Journal of Cognitive Neuroscience

Auditory working memory is often conceived of as a unitary capacity, with memory for different auditory materials (syllables, pitches, rhythms) thought to rely on similar neural mechanisms. One spontaneous behavior observed in working memory studies is chunking. For example, individuals often recount digit sequences in groups, or chunks, of 3 to 4 digits, and this chunking improves performance. Chunking may also operate in musical rhythm, with beats acting as chunk boundaries for tones in rhythmic sequences. Similar to chunking, beat-based structure in rhythms also improves performance. Thus, beat processing may rely on the same mechanisms that underlie chunking of verbal material. The current fMRI study examined whether beat perception is a type of chunking, measuring brain responses to chunked and unchunked letter sequences relative to beat-based and nonbeat-based rhythmic sequences. Participants completed a sequence discrimination task, and comparisons between stimulus encoding, maintenance, and discrimination were made for both rhythmic and verbal sequences. Overall, rhythm and verbal working memory networks overlapped substantially. When comparing rhythmic and verbal conditions, rhythms activated basal ganglia, supplementary motor area, and anterior insula, compared to letter strings, during encoding and discrimination. Letter strings compared to rhythms activated bilateral auditory cortex during encoding, and parietal cortex, precuneus, and middle frontal gyri during discrimination. Importantly, there was a significant interaction in the basal ganglia during encoding: activation for beat-based rhythms was greater than for nonbeat-based rhythms, but verbal chunked and unchunked conditions did not differ. The significant interaction indicates that beat perception is not simply a case of chunking, suggesting a dissociation between beat processing and grouping mechanisms that warrants further exploration.

A narrative is a coherent representation of actual or fictional events designed to connect experiences. Narratives provide a unique opportunity to investigate brain functions in scenarios more closely resembling real-world experiences. However, most neuroimaging studies examining narrative formation have utilized static stimuli that fail to capture the intricacies of narrative construction in everyday life, particularly how cognitive demands change over the course of narrative processing. The current research uses functional magnetic resonance imaging (fMRI) to examine dynamic narrative processing over the course of a full-length audiovisual narrative. We examined changes in neural synchrony (as quantified by intersubject correlations) in areas related to semantic memory, episodic memory, and visuospatial attention between the beginning, middle, and end of the narrative. Results from two experiments identified two core narrative processing networks responsible for constructing coherent representations across extended timescales. The first network is associated with the early narrative construction, and includes the right intraparietal sulcus/superior parietal lobule, bilateral angular gyrus, bilateral precuneus, and left fusiform gyrus. The second network consists of the right ventral frontal cortex and bilateral parahippocampal cortices, and is associated with longer term narrative integration. Together, these regions provide the framework for successful narrative processing during naturalistic stimuli.

Listening to music during cognitive activities, such as reading and studying, is very common in human daily life. Therefore, it is important to understand how music interacts with concurrent cognitive functions, particularly memory. Current literature has presented mixed results for whether music can benefit learning in other modalities. Evidence is needed for what neural mechanisms music can tap into to enhance concurrent memory processing. This fMRI study aimed to begin filling this gap by investigating how music of varying predictability levels influences parallel visual sequence encoding performance. Behavioral results suggest that overall, predictable music enhances visual sequential encoding, and this effect increases with the structural regularity and familiarity of music. fMRI results indicate that during visual sequence encoding, music activates traditional music-processing and motor-related areas, but decreases parahippocampal and striatal engagement. This deactivation may indicate a more efficient encoding of visual information when music is present. By comparing music conditions of different structural predictability and familiarity, we probed how this occurs. We demonstrate improved encoding with increased syntactical regularity, which was associated with decreased activity in default mode network and increased activity in inferior temporal gyrus. Furthermore, the temporal schema provided by music familiarity may influence encoding through altered functional connectivity between the prefrontal cortex, medial temporal lobe and striatum. Overall, we propose that pairing music with learning might facilitate memory by reducing neural demands for visual encoding and simultaneously strengthening the connectivity between the medial temporal lobe and frontostriatal loops important for sequencing information. Significance StatementThere is considerable interest in what mechanisms can be tapped to improve human memory. Music provides a potential modulator, but few studies have investigated music effects on encoding episodic memory. This study used a novel design to examine how music can influence concurrent visual item sequence encoding. We provided neural data to better understand mechanisms behind potential benefits of music for learning. Our results demonstrated predictable music may help guide parallel learning of sequences in another modality. We found that music might facilitate processing in neural systems associated with visual declarative long-term and working memory, and familiar music might modulate reward circuits and provide a temporal schema which facilitates better encoding of the temporal structure of new non-music information.

Although in many cases salient stimuli capture attention involuntarily, it has been proposed recently that under certain conditions the bottom-up signal generated by such stimuli can be proactively suppressed. In support of this signal suppression hypothesis, ERP studies have demonstrated that salient stimuli that do not capture attention elicit a distractor positivity (PD), a putative neural index of suppression. At the same time, it is becoming increasingly clear that regularities across preceding search episodes have a large influence on attentional selection. Yet to date, studies in support of the signal suppression hypothesis have largely ignored the role of selection history on the processing of distractors. The current study addressed this issue by examining how electrophysiological markers of attentional selection (N2pc) and suppression (PD) elicited by targets and distractors respectively were modulated when the search target randomly varied instead of being fixed across trials. Results showed that while target selection was unaffected by this manipulation, both in terms of manual response times, as well as in terms of the N2pc component, the PD component was reliably attenuated when the target features varied randomly across trials. This result demonstrates that the distractor PD, which is typically considered the marker of selective distractor processing cannot unequivocally be attributed to suppression only, as it also, at least in part, reflects the upweighting of target features.

Over time, we develop event schemas or scripts that shape our expectations about what typically happens in certain contexts. However, even after forming a memory about a certain event, we are often exposed to related information about that same event at later points in time. This additional information sometimes causes one to have to re-evaluate the interpretation of the original event. Over a two-day fNIRS experiment, participants were exposed to events that were subsequently updated with schema-congruent or schemaincongruent additional details. These schema-incongruent additional details make those events more fitting to another schema than originally was the case, meaning that participants would need to dissociate that event from the original schema and re-integrate it with another schema. The fNIRS results showed stronger PFC activity for events updated with schema-congruent compared to schema-incongruent details. When specifically looking at those events that were updated with schema-incongruent details, our results suggest that dissociating an event from the original schema and re-integrating it with another schema was accompanied by an initial PFC decrease early in the trial followed by a PFC increase later in the trial. This was a distinctly different pattern compared to trials in which participants failed to re-integrate the event with another schema, which showed delayed PFC increase with lower amplitude and no initial PFC decrease. Our results refine our understanding of mechanisms of adaptive memory updating in the face of conflicting information.

Our memories do not simply keep time -- they warp it, bending the past to fit the structure of our experiences. For example, people tend to remember items as occurring farther apart in time if they spanned a change in context, or event boundary, compared to the same context. While these distortions could sacrifice precise timing, they might also serve to divide and organize information into distinct memories. In the current study, we combined functional magnetic resonance imaging (fMRI; n = 32) with eye-tracking (n = 28) to test whether activation of the dopaminergic system, known to influence encoding and time perception, predicts time dilation between adjacent events in memory. Participants encoded item sequences while listening to tones that mostly repeated over time, forming a stable auditory context, but occasionally switched, creating an event boundary. We found that boundaries predicted greater retrospective estimates of time between item pairs. Critically, tone switches significantly activated the ventral tegmental area (VTA), a key midbrain dopaminergic region, and these responses predicted greater time dilation between item pairs that spanned those switches. Boundaries furthermore predicted a momentary increase in blinks. Activation of the VTA predicted blinking in general, consistent with the idea that blink behavior is a potential marker of dopaminergic activity. On a larger timescale, higher blink counts predicted greater time dilation in memory, but only for boundary-spanning item pairs. Together, these findings suggest that dopaminergic processes are sensitive to event structure and may drive temporal distortions that help to separate memories of distinct events.

Default mode network (DMN) activity, measured with fMRI, typically increases during internally directed thought, and decreases during tasks that demand externally focused attention. However, Crittenden et al. (2015) and Smith et al. (2018) reported increased DMN activity during demanding external task switches between different cognitive domains, compared to within-domain switches and task repeats. This finding is hard to reconcile with many dominant views of DMN function. Here, we aimed to replicate this DMN task-switch effect in a similar paradigm and test whether it reflects increased representation of broader context, specifically of a scene presented behind the focal task. In Core DMN, we found significant activity for all task switches, compared to task repeats, and stronger activity for switches between rest and task. Although the content of the background scene was attended, recalled, and neurally decodable, there was no evidence that this differed by switch type. Therefore, external task switches activated DMN without enhanced processing of the surrounding scene. Surprisingly, DMN activity at within-domain switches was no less than at between-domain switches. We suggest that modulation of DMN activity by task switches reflects a shift in the current cognitive model and depends on the overall complexity of that model.

People often want to recall only currently relevant events, but this selective remembering is not always possible. We contrasted two candidate mechanisms: the overlap between retrieval cues and stored memory traces, and the ease of recollection. In two preregistered experiments (Ns = 28) we used event-related potentials (ERPs) to quantify pre-retrieval selection and the goal states - retrieval orientations - thought to achieve this selection. Participants viewed object pictures or heard object names, and one of these sources was designated as targets in each memory test. We manipulated cue overlap by probing memory with visual names (Experiment 1) or line drawings (Experiment 2). Results revealed that regardless of which source was targeted, the left parietal ERP effect indexing recollection was selective when test cues overlapped more with the targeted than non-targeted information, despite consistently better memory for pictures. ERPs for unstudied items were also more positive-going when cue overlap was high, suggesting that engagement of retrieval orientations reflected availability of external cues matching the targeted source. The data support the view that selection can act prior to recollection if there is sufficient overlap between retrieval cues and targeted versus competing memory traces.

Our goals are achieved through extended task episodes. While its well recognized that such episodes are controlled and executed as a single unit, how this is achieved remains unclear. Key observations during the execution of extended episodes - increased reaction time at episode beginnings and widespread neural activation at episode completions - have suggested that some additional, episode-related goings-on may occur at the beginning and the end. We found that when participants executed episodes of different durations, but involving trials identical in every aspect, distinct episodes elicited distinct activity patterns across the entire cortex at their beginnings as well as at their completions, showing that information related to the overarching episode floods the cortex at these junctures and evidencing a program related to the entire episode that got instated and dismantled when episodes begin and complete. This episode-related program was distinct from rules, contexts, working memory contents, and representations of identity and position of steps - issues well recognized to have a role in task execution and known to elicit distinct activity patterns in frontoparietal regions that typically activate during task execution. Unlike these issues, this program was discernible not only in frontoparietal regions but across the entire cortex, regardless of the level of univariate activation exhibited by that region, indicating that the dynamics of this program involved a massive resetting of neural activity across the entire cortex.

Prior studies examining the neural mechanisms underlying retrieval success and precision have yielded inconsistent results. Here, their neural correlates were examined using a memory task that assessed precision for spatial location. A sample of healthy young adults underwent fMRI scanning during a single study-test cycle. At study, participants viewed a series of object images, each placed at a randomly selected location on an imaginary circle. At test, studied images were intermixed with new images and presented to the participants. The requirement was to move a cursor to the location of the studied image, guessing if necessary. Participants then signaled whether the presented image as having been studied. Memory precision was quantified as the angle between the studied location and the location selected by the participant. A precision effect was evident in the left angular gyrus, where BOLD activity covaried across trials with location accuracy. Multi-voxel pattern analysis also revealed a significant item-level reinstatement effect for high-precision trials. There was no evidence of a retrieval success effect in the angular gyrus. BOLD activity in the hippocampus was insensitive to both success and precision. These findings are partially consistent with prior evidence that success and precision are dissociable features of memory retrieval.

Humans complete different types of sequences as a part of everyday life. These sequences can be divided into two important categories: those that are abstract, in which the steps unfold according to a rule at super-second to minute time scale, and those that are motor, defined solely by individual movements and their order which unfold at the sub-second to second timescale. For example, the sequence of making spaghetti consists of abstract tasks (preparing the sauce and cooking the noodles) and nested motor actions (stir pasta water). Previous work shows neural activity increases (ramps) in the rostrolateral prefrontal (RLPFC) during abstract sequence execution (Desrochers et al., 2015, 2019). During motor sequence production, activity occurs in regions of the prefrontal cortex (Yewbrey et al., 2023). However, it remains unknown if ramping is a signature of motor sequence production as well or solely an attribute of abstract sequence monitoring and execution. We tested the hypothesis that significant ramping activity occurs during motor sequence production in the RLPFC. Contrary to our hypothesis, we did not observe significant ramping activity in the RLPFC during motor sequence production, but we found significant ramping activity in bilateral inferior parietal cortex, in regions distinct from those observed during an abstract sequence task. Our results suggest different prefrontal-parietal circuitry may underlie abstract versus motor sequence execution.

Episodic memories are not static but can be modified on the basis of new experiences, potentially allowing us to make valid predictions in the face of an ever-changing environment. Recent research has identified prediction errors during retrieval as a possible trigger for such changes. In the present study, we used modified episodic cues to investigate whether different types of mnemonic prediction errors modulate brain activity and subsequent memory performance. Participants encoded different episodes which consisted of short toy stories. During a subsequent functional magnetic resonance imaging (fMRI) session, participants were then presented videos showing the original episodes, or modified versions thereof. In modified videos, either the order of two subsequent action steps was changed or an object was exchanged for another. Content modifications recruited inferior frontal, parietal, and temporo-occipital areas reflecting the processing of the new object information, while brain responses to structure modifications in right dorsal premotor and inferior frontal areas remained subthreshold. In a post-fMRI memory test, the participants tendency to accept modified episodes as originally encoded increased significantly when they had been presented modified versions already during the fMRI session. Our study provides valuable initial insights into the neural processing of different types of episodic prediction errors and their influence on subsequent memory.

We make sense of everyday events by reasoning about their underlying causes. When we connect causal links between events separated in time, we often experience a sudden feeling of "aha!", or a moment of insight. What cognitive and neural processes underlie these moments of understanding? We hypothesized that narrative insight accompanies retrieving causally related past events in memory and updating the current event representation. To test this, we designed an fMRI study in which participants watched a TV episode that was cut into multiple events and presented in temporally scrambled orders. Participants pressed an "aha" button whenever they understood something new and verbally explained why they pressed in those moments at the end of each run. Supporting our prediction, more than 40% of insights included the retrieval of past events that were causally related to the current event. Neural patterns representing causally related past events were reinstated in cortical areas. This neural reinstatement drove sudden shifts in cortical representation patterns [~]2 s prior to aha button presses, reflecting an update in situational representation at moments of insight. Moreover, distributed areas in the brain represented causally related events with similar neural patterns, beyond their shared semantic or perceptual features. Together, the study suggests that we comprehend events by reinstating causally related past events via shared neural patterns, followed by updating neural patterns at moments of insight.

Keeping track of multiple moving objects across dynamic real-world scenarios such as driving, team sports, or crowded social environments is a fundamental challenge for visual attention. We have previously demonstrated that as the number of tracked objects increases, the strength of attentional facilitation allocated to each individual object decreases, limiting tracking success. It is also well established that beyond the number of tracked objects, faster-moving objects and objects embedded amongst higher numbers of distractors are more difficult to track. Are these effects on tracking difficulty also mediated by less effective allocation of attention to tracked targets as in the case of tracking more targets? If so, one should expect the strength of attentional modulation to drop systematically with increasing speed and total number of moving stimuli. In two experiments (total n = 70), participants were instructed to track moving targets amongst identical distractors while we manipulated object speed (Experiment 1) and number (Experiment 2). As expected, tracking performance declined with both manipulations. However, steady-state visual evoked potentials (SSVEPs) recorded during successful tracking revealed that attentional enhancement of tracked targets compared with distractors did not drop with increasing speed or object number. In summary, bottom-up changes in the stimulus display and top-down attentional manipulations affect tracking performance in independent ways, with the balance between strength of attentional allocation and bottom-up demands of the task determining successful tracking. The allocation of attention itself seems to be determined exclusively by top-down goals rather than being reactive to bottom-up display characteristics. Open Practices StatementParticipant level data and analysis code for all experiments are available at (https://osf.io/ypgfs/) and Experiment 1 was preregistered (https://osf.io/pxh25/). Significance statementKeeping track of multiple moving objects is fundamental to navigating dynamic real-world scenarios. This ability is accomplished through multifocal attentional selection, which weakens as the number of tracked targets increases. This study asks whether other stimulus manipulations increase tracking difficulty by diluting attentional allocation. Using steady-state visual evoked potentials to measure selective attention during tracking, we demonstrate that both increases in speed and distractor number impair performance, however, they do not affect attentional enhancement of targets. This suggests that top-down attentional control operates independently from bottom-up demands.

Evidence suggests that mental imagery and veridical perception recruit similar components of the human visual system. If so, neural representations of imagined and real stimuli should interact with one another, combining constructively or competing antagonistically. To determine if and how real and imagined visual stimuli interact in the brain, we asked participants to mentally visualise white bars at specific orientations after a rhythmic countdown while their brain activity was recorded using electroencephalography. Stimuli were imagined in isolation, or while another stimulus at a highly or poorly congruent orientation appeared on-screen. Multivariate pattern analysis was used to assess whether overlap between imagined and real stimulus features enhanced or diminished stimulus-specific sensory information in the brain. Findings showed that imagined and real orientation could be decoded from brain activity, with real orientation decoding mildly amplified by highly congruent, but not poorly congruent, imagined orientations. Although interactions between real and imagined stimuli were observed, no evidence was detected to suggest that imagined and real stimuli use the same neural activity patterns to encode sensory information. Instead, congruent imagery seemed only to amplify activity which had already been induced by real percepts, targeting late- but not early-stage perceptual representations. Ultimately, this study suggests that imagined and real stimuli interact in a mildly constructive manner, with imagination mostly acting in a modulatory capacity.

Recent prior work suggests a preferential relationship between working memory capacity (WMC) and proactive control, yet the neural mechanisms that support this relationship are still not well understood. We directly addressed this question by leveraging the Dual Mechanisms of Cognitive Control (DMCC) project, as it employed a fMRI neuroimaging design optimized to test for individual differences (sample N > 100), with task variants that independently assessed proactive and reactive control relative to baseline conditions. Behavioral analyses replicated prior work with the AX-CPT paradigm, in which a measure of target preparation based on contextual cues (the A-cue Bias index) was both reliably increased under task conditions encouraging proactive control and positively associated with WMC. Analyses of fMRI activity indicated that A-cue Bias was selectively linked to increased cue-related neural activity in left motor cortex (lMOT). Additionally, WMC was associated with increased cue-related activation in right dorsolateral prefrontal cortex (rDLPFC), even when statistically controlling for baseline and reactive conditions. The relationship between these two effects was supported by a latent path analysis, which suggested that the rDLPFC-lMOT circuit preferentially mediates the WMC-A-cue Bias relationship present under proactive task conditions. The results suggest this neural circuit may translate strategic task goals into active response preparation as a mechanism of proactive control. Individuals high in WMC may be better able to implement proactive task strategies when instructed via contextual cues. The sensitivity of the rDLPFC-lMOT circuit to individual differences suggest it as a potential target for cognitive enhancement.

Selective attention enables the prioritization of task-relevant information while managing distractors, and steady-state visual evoked potentials (SSVEPs) are widely used to track this process by tagging different visual objects at distinct flicker frequencies. However, whether the choice of tagging frequency itself influences other neural and cognitive measures remains unclear. Here, 27 participants performed detection and 1-back working memory tasks while a central target and peripheral distractors flickered at either 8.6 Hz or 12 Hz. The working memory task produced slower responses, more errors, and greater perceived difficulty than detection. Tagging frequency strongly shaped neural responses, with 8.6 Hz eliciting higher SSVEP signal-to-noise ratios than 12 Hz regardless of stimulus location. Nevertheless, stronger SSVEP responses for centrally attended stimuli were associated with fewer working memory errors and larger early visual ERP responses, while SSVEPs for attended and distractor stimuli were negatively correlated. In addition, the working memory task produced a larger P1-N1 peak-to-peak difference, and tagging frequency altered the timing and amplitude of early ERP effects. Together, these findings show that tagging frequency is not a neutral methodological parameter, but one that shapes both neural indices of attention and their relationship to cognitive performance.

Prior functional magnetic resonance (fMRI) studies examining the neural correlates of retrieval success and precision have reported inconsistent results. Here, we examined the neural correlates of success and precision in a test of memory for spatial location. The present study extended prior findings by employing an experimental design that minimized temporal overlap between mnemonic and visuomotor processing. At study, participants viewed a series of object images, each placed at a randomly selected location on an imaginary circle. At test, studied images were intermixed with new images and presented to the participants. The requirement was to make a covert recognition memory judgment to each image and to attempt to recall its studied location, guessing if necessary. A cue signaling the requirement to make a location memory judgment was presented 4 seconds after image onset. Memory precision was quantified as the angular difference between the studied location and the location selected by the participant. In an analysis that combined the data from the present study and a closely similar prior study, we replicated prior reports that fMRI BOLD activity in the left angular gyrus (AG) and the hippocampus tracks memory precision on a trial-wise basis. Linear mixed effects modeling indicated that the activity in the two regions explained independent sources of variability in these judgments. In addition, multivoxel pattern similarity analysis revealed robust evidence for an item-level reinstatement effect (as indexed by encoding-retrieval overlap) in the left AG that was restricted to items associated with high precision judgments. These findings suggest that the hippocampus and the left AG play non-redundant roles in the retrieval and behavioral expression of high precision episodic memories.

The "default mode" of cognition refers to the tendency to simulate internal experiences, rather than attending to external events in the moment. But in some contexts, external focus can become captivating enough to act as the default mode. To explore the relationship between prepotent internal and external default modes, we measured brain activity in forty participants using fMRI. Naturalistic movie clips were viewed, each one four times in sequence. When subjects were asked to focus attention on the videos, more mind-wandering events (distractions from the externally-focused task) occurred as the videos became less interesting with each repetition, and also when less engaging videos were presented. When subjects were asked to focus internally on breathing, more mind-wandering events (distractions from the internally-focused task) occurred when videos were most interesting (on the first repetition) and when more engaging videos were presented. In the fMRI data, inter-subject correlation, within-subject correlation, and GLM analyses found similar fronto-parietal networks engaged in transitions between default-controlled states regardless of the internal-external distinction, indicating more overlap in internal-external processing than previously assumed. We suggest that whether the default state is internal or external, and whether the sources that disrupt it are internal or external, depend on context.

Linguistic communication is often regarded as an action conveying the speakers communicative goal to the addressee. With both correlational (an fMRI study) and causal (a lesion study) evidence, we demonstrated that communicative goals are represented in human premotor cortex. Participants read scripts each containing a sentence said by the speaker with a goal of either a promise, a request, or a reply. The fMRI results showed that the premotor cortex represented more information on communicative goals than the perisylvian language regions. The lesion study results showed that, relative to healthy controls, the understanding of communicative goals was impaired in patients with lesions in the premotor cortex, whereas no reliable difference between the healthy controls and lesion controls. These findings convergently suggest that the premotor cortex is crucial for representing the goals conveyed by language, supporting the theoretical view that linguistic communication can be seen as a goal-directed action.