Biology subjects

Bunge, S.

Publications and source records attributed to Bunge, S..

8 recordsLinked to original sources

bioRxiv2026

What is common to memory retrieval and relational reasoning? Testing neural overlap in anterior lateral prefrontal cortex

Anterior lateral prefrontal cortex (aLPFC) has been consistently implicated in retrieval monitoring and relational reasoning. However, it is unknown whether aLPFC supports a cognitive process that is common to memory retrieval and reasoning tasks. To inform this question, a first step is to ascertain whether there is, within individuals, spatial overlap in aLPFC between tasks. A prior study found overlap in activation of left aLPFC between verbal analogy and source memory retrieval tasks, using tightly matched word stimuli (Westphal et al., 2016). To assess whether this overlap in activation extends to other stimulus types and task designs, and another sensory modality, we collected fMRI data from 35 healthy young adults as they completed an associative memory retrieval task along with four variants of a relational reasoning paradigm that reliably engages left aLPFC. The reasoning tasks followed a 2 (visual/auditory modality) x 2 (spatial/featural relations) x 2 (low/high relational complexity) design. In the associative memory task, participants studied word pairs and decided whether the two words were related. At retrieval, they viewed pairs of previously seen words and judged whether the pair was Intact (words paired together at encoding) or Recombined (previously seen words recombined into new pairs). Response times were slower for Recombined vs. Intact pairs, consistent with heightened retrieval monitoring. As predicted, aLPFC was more active for Recombined than Intact pairs, as well as for the manipulation of relational complexity across the four reasoning tasks. A group-level conjunction analysis demonstrated substantial overlap between memory and reasoning manipulations in left aLPFC (Glasser parcels a47r, p47r, a10p, and p10p). Within individuals, clusters defined from the reasoning task were also sensitive to retrieval monitoring demands. Further, there was within-participant overlap in the pattern of active vertices, as measured via Dice coefficients. Bayes factor testing within each parcel of interest demonstrated greater vertex-level overlap than expected by chance, particularly in p47r. Importantly, degree of overlap varied widely among individuals, and exploratory results showed that both cluster-level activation and vertex overlap in p47r correlated with memory discriminability (d-prime). Thus, we hypothesize that neural overlap in this area reflects engagement in relational thinking during memory retrieval monitoring. Together, these results move beyond general characterizations of aLPFC function by testing whether it meets a precondition -- individual-level neural overlap across varied tasks -- of a unified neurocognitive function in support of reasoning and memory retrieval.

neuroscience↗

bioRxiv2026

Modular functional brain network organization contributes to training-related changes in task switching in children

Cognitive training often aims to improve cognitive skills, but outcomes have been variable in terms of their success. One factor that has been found to predict training outcomes is the degree of modularity of functional brain networks, defined as the extent to which brain regions are more strongly connected to regions within the same functional subnetwork than to regions outside of the subnetwork. Specifically, more modular organization of functional brain networks at baseline has been associated with greater benefits from cognitive training in adults. During childhood, cognitive development is marked by a slow progression towards network integration and segregation, which together contribute to increasing modularity. Thus, network modularity might also be an important predictor of training outcomes in children. To investigate whether individual differences in network modularity predict training outcomes in children, we examined 84 children aged 8 to 11 years who completed nine weeks of either high-intensity task-switching training or high-intensity single-task training. Prior to training, children showed lower network modularity than adults, in line with previously reported developmental changes in network configuration. With training, performance improved, especially in the high-intensity task-switching group. More modular organization of functional brain networks before training was associated with faster improvements in task-switching performance, especially at the beginning of training. These results suggest that more modular functional networks might allow for faster adaptation to training demands in children and thus faster improvements with training. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=180 SRC="FIGDIR/small/708262v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@ac568aorg.highwire.dtl.DTLVardef@658bb4org.highwire.dtl.DTLVardef@b6eb24org.highwire.dtl.DTLVardef@1079a4a_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Intensive training improved task-switching performance in children. - Children showed less modular network organization than adults. - More modular networks before training were associated with faster training gains. - Children with more modular networks adapted more quickly to training demands.

neuroscience↗

bioRxiv2026

Evaluating the reliability of functional near-infrared spectroscopy data in the context of a reasoning paradigm

Functional near-infrared spectroscopy (fNIRS) is a portable, motion-tolerant neuroimaging method particularly well suited for developmental and naturalistic research. To evaluate the utility of fNIRS for studying individual differences and longitudinal changes, we measured activation and functional connectivity during a relational reasoning task in young adults (N = 73). We sought to (1) establish whether fNIRS captures frontoparietal activation patterns consistent with prior fMRI studies using similar paradigms, (2) assess the effect of the amount of data (number of task blocks) on signal strength and precision, (3) assess the paradigms measurement properties in the form of intra- and interindividual stability of activation and functional connectivity within and across testing sessions, and (4) examine whether grouping channels into anatomical regions of interest (ROIs) conferred benefits to the above. We observed robust task-evoked activation across lateral prefrontal and parietal cortices, with effect sizes on par with prior fMRI studies. Generally, we observed diminishing returns in effect size and measurement precision beyond [~]7 minutes. Internal consistency and test-retest reliability varied across metrics; while they were very low for a specific task contrast, they were extremely high for functional connectivity, confirming the robustness of channel- and ROI-level connectivity as a stable marker of functional architecture. Exploratory analyses supported prior observations of lower signal quality in participants with darker skin tones and hair, underscoring the need for inclusive methodological strategies. Together, these findings highlight key design considerations for optimizing longitudinal and individual-differences research on higher-level cognition, particularly in diverse and developmentally variable populations. HighlightsO_LIWe measured within- and between-session reliability of fNIRS metrics C_LIO_LICollecting more data yielded diminishing returns in effect size and precision C_LIO_LIThere were tradeoffs to aggregating channel data into regions of interest C_LIO_LIGeneral task activation was more reliable than a specific task contrast C_LIO_LIFunctional connectivity showed extremely high test-retest reliability C_LI

neuroscience↗

bioRxiv2024

Lateral frontoparietal functional connectivity based on individual sulcal morphology

A salient neuroanatomical feature of the human brain is its pronounced cortical folding, and there is mounting evidence that sulcal morphology is relevant to functional brain architecture and cognition. However, our understanding of the relationships between sulcal anatomy, brain activity, and behavior is still in its infancy. We previously found the depth of three small, shallow sulci in lateral prefrontal cortex (LPFC) was linked to reasoning performance in childhood and adolescence (Voorhies et al., 2021). These findings beg the question: what is the linking mechanism between sulcal morphology and cognition? To shed light on this question, we investigated functional connectivity among sulci in LPFC and lateral parietal cortex (LPC). We leveraged manual parcellations (21 sulci/hemisphere, total of 1806) and functional magnetic resonance (fMRI) data from a reasoning task from 43 participants aged 7-18 years (20 female). We conducted clustering and classification analyses of individual- level functional connectivity among sulci. Broadly, we found that 1) the connectivity patterns of individual sulci could be differentiated - and more accurately than rotated sulcal labels equated for size and shape; 2) sulcal connectivity did not consistently correspond with that of probabilistic labels or large-scale networks; 3) sulci clustered together into groups with similar patterns, not dictated by spatial proximity; and 4) across individuals, greater depth was associated with higher network centrality for several sulci under investigation. These results highlight that functional connectivity can be meaningfully anchored to individual sulcal anatomy, and demonstrate that functional network centrality can vary as a function of sulcal depth. Significance StatementA salient, and behaviorally relevant, feature of the human brain is its pronounced cortical folding. However, the links between sulcal anatomy and brain function are still poorly understood - particularly for small, shallow, individually variable sulci in association cortices. Here, focusing on individually defined sulci in lateral prefrontal and parietal regions, we offer a novel, anatomically informed approach to defining functional connectomes. Further, we demonstrate, for the first time, a link between functional network centrality and sulcal morphology.

neuroscience↗

bioRxiv2023

Task-Switch Related Reductions in Neural Distinctiveness in Children and Adults: Commonalities and Differences

Goal-directed behavior requires the ability to flexibly switch between task sets with changing environmental demands. Switching between tasks generally comes at the cost of slower and less accurate responses. Compared to adults, children show greater switch costs, presumably reflecting the protracted development of the ability to flexibly update task-set representations. To examine whether the distinctiveness of neural task-set representations is more strongly affected by a task switch in children compared to adults, we examined multi-voxel patterns of fMRI activation in 88 children (8-11 years, 49 girls) and 53 adults (20-30 years, 28 women) during a task-switching paradigm. Using multivariate pattern analysis (MVPA), we investigated whether task-set representations were less distinct on switch than on repeat trials across frontoparietal, cingulo-opercular, and temporo-occipital regions. Children and adults showed lower accuracy and longer response times on switch than on repeat trials, with higher accuracy costs in children. Decoding accuracy across regions was lower on switch than repeat trials, consistent with the notion that switching reduces the distinctiveness of task-set representations. Reliable age differences in switch-related representational distinctiveness reductions were absent, pointing to a remarkable degree of maturity of neural representations of task-relevant information in late childhood. However, we also observed that switch-related reductions in distinctiveness were more highly correlated across frontoparietal and cingulo-opercular regions in children than in adults, potentially reflecting the ongoing specialization of different control networks with respect to the representation of task features. Significance statementThe ability to flexibly switch between tasks enables goal-directed behavior, but is particularly challenging for children, potentially due to protracted development in the ability to represent multiple and overlapping task rules that link stimuli to appropriate responses. We tested this hypothesis by using neuroimaging to measure brain activity during task switching in 8-11-year-olds and adults. Activation patterns in frontal, parietal, and temporal regions could tell us with above-chance accuracy which task a person was performing when the task remained the same, but not when it had switched. Adults showed greater differentiation across regions in terms of switch-related reductions in distinctiveness than children, suggesting that the relevant functional circuity is present but has not yet fully matured by late childhood.

neuroscience↗

bioRxiv2022

Does prefrontal connectivity during task switching help or hinder children's performance?

The ability to flexibly switch between tasks is key for goal-directed behavior and continues to improve across childhood. Childrens task switching difficulties are thought to reflect less efficient engagement of sustained and transient control processes, resulting in lower performance on blocks that intermix tasks (sustained demand) and trials that require a task switch (transient demand). Sustained and transient control processes are associated with frontoparietal regions, which develop throughout childhood and may contribute to task switching development. We examined age differences in the modulation of frontoparietal regions by sustained and transient control demands in children (8-11 years) and adults. Children showed greater performance costs than adults, especially under sustained demand, along with less upregulation of sustained and transient control activation in frontoparietal regions. Compared to adults, children showed increased connectivity between the inferior frontal junction (IFJ) and lateral prefrontal cortex (lPFC) from single to mixed blocks. For children whose sustained activation was less adult-like, increased IFJ-lPFC connectivity was associated with better performance. Children with more adult-like sustained activation showed the inverse effect. These results suggest that individual differences in task switching in later childhood at least partly depend on the recruitment of frontoparietal regions in an adult-like manner.

neuroscience↗

bioRxiv2022

Superficial white matter across the lifespan: volume, thickness, change, and relationship with cortical features

Superficial white matter (SWM) represents a significantly understudied part of the human brain, despite comprising a large portion of brain volume and making up a majority of cortical structural connections. Using multiple, high-quality, datasets with large sample sizes (N=2421, age range 5-100) in combination with methodological advances in tractography, we quantified features of SWM volume and thickness across the brain and across the lifespan. We address four questions: (1) How does U-fiber volume change with age? (2) What does U-fiber thickness look like across the brain? (3) How does SWM thickness change with age? (4) Are there relationships between SWM thickness and cortical features? Our main findings are that (1) SWM volume shows unique volumetric trajectories with age that are distinct from gray matter and other white matter trajectories; (2) SWM thickness varies across the brain, with patterns robust across individuals and across the population at the region-level and vertex-level; (3) SWM shows nonlinear changes across the lifespan that vary across regions; and (4) SWM thickness is associated with cortical thickness and curvature. For the first time, we show that SWM volume follows a similar trend as overall white matter volume, peaking at a similar time in adolescence, leveling off throughout adulthood, and decreasing with age thereafter. Notably, the relative fraction of total brain volume of SWM continuously increases with age, and consequently takes up a larger proportion of total white matter volume, unlike the other tissue types that decrease with respect to total brain volume. This study represents the first characterization of SWM features across the lifespan and provides the background for characterizing normal aging and insight into the mechanisms associated with SWM development and decline.

neuroscience↗

bioRxiv2021

A new tripartite landmark in posterior cingulate cortex

Understanding brain structure-function relationships, and their development and evolution, is central to neuroscience research. Here, we show that morphological differences in posterior cingulate cortex (PCC), a hub of functional brain networks, predict individual differences in macroanatomical, microstructural, and functional features of PCC. Manually labeling 4,319 sulci in 552 hemispheres, we discovered a consistently localized shallow cortical indentation (termed the inframarginal sulcus; ifrms) within PCC that is absent from neuroanatomical atlases, yet co-localized with a region within the cognitive control, but not default mode, network. Morphological analyses in humans and chimpanzees showed that unique properties of the ifrms differ across the lifespan and between hominoid species. Intriguingly, the consistency of the ifrms also debunks the uniqueness of the morphology of Einsteins PCC. These findings support a classic theory that shallow, tertiary sulci serve as landmarks in association cortices. They also beg the question: how many other cortical indentations have we missed?

neuroscience↗