieval, source retrieval, and related processing engaged when people were remembering words seen earlier.

Children with cerebral palsy (CP) often develop reduced passive range of motion with age. The determining factor underlying this process is believed to be progressive development of contracture in skeletal muscle that likely changes the biomechanics of the joints. Consequently, to identify the underlying mechanisms, we modeled the mechanical characteristics of the forearm flexors acting across the wrist joint. We investigated skeletal muscle strength (Grippit03) and passive stiffness and viscosity of the forearm flexors in 15 typically developing (TD) children (10 boys/5 girls, mean age 12 years, range 8–18 yrs) and nine children with CP Nine children (6 boys/3 girls, mean age 11 ± 3 years (yrs), range 7–15 yrs) using the NeuroFlexor03 apparatus. The muscle stiffness we estimate and report is the instantaneous mechanical response of the tissue that is independent of reflex activity. Furthermore, we assessed cross-sectional area of the flexor carpi radialis (FCR) muscle using ultrasound. Age and body weight did not differ significantly between the two groups. Children with CP had a significantly weaker (6165%,p< 0.01) grip and had smaller cross-sectional area (6143%,p< 0.01) of the FCR muscle. Passive stiffness of the forearm muscles in children with CP was increased 2-fold (p< 0.05) whereas viscosity did not differ significantly between CP and TD children. FCR cross-sectional area correlated to age (R2= 0.58,p< 0.01), body weight (R2= 0.92,p< 0.0001) and grip strength (R2= 0.82,p< 0.0001) in TD children but only to grip strength (R2= 0.60,p< 0.05) in children with CP. We conclude that children with CP have weaker, thinner, and stiffer forearm flexors as compared to typically developing children.

Abstract Objective: The aim of the current study was to investigate the impact of gender and age on incidental and intentional memory in healthy participants and to explore the strength of the association of incidental and intentional memory with attentional and executive functioning. Method: A total number of 47 participants underwent a driving simulation experiment and went through detailed neuropsychological testing. Incidental memory was assessed with a questionnaire that evaluated the memorization of information related to the driving simulator task while intentional memory was assessed using the Hopkins Verbal Learning Test-Revised and the Brief Visuospatial Memory Test-Revised. Results: The analysis revealed a greater impact of age on incidental as compared to intentional memory. Gender did not appear to have such an effect on either incidental or intentional memory. Finally, attentional and executive functioning were more strongly associated with incidental memory than the intentional memory measures that were utilized in the current study. Conclusions: Ageing appears to affect incidental rather than intentional memory to a greater extent. In addition, attentional and executive functioning seem to play a more important role in incidental than intentional encoding and consolidation processes.

In the adult literature, emotional arousal is regarded as a source of the enhancing effect of emotion on subsequent memory. Here, we used behavioral and electrophysiological methods to examine the role of emotional arousal on subsequent memory in school-age children. Furthermore, we implemented a reappraisal instruction to manipulate (down-regulate) emotional arousal at encoding to examine the relation between emotional arousal and subsequent memory. Participants (8-year-old girls) viewed emotional scenes as electrophysiological (EEG) data were recorded and participated in a memory task 1 to 5days later where EEG and behavioral responses were recorded; participants provided subjective ratings of the scenes after the memory task. The reappraisal instruction successfully reduced emotional arousal responses to negative stimuli but not positive stimuli. Similarly, recognition performance in both event-related potentials (ERPs) and behavior was impaired for reappraised negative stimuli but not positive stimuli. The findings indicate that ERPs are sensitive to the reappraisal of negative stimuli in children as young as 8years. Furthermore, the findings suggest an interaction of emotion and memory during the school years, implicating the explanatory role of emotional arousal at encoding on subsequent memory performance in female children as young as 8years.

Abstract Leading theories propose that when remembering past events, medial temporal lobe (MTL) structures reinstate the neural patterns that were active when those events were initially encoded. Accurate reinstatement is hypothesized to support detailed recollection of memories, including their source. While several studies have linked cortical reinstatement to successful retrieval, indexing reinstatement within the MTL network and its relationship to memory performance has proved challenging. Here, we addressed this gap in knowledge by having participants perform an incidental encoding task, during which they visualized people, places, and objects in response to adjective cues. During a surprise memory test, participants saw studied and novel adjectives and indicated the imagery task they performed for each adjective. A multivariate pattern classifier was trained to discriminate the imagery tasks based on functional magnetic resonance imaging (fMRI) responses from hippocampus and MTL cortex at encoding. The classifier was then tested on MTL patterns during the source memory task. We found that MTL encoding patterns were reinstated during successful source retrieval. Moreover, when participants made source misattributions, errors were predicted by reinstatement of incorrect source content in MTL cortex. We further observed a gradient of content-specific reinstatement along the anterior-posterior axis of hippocampus and MTL cortex. Within anterior hippocampus, we found that reinstatement of person content was related to source memory accuracy, whereas reinstatement of place information across the entire hippocampal axis predicted correct source judgments. Content-specific reinstatement was also graded across MTL cortex, with PRc patterns evincing reactivation of people and more posterior regions, including PHc, showing evidence for reinstatement of places and objects. Collectively, these findings provide key evidence that source recollection relies on reinstatement of past experience within the MTL network. Copyright 2016 Elsevier Ltd. All rights reserved.

Retrieval practice enhances memory retention more than re-studying. The underlying mechanisms of this retrieval practice effect have remained widely unclear. According to the elaborative retrieval hypothesis, activation of elaborative information occurs to a larger extent during testing than re-studying. In contrast, the episodic context account has suggested that recollecting prior episodic information (especially the temporal context) contributes to memory retention. To adjudicate the distinction between these two accounts, the present study used the classical retrieval practice effect paradigm to compare retrieval practice and elaborative study. In an initial behavioral experiment, retrieval practice produced greater retention than elaboration and re-studying in a one-week delayed test. In a subsequent event-related potential (ERP) experiment, retrieval practice resulted in reliably superior accuracy in the delayed test compared to elaborative study. In the ERPs, a frontally distributed subsequent memory effect (SME), starting at 300 ms, occurred in the elaborative study condition, but not in the retrieval practice condition. A parietal SME emerged in the retrieval practice condition from 500 to 700 ms, but was absent in the elaborative study condition. After 700 ms, a late SME was present in the retrieval practice condition, but not in the elaborative study condition. Moreover, SMEs lasted longer in retrieval practice than in elaboration. The frontal SME in the elaborative study condition might be related to semantic processing or working memory-based elaboration, whereas the parietal and widespread SME in the retrieval practice condition might be associated with episodic recollection processes. These findings contradict the elaborative retrieval theory, and suggest that contextual recollection rather than activation of semantic information contributes to the retrieval practice effect, supporting the episodic context account.

Healthy aging is associated with declines in episodic memory. This reduction is thought to be due in part to age-related differences in encoding-related processes. In the current study, we performed an activation likelihood estimation meta-analysis of functional magnetic resonance imaging (fMRI) studies assessing age-related differences in the neural correlates of episodic encoding. Only studies using the subsequent memory paradigm were included. We found age-related under-recruitment of occipital and fusiform cortex, but over-recruitment in a set of regions including bilateral middle/superior frontal gyri, anterior medial frontal gyrus, precuneus and left inferior parietal lobe. We demonstrate that all of the regions consistently over-recruited by older adults during successful encoding exhibit either direct overlap, or occur in close vicinity to regions consistently involved in unsuccessful encoding in young adults. We discuss the possibility that this overall pattern of age-related differences represents an age-related shift in focus: away from perceptual details, and toward evaluative and personal thoughts and feelings during memory tasks. We discuss whether these age-related differences in brain activation benefit performance in older adults, and additional considerations.

We investigated the role of distinct regions of the default-mode network (DMN) during memory encoding with fMRI. Subjects encoded words using either a strategy that emphasized self-referential (pleasantness) processing, or one that emphasized semantic (man-made/natural) processing. During encoding subjects were intermittently presented with thought probes to evaluate if they were concentrated and on-task or exhibiting task-unrelated thoughts (TUT). After the scanning session subjects performed a source retrieval task to determine which of two judgments they performed for each word at encoding. Source retrieval accuracy was higher for words encoded with the pleasantness vs. the man-made/natural task and there was a trend for higher performance for words preceding on-task vs. TUT reports. fMRI results show that left anterior medial PFC and left angular gyrus activity was greater during successful vs. unsuccessful encoding during both encoding tasks. Greater activity in left anterior cingulate and bilateral lateral temporal cortex was related successful vs. unsuccessful encoding only in the pleasantness task. In contrast, posterior cingulate, right anterior cingulate and right temporoparietal junction were activated to a greater extent in unsuccessful vs. successful encoding across tasks. Finally, activation in posterior cingulate and bilateral dorsolateral prefrontal cortex was related to TUT across tasks; moreover, we observed a conjunction in posterior cingulate between encoding failure and TUT. We conclude that DMN regions play dissociable roles during memory formation, and that their association with subsequent memory may depend on the manner in which information is encoded and retrieved.

In a recent empirical study, Starns, Hicks, Brown, and Martin ( Memory & Cognition , 36, 1–8 2008 ) collected source judgments for old items that participants had claimed to be new and found residual source discriminability depending on the old-new response bias. The authors interpreted their finding as evidence in favor of the bivariate signal-detection model, but against the two-high-threshold model of item/source memory. According to the latter, new responses only follow from the state of old-new uncertainty for which no source discrimination is possible, and the probability of entering this state is independent of the old-new response bias. However, when missed old items were presented for source discrimination, the participants could infer that the items had been previously studied. To test whether this implicit feedback led to second retrieval attempts and thus to source memory for presumably unrecognized items, we replicated Starns et al.’s ( Memory & Cognition , 36, 1–8 2008 ) finding and compared their procedure to a procedure without such feedback. Our results challenge the conclusion to abandon discrete processing in source memory; source memory for unrecognized items is probably an artifact of the procedure, by which implicit feedback prompts participants to reconsider their recognition judgment when asked to rate the source of old items in the absence of item memory.

The aim of this study was to investigate whether the recognition of faces with neutral expressions differs when they are encoded under different emotional contexts (positive, negative or non-emotional). The effects of the emotional valence context on the subsequent memory effect (SME) and the autonomic responses were also examined. Twenty-eight participants performed a betting-game task in which the faces of their virtual opponents were presented in each trial. The probability of winning or losing was manipulated to generate positive or negative contexts, respectively. Additionally, the participants performed the same task without betting as a non-emotional condition. After the encoding phase, an old/new paradigm was performed for the faces of the virtual opponents. The recognition was superior for the faces encoded in the positive contexts than for the faces encoded in the non-emotional contexts. The skin conductance response amplitude was equivalent for both of the emotional contexts. The N170 and P300 components at occipital sites and the frontal slow wave manifested SMEs that were modulated by positive contexts; neither negative nor non-emotional contexts influenced these effects. The behavioral and neurophysiological data demonstrated that positive contexts are stronger predictors of episodic memory than negative or non-emotional contexts.

Abstract Although studies in animals and patients have demonstrated that brain oscillations play a role in declarative memory encoding and retrieval, little has been done to investigate the temporal dynamics and sources of brain activity in healthy human subjects performing such tasks. In a magnetoencephalography study using pictorial stimuli, we have now identified oscillatory activity in the gamma (60-90 Hz) and theta (4.5-8.5 Hz) band during declarative memory operations in healthy participants. Both theta and gamma activity was stronger for the later remembered compared with the later forgotten items (the "subsequent memory effect"). In the retrieval session, theta and gamma activity was stronger for recognized items compared with correctly rejected new items (the "old/new effect"). The gamma activity was also stronger for recognized compared with forgotten old items (the "recognition effect"). The effects in the theta band were observed over right parietotemporal areas, whereas the sources of the effects in the gamma band were identified in Brodmann area 18/19. We propose that the theta activity is directly engaged in mnemonic operations. The increase in neuronal synchronization in the gamma band in occipital areas may result in a stronger drive to subsequent areas, thus facilitating both memory encoding and retrieval. Alternatively, the gamma synchronization might reflect representations being reinforced by top-down activity from higher-level memory areas. Our results provide additional insight on human declarative memory operations and oscillatory brain activity that complements previous electrophysiological and brain imaging studies.

Event-related brain potentials (ERPs) were recorded during an incidental learning paradigm. Recall and recognition were better for words initially presented in tasks requiring semantic decisions (i.e., ‘is it living?’ or ‘is it edible?’) than for words in tasks requiring non-semantic decisions. ERPs elicited during performance of these tasks were predictive of subsequent memory performance. A late positive ERP elicited by words later recalled or recognized was larger than that elicited by words later forgotten. This enhanced positivity for to-be-remembered words could be accounted for, in part, by the fact that words in semantic tasks were remembered better and elicited larger ERPs than did words in non-semantic tasks. Similarly, words followed by affirmative rather than negative decisions were associated both with better recognition and with larger ERPs. However, ERPs were sensitive to processes that influenced later memory performance even within an individual semantic task and within the affirmative decision condition. In addition, results showed that the ERP differences base on later memory performance did not necessarily arise from amplitude variation in P3 waves that occurred at the same time.

The present study investigated whether the neural correlates of source memory vary according to study task. Subjects studied visually presented words in one of two background contexts. In each test, subjects made old/new recognition and source memory judgments. In one study test cycle, study words were subjected to animacy judgments, whereas in another cycle the study task required syllable judgments. Functional magnetic resonance imaging (fMRI) was employed to contrast the neural activity elicited by study words that attracted accurate source judgments on the later memory test, as opposed to words for which source judgments were incorrect or for which source information was unavailable. In both tasks, relative to words for which source memory failed, study words that were later assigned to the correct source elicited enhanced activity in ventral extrastriate cortex. In addition to these common effects of subsequent source memory, additional effects were observed that were selective for each study task. The present findings add weight to the proposal that neural activity supporting successful episodic memory encoding is a reflection of both the online processing engaged by an episode as it is experienced, and the demands imposed by the later retrieval task.

Overall, these results suggest that face recognition is modulated by top-down influences from brain areas associated with emotional memory, enhancing encoding and retrieval in particular for fearful emotional expressions.

The aim of the present study was to investigate developmental changes in encoding processes between 6-year-old children and adults using event-related potentials (ERPs). Although episodic memory (090004EM090005) effects have been reported in both children and adults at retrieval and subsequent memory effects have been established in adults, no previous ERP studies have examined subsequent memory effects in children. This represents a critical gap in the literature because encoding processes, and changes in neural correlates supporting encoding, partially account for age-related improvements in children's memory performance. Results revealed that subsequent memory effects differed between children and adults temporally, directionally, and topographically. These findings lend support to the hypothesis that encoding processes and their neural correlates are an important source of change in memory development.A video abstract of this article can be viewed at http://youtu.be/sH83_qVimgc.

Abstract The ability to mentally re-experience past events improves significantly from childhood to young adulthood; however, the mechanisms underlying this ability remain poorly understood, partially because different tasks are used across the lifespan. This study was designed to address this gap by assessing the development of event-related potential (ERP) correlates associated with subjective indices of recollection. Children, adolescents, and adults performed Tulving's () remember/know paradigm while ERPs were recorded during memory encoding (Experiment 1) and retrieval (Experiment 2). Behaviorally, children recognized fewer items than adolescents and adults. All age groups reliably made subjective judgments of recollection, although the ability to make these judgments improved with age. At encoding, the ERP effect associated with recollection was present and comparable across age groups. In contrast, the ERP effect associated with recollection at retrieval differed as a function of age group; specifically, this effect was absent in children, topographically widespread in adolescents, and, consistent with previous literature, maximal over left centro-parietal leads in adults. These findings suggest that encoding processes associated with the subsequent subjective experience of recollection may be similar among children, adolescents, and adults and that age-related improvement in recollection may be primarily attributable to the development of processes that follow the initial encoding of stimuli (i.e., consolidation, storage, retrieval). 2017 John Wiley & Sons Ltd.

The electrocortical manifestations of levels of perceptual processing and memory performance were investigated by recording event related potentials (ERPs) during a verbal comparison task and a subsequent test of recognition memory. Two words were judged, on each trial, to be the same or different according to an orthographic, phonemic, or semantic criterion. Orthographic processing of words led to poor performance on a test of recognition memory whereas phonemic and semantic processing led to increasingly better performance. "Same" judgments led to better memory performance for phonemically and semantically processed items. The ERP waveforms included a late positive component (LPC) and a slow wave, both of which were responsive to the comparison criterion and the type of judgment. Further, the LPC appeared to index recognition accuracy in the memory test. The ERP data are interpreted as reflecting associative activation in the human memory system.

Abstract The structural and functional brain circuitries supporting episodic memory undergo profound reorganization in childhood and old age. We propose a two-component framework that combines and integrates evidence from child development and aging. It posits that episodic memory builds on two interacting components: (a) the strategic component, which refers to memory control operations, and (b) the associative component, which refers to mechanisms that bind different features of a memory episode into a compound representation. We hypothesize that: (a) children's difficulties in episodic memory primarily originate from low levels of strategic operations, and reflect the protracted development of the prefrontal cortex (PFC); (b) deficits in episodic memory performance among older adults originate from impairments in both strategic and associative components, reflecting senescent changes in the PFC and the medio-temporal lobes (MTL). Initial behavioral and neural evidence is consistent with both hypotheses. The two-component framework highlights the specificities of episodic memory in different age periods, helps to identify and dissociate its components, and contributes to understanding the interplay among maturation, learning, and senescence. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Abstract Primate cognition requires interaction processing. Interactions can reveal otherwise hidden properties of intentional agents, such as thoughts and feelings, and of inanimate objects, such as mass and material. Where and how interaction analyses are implemented in the brain is unknown. Using whole-brain functional magnetic resonance imaging in macaque monkeys, we discovered a network centered in the medial and ventrolateral prefrontal cortex that is exclusively engaged in social interaction analysis. Exclusivity of specialization was found for no other function anywhere in the brain. Two additional networks, a parieto-premotor and a temporal one, exhibited both social and physical interaction preference, which, in the temporal lobe, mapped onto a fine-grain pattern of object, body, and face selectivity. Extent and location of a dedicated system for social interaction analysis suggest that this function is an evolutionary forerunner of human mind-reading capabilities. Copyright 2017, American Association for the Advancement of Science.

How do people consider other minds during cooperation versus competition? Some accounts predict that theory of mind (ToM) is recruited more for cooperation versus competition or competition versus cooperation, whereas other accounts predict similar recruitment across these two contexts. The present fMRI study examined activity in brain regions for ToM (bilateral temporoparietal junction, precuneus, dorsomedial prefrontal cortex) across cooperative and competitive interactions with the same individual within the same paradigm. Although univariate analyses revealed that ToM regions overall were recruited similarly across interaction contexts, multivariate pattern analyses revealed that these regions nevertheless encoded information separating cooperation from competition. Specifically, ToM regions encoded differences between cooperation and competition when people believed the outcome was determined by their and their partner's choices but not when the computer determined the outcome. We propose that, when people are motivated to consider others' mental states, ToM regions encode different aspects of mental states during cooperation versus competition. Given the role of these regions for ToM, these findings reveal distinct patterns of social cognition for distinct motivational contexts.

Contemporary memory theories often distinguish between contextual recollection and acontextual familiarity as two fundamentally different types of recognition memory. It is currently unclear whether recollection and familiarity are supported by two correspondingly distinct retrieval mechanisms, or whether the same type of retrieval processing supports both phenomena. Electrophysiological findings in humans have widely been cited as support for the former, two-process position, in that late-onset parietal “LPC” potentials have been linked to recollection and earlier frontal “FN400” potentials to familiarity. However, recognition memory is generally studied using conceptually rich stimuli such as words, which leaves open an alternative interpretation that one or both of these electrophysiological signals reflect conceptual processing distinct from recollection and familiarity per se. We tested this hypothesis using conceptually impoverished kaleidoscope images, such that opportunities for conceptual processing were minimized. Recollection-based and familiarity-based recognition in a remember/know paradigm were both indexed by LPC potentials. Old/new amplitude differences were greater for recollection compared to familiarity. Despite ample familiarity-based recognition, FN400 old/new effects were not observed, consistent with the contention that these potentials index conceptual processing rather than familiarity. These results cast doubt on interpretations of prior electrophysiological evidence obtained using conceptually rich stimuli as dissociating neural mechanisms of recollection and familiarity. We also found that neural events during encoding differentially predicted later recollection versus later familiarity. Collectively, these findings suggest that the engagement of distinct encoding processes can preferentially lead to recollection or to familiarity even if one type of retrieval process is responsible for both memory expressions.

To understand human memory, it is important to determine why some experiences are remembered whereas others are forgotten. Until recently, insights into the neural bases of human memory encoding, the processes by which information is transformed into an enduring memory trace, have primarily been derived from neuropsychological studies of humans with select brain lesions. The advent of functional neuroimaging methods, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), has provided a new opportunity to gain additional understanding of how the brain supports memory formation. Importantly, the recent development of event-related fMRI methods now allows for examination of trial-by-trial differences in neural activity during encoding and of the consequences of these differences for later remembering. In this review, we consider the contributions of PET and fMRI studies to the understanding of memory encoding, placing a particular emphasis on recent event-related fMRI studies of the Dm effect: that is, differences in neural activity during encoding that are related to differences in subsequent memory. We then turn our attention to the rich literature on the Dm effect that has emerged from studies using event-related potentials (ERPs). It is hoped that the integration of findings from ERP studies, which offer higher temporal resolution, with those from event-related fMRI studies, which offer higher spatial resolution, will shed new light on when and why encoding yields subsequent remembering.

In this study, we report evidence that neural activity reflecting the encoding of emotionally neutral information in memory is reduced when neutral and emotional stimuli are intermixed during encoding. Specifically, participants studied emotional and neutral pictures organized in mixed lists (in which emotional and neutral pictures were intermixed) or in pure lists (only‐neutral or only‐emotional pictures) and performed a recall test. To estimate encoding efficiency, we used the Dm effect, measured with event‐related potentials. Recall for neutral items was lower in mixed compared to pure lists and posterior Dm activity for neutral items was reduced in mixed lists, whereas it remained robust in pure lists. These findings might be caused by an asymmetrical competition for attentional and working memory resources between emotional and neutral information, which could be a major determinant of emotional memory effects.

fMRI was employed to investigate the role of the left inferior frontal gyrus (LIFG) in the encoding of item-item and item-context associations. On each of a series of study trials subjects viewed a picture that was presented either to the left or right of fixation, along with a subsequently presented word that appeared at fixation. Memory was tested in a subsequent memory test that took place outside of the scanner. On each test trial one of two forced choice judgments was required. For the associative test, subjects chose between the word paired with the picture at study and a word studied on a different trial. For the source test, the judgment was whether the picture had been presented on the left or right. Successful encoding of associative information was accompanied by subsequent memory effects in several cortical regions, including much of the LIFG. By contrast, successful source encoding was selectively associated with a subsequent memory effect in right fusiform cortex. The finding that the LIFG was enhanced during successful associative, but not source, encoding is interpreted in light of the proposal that subsequent memory effects are localized to cortical regions engaged by the on-line demands of the study task.

Social relevance has an enhancing effect on learning and subsequent memory retrieval. The ability to learn from and remember social interactions may impact on susceptibility to financial exploitation, which is elevated in individuals with dementia. The current study aimed to investigate learning and memory of social interactions, the relationship between performance and financial vulnerability and the neural substrates underpinning performance in 14 Alzheimer's disease (AD) and 20 behavioural-variant frontotemporal dementia (bvFTD) patients and 20 age-matched healthy controls. On a “trust game” task, participants invested virtual money with counterparts who acted either in a trustworthy or untrustworthy manner over repeated interactions. A non-social “lottery” condition was also included. Participants’ learning of trust/distrust responses and subsequent memory for the counterparts and nature of the interactions was assessed. Carer-rated profiles of financial vulnerability were also collected. Relative to controls, both patient groups showed attenuated learning of trust/distrust responses, and lower overall memory for social interactions. Despite poor learning performance, both AD and bvFTD patients showed better memory of social compared to non-social interactions. Importantly, better memory for social interactions was associated with lower financial vulnerability in AD, but not bvFTD. Learning and memory of social interactions was associated with medial temporal and temporoparietal atrophy in AD, whereas a wider network of frontostriatal, insular, fusiform and medial temporal regions was implicated in bvFTD. Our findings suggest that although social relevance influences memory to an extent in both AD and bvFTD, this is associated with vulnerability to financial exploitation in AD only, and is underpinned by changes to different neural substrates. Theoretically, these findings provide novel insights into potential mechanisms that give rise to vulnerability in people with dementia, and open avenues for possible interventions.

It is well accepted that recognition memory reflects the contribution of two separable memory retrieval processes, namely recollection and familiarity. However, fundamental questions remain regarding the functional nature and neural substrates of these processes. In this article, we describe a simple quantitative model of recognition memory (i.e., the dual-process signal detection model) that has been useful in integrating findings from a broad range of cognitive studies, and that is now being applied in a growing number of neuroscientific investigations of memory. The model makes several strong assumptions about the behavioral nature and neural substrates of recollection and familiarity. A review of the literature indicates that these assumptions are generally well supported, but that there are clear boundary conditions in which these assumptions break down. We argue that these findings provide important insights into the operation of the processes underlying recognition. Finally, we consider how the dual-process approach relates to recent neuroanatomical and computational models and how it might be integrated with recent findings concerning the role of medial temporal lobe regions in other cognitive functions such as novelty detection, perception, implicit memory and short-term memory. 2010 Wiley-Liss, Inc.