Biology subjects

Luna, B.

Publications and source records attributed to Luna, B..

At least 19 recordsLinked to original sources

bioRxiv2026

Cardioselective β-blocker Therapy Resolves Staphylococcus aureus Toxin-Induced Innate Immunoparalysis

During Staphylococcus aureus sepsis, the pore-forming -toxin (Hla) triggers lytic platelet death and provokes the release of catecholamines that modulate leukocyte effector function. The resulting surge in catecholaminergic action paralyzes host antimicrobial capacity by upregulating interleukin-10 (IL-10), profoundly suppressing the protective interferon (IFN) response to orchestrate innate immunoparalysis. Here, we deconvolute a multi-cellular regulatory pathway in the blood and highlight a pivotal immunological checkpoint, where pharmacological intervention with cardioselective {beta}-blockers uncouples the immunosuppressive cascade, restores host antimicrobial function, and significantly improves survival outcomes.

microbiology↗

bioRxiv2026

Developmental Changes in Gray Matter Microstructure and Local Brain Connectivity Support Inhibitory Control from Adolescence to Young Adulthood

Background: Adolescence is marked by improvements in inhibitory control along with brain maturational processes affecting function and structure of cortical circuitry. Preliminary evidence shows a developmental decrease of local neuronal inputs, suggesting a weakening of local connectivity supporting circuit refinement and mature behavior. Microstructural changes in gray matter, arising from processes such as synaptic pruning and myelination, may support this refinement, though it remains unknown how microstructural features interact with the reconfiguration of functional circuitry, or how this unfolds in vivo in normative development to support mature cognitive functioning. Methods: In this study, 175 participants ages 10-26 (93F; 17.32{+/-}4.82yo) completed an anti-saccade task, a developmentally-validated measure of inhibitory control, as well as a 3T MRI scan involving a multi-shell diffusion weighted imaging acquisition, multi-echo resting state fMRI, and structural (T1w, T2w) scans. We computed measures of neurite density (NDI) in gray matter using neurite orientation dispersion and density imaging, local functional connectivity with surface-based and volumetric regional homogeneity (ReHo), and intracortical myelin using T1w/T2w ratio. Generalized additive models examined non-linear age-related trends across a number of cortical and subcortical regions implicated in inhibitory control, as well as associations with anti-saccade performance. Results: We found that NDI significantly increased with age in all regions while ReHo decreased. Greater NDI was associated with more accurate anti-saccade performance and lower ReHo, which remained after residualizing NDI for T1w/T2w ratio, suggesting that microstructural reorganization beyond myelination may underlie functional specialization throughout adolescence. Lower ReHo, specifically in young adolescents, also resulted in better anti-saccade performance. Finally, an interaction between ReHo and NDI, rather than either measure alone, best predicted inhibitory control performance, such that the maturity of neurite density had the greatest effect when local connectivity was high, suggesting immaturity. Conclusions: Our results suggest that the joint maturation of microstructural elements and associated specialization of local functional circuitry interact to support the emergence of stable adult-level inhibitory control.

neuroscience↗

bioRxiv2026

Neurodevelopment of Corticostriatal Circuits and Risk for Alcohol Use During the Transition from Adolescence to Adulthood

Adolescence and early adulthood are marked by rapid neurobehavioral development in reward and decision-making processes, coinciding with the initiation and escalation of alcohol use. While adolescent and young adulthood alcohol initiation is not atypical, adult trajectories diverge: some individuals reduce or discontinue use, whereas others escalate to more frequent or problematic patterns leading to substance use disorders. Corticostriatal circuits, including the ventral striatum (nucleus accumbens; NAcc) and dorsal striatum (caudate and putamen), support reward processing, goal-directed behavior, and habit formation, and are thought to contribute to distinct stages of alcohol use. Yet, how the normative maturation of these circuits relates to alcohol initiation and the transition to habitual consumption remains unclear. We used data from the National Consortium on Alcohol and NeuroDevelopment in Adolescence and Adulthood (NCANDA-A) cohort (822 participants, baseline ages 12 - 22 years old, 1 - 9 visits per participant, 4,356 total visits), a large multisite longitudinal neuroimaging sample spanning adolescence to young adulthood. We observed that rsfMRI functional connectivity (FC) patterns varied systematically across striatal subdivisions: NAcc FC followed an inverted U-shaped trajectory, peaking during adolescence; while caudate and putamen FC showed monotonic decreases with age. Adolescent peak NAcc connectivity was associated with alcohol use initiation, while a lack of normative decrease in putamen connectivity was linked to more frequent alcohol use in adulthood. Together, results suggest that the maturation of reward processing circuitry may support alcohol initiation, while a lack of habit system specialization may contribute to continued alcohol use, with potential implications for the timing of interventions aimed at limiting at-risk drinking.

neuroscience↗

bioRxiv2026

A Scalable fMRI Estimate of Basal Ganglia Brain Tissue Iron for Use in Developmental and Translational Neuroscience

Dopaminergic (DA) function and basal ganglia neurobiology are central to reward learning, motivation, and cognitive control, and dysregulation of these systems contributes to neuropsychiatric conditions that emerge during development. Adolescence is marked by profound reorganization of DAergic basal ganglia circuitry, yet direct in vivo assessment of the DA system remains limited in youth. Brain tissue iron is a developmentally sensitive marker of DA-related neurobiology that can be measured non-invasively via magnetic resonance imaging (MRI). Iron is an essential co-factor for DA synthesis and a foundational metabolic resource that supports cellular metabolism, myelination, and energetic demands of the basal ganglia. T2*-weighted echo-planar imaging (EPI), collected during functional MRI (fMRI), is sensitive to magnetic susceptibility of non-heme brain iron. Leveraging this property, we demonstrate the validity and broad applicability of an iron-sensitive metric that can be derived from conventional single-echo fMRI: {Delta}R2*. In a longitudinal developmental dataset (N = 151; age range 12-31), {Delta}R2* showed high reliability, strong longitudinal stability, and validity via robust convergence with established quantitative relaxometry-based iron measures (R2* and R2). Critically, {Delta}R2* can be retrospectively estimated from extant fMRI data and derived in large-scale consortium data repositories, demonstrated here in the Adolescent Brain and Cognitive Development (ABCD) baseline cohort (N = 8,366; ages 9-11). We show that {Delta}R2* captures known age-related increases in basal ganglia iron, highlighting neurodevelopmental sensitivity at population-scale. Together, these findings establish {Delta}R2* as a reliable, widely accessible marker of basal ganglia iron, enabling scalable investigation of lifespan trajectories and neuropsychiatric risk in existing and future datasets.

neuroscience↗

bioRxiv2026

Trajectories of Response Inhibition Development in Adolescence

Adolescence is a pivotal developmental period during which cognitive control and the ability to suppress maladaptive impulses undergo profound refinement. Despite extensive behavioral and imaging studies in humans, the neural circuit mechanisms that drive the maturation of inhibitory control remain poorly understood. To address this gap, we performed a longitudinal multimodal study in macaque monkeys spanning the transition from puberty to adulthood, combining behavioral measurements, prefrontal neurophysiology, and structural neuroimaging within the same individuals. Behavioral performance in multiple variants of the antisaccade task improved dramatically across adolescence. In parallel, prefrontal cortical neurons exhibited robust developmental increases in task-related firing, particularly around the generation of goal-directed saccades, indicating maturation of neural representations supporting inhibitory control. Strikingly, trajectories of behavioral improvement and neural activity maturation were tightly predicted by the development of long-range white matter pathways linking frontal cortex with distributed brain networks. These findings identify white matter development as a key systems-level mechanism underlying the emergence of mature inhibitory control and prefrontal neural dynamics and establish a primate framework for understanding developmental vulnerabilities associated with neuropsychiatric disorders that emerge in adolescence and early adulthood.

neuroscience↗

bioRxiv2026

Brain criticality emerges with developmental shifts in frequency-specific excitation-inhibition balance

Adolescent brain maturation involves structural changes effecting a shift in excitation/inhibition (E/I) balance, yet the functional implications of these changes remain unclear. One implication is a shift with respect to criticality. Adult brains, at rest, operate near a critical phase transition - at the boundary between an active, excitation-dominant phase, and an absorbing, inhibition-dominant phase. Special properties emerge when neural systems are balanced at criticality, including maximal susceptibility to perturbation, dynamic range, and information transmission. Thus, a clear picture of how adolescent brain maturation affects E/I balance and criticality is needed to understand how maturational processes shape cognition. Here, we leverage the dynamical properties of longitudinally-collected resting-state EEG recordings during N = 310 sessions from 169 healthy human participants ranging in age from 10 to 33 years old to quantify E/I and proximity to criticality. We find that adult brains operate closer to criticality, including spectrally-widespread increases in long-range temporal correlations and amplitude bistability. We also find band-specific changes in excitation versus inhibition whereby the mechanisms driving low-frequency ({theta} to ) oscillations shift towards lower E/I-possibly because of increasing inhibition-while the mechanisms driving high-frequency ({gamma}) oscillations shift towards higher E/I, possibly because of decreasing inhibition. Opening eyes shifts brains towards lower E/I, and these state-dependent shifts are larger in adults. We simulate developmental effects with a neural mass model of coupled excitatory and inhibitory neurons providing a parsimonious account of how changes in brain dynamics could arise as a function of changes in local connectivity of excitatory and inhibitory neurons. Results indicate developmental movement towards criticality, and greater adaptability to state-specific demands, through adolescence to adulthood, reflecting changes in E/I balance with implications for cognitive development.

neuroscience↗

bioRxiv2025

Basal Ganglia Dopamine Availability and Immune Activation Interact and Relate to Anhedonia Severity among Youth with Depression

Anhedonia emerges in adolescence, has putative substrates in neural reward and dopamine systems, and is a hallmark of poor course in depression. Psychoneuroimmunology models suggest altered immune and reward systems may jointly underlie its development. When dopamine availability (rather than function) is considered, immune activation may be understood as a moderator amplifying how lower dopamine levels translate into motivational deficits. This cross-sectional study analyzed data from 55 youth with current depression (Mage=21.4 years; Female=75%). Plasma was assayed for relative quantification of 92 immune proteins, followed by dimensionality reduction via principal component (PC) analysis, forming five PC scores. Dopamine availability was indexed by basal ganglia tissue iron, quantified by MRI R2, a measure detectable in youth. Anhedonia was assessed using the Snaith-Hamilton Pleasure Scale (SHAPS), thought to capture overall anhedonia, and Positive Valence Systems Scale (PVSS), which provides overall, anticipatory, and consummatory anhedonia scores. PC1 scores--whose loadings indicated broadly distributed immune protein elevations consistent with general immune activation--moderated the relationship between basal ganglia dopamine availability and anhedonia: At higher PC1 levels, lower dopamine availability was linked to greater overall anhedonia (as measured by SHAPS) and anticipatory anhedonia, but not to consummatory anhedonia. Lower PC2 scores were associated with greater PVSS overall and consummatory anhedonia. Analyses examining individual basal ganglia regions suggest potential differences in dopaminergic-immune interactions across these regions, with effects most consistently observed in the putamen. Findings highlight nuanced neuroimmune pathways underlying anhedonia components in youth and support inflammation-based models of depression emphasizing dopaminergic-immune interplay.

neuroscience↗

bioRxiv2025

Cross-species evidence for the refinement of intrinsic neural timescales supporting executive system maturation through adolescence

Brain functional, structural, and neurochemical maturation has been found to support the specialization of executive systems through adolescence that will lead to adult level processing. Importantly, animal models and initial EEG studies in humans indicate developmental improvements in neural processing of complex information that would be evident in changes in temporal dynamics, which are not well-understood. Intrinsic neural timescales (INTs), or the temporal windows over which neural populations integrate inputs, have been proposed to reflect circuit-level properties such as excitatory-inhibitory (E/I) balance, myelination, and functional properties supporting complex information processing such as in executive functioning. Here, we used a multimodal, cross-species approach to investigate how INTs develop across adolescence to support cognitive specialization. In parallel analyses using a large longitudinal human EEG cohort, adolescent intracranial sEEG recordings, and macaque local field potentials, we observed robust reductions in INTs through adolescence, particularly in frontal and parietal association cortices. These developmental reductions were shaped by local circuit physiology, as evidenced by associations between shorter INTs and both lower aperiodic exponents, indicative of increased E/I balance, and reduced spectral offsets, suggesting lower aggregate spiking. We also found structural contributions via developmental interactions between age and deep layer intracortical myelination which predicted shorter INTs, suggesting that long-range circuitry may play a key role in shaping spontaneous temporal dynamics. Functionally, shorter INTs in adolescence were linked to improved working memory accuracy and reduced response time variability, indicating a behavioral advantage of refined temporal integration windows through development. Together, these findings establish INTs as a conserved, biologically grounded signature of adolescent brain maturation, providing a mechanistic framework for how structural and physiological refinements reorganize temporal processing to support increasingly efficient cognitive function.

neuroscience↗

bioRxiv2025

Developmental variation in dopamine neurobiology, neurocognitive functioning, and impulsivity shape substance use trajectories in youth

Theoretical neurodevelopmental models implicate increases in dopamine (DA) function and limitations in neurocognitive control in risk-taking behavior, including substance use, during the transition from adolescence to adulthood. However, developmental relationships between DA, neurocognitive control, and the emergence of substance use are poorly understood. Here, we tested the role of basal ganglia tissue iron, reflecting DA neurophysiology, as well as impulsivity and inhibitory control in longitudinal developmental trajectories of substance use. We leveraged the National Consortium on Alcohol and NeuroDevelopment in Adolescence and Adulthood (NCANDA-A) cohort, a large, multisite longitudinal neuroimaging study of 807 participants (baseline ages 12 - 22 years old, 50% female, 1 - 9 annual visits per participant, 6164 sessions total). Substance use, inhibitory control, and tissue iron increased non-linearly during adolescence into young adulthood, concurrent with decreases in impulsivity. Non-linear Growth Mixture Models identified four common trajectories of substance use: low (no- or low levels of use across visits; 30% of participants), youth peak (peak use in adolescence/young adulthood followed by declines; 26%), adolescent increasing (early, steep linear increases in use from adolescence into adulthood; 17%), and adult increasing (low use in adolescence, followed by late linear increases into adulthood; 26%). We show that increased substance use was associated with a phenotype of high impulsivity, low inhibitory control, and low basal ganglia tissue iron, particularly in early adolescence in individuals who displayed youth peak patterns in substance use trajectories. These findings highlight that early developmental differences in DA-related neurobiology and associated impulsivity and cognitive control shape distinct trajectories of adolescent substance use, underscoring adolescence as a critical window for the early identification and implementation of neurodevelopmentally sensitive interventions for substance use disorders.

neuroscience↗

bioRxiv2025

Prefrontal default-mode network interactions with posterior hippocampus during exploration

Hippocampal maps and ventral prefrontal cortex (vPFC) value and goal representations support foraging in continuous spaces. How might hippocampal-vPFC interactions control the balance between behavioral exploration and exploitation? Using fMRI and reinforcement learning modeling, we investigated vPFC and hippocampal responses as humans explored and exploited a continuous one-dimensional space, with out-of-session and out-of-sample replication. The spatial distribution of rewards, or value landscape, modulated activity in the hippocampus and default network vPFC subregions, but not in ventrolateral prefrontal control subregions or medial orbitofrontal limbic subregions. While prefrontal default network and hippocampus displayed higher activity in less complex, easy-to-exploit value landscapes, vPFC-hippocampal connectivity increased in uncertain landscapes requiring exploration. Further, synchronization between prefrontal default network and posterior hippocampus scaled with behavioral exploration. Considered alongside electrophysiological studies, our findings suggest that locations to be explored are identified through coordinated activity binding prefrontal default network value representations to posterior hippocampal maps. Significance StatementThe ventral prefrontal cortex represents goals and values, while the hippocampus contains maps of physical and abstract spaces. In recent years, neuroscientists have sought to understand how hippocampal-prefrontal interactions help us to solve complex problems such as deciding whether to exploit known rewards or explore in search of better alternatives. Using functional magnetic resonance imaging and reinforcement learning modeling, we examine these interactions as humans explore and exploit an environment with a complex distribution of rewards or value landscape. We describe how this value landscape modulates activity and connectivity between prefrontal cortex and hippocampus, controlling the balance between exploration and exploitation.

neuroscience↗

bioRxiv2025

Heterochronous laminar maturation in the human prefrontal cortex

The human prefrontal cortex (PFC) exhibits markedly protracted developmental plasticity, yet whether reductions in plasticity occur synchronously across prefrontal cortical layers is unclear. Animal studies have shown that intracortical myelin consolidates developing circuits by restricting ongoing neuronal plasticity. Here, we use longitudinal myelin-sensitive imaging collected at ultra-high field to investigate whether superficial and deep PFC layers exhibit different timeframes of malleability. We find that myelin matures earlier in deep than in superficial compartments of the cortical ribbon; this laminar divergence in maturational timing is differentially expressed across cytoarchitecturally and functionally distinct frontal regions. By integrating myelin mapping with EEG and behavioral phenotyping, we provide evidence that prefrontal myelin impacts timescales of neural activity, task learning rates, and cognitive processing speed. Heterochronous myelination across deep and superficial layers is an underrecognized mechanism through which human association cortex balances cognitively-relevant increases in circuit stability and efficiency with extended neuroplasticity.

neuroscience↗

bioRxiv2025

Maturation of striatal dopamine supports the development of habitual behavior through adolescence

Developmental trajectories during the transition from adolescence to adulthood contribute to the establishment of stable, adult forms of operation. Understanding the neural mechanisms underlying this transition is crucial for identifying variability in normal development and the onset of psychiatric disorders, which typically emerge during this time. Habitual behaviors can serve as a model for understanding brain mechanisms underlying the stabilization of adult behavior, while also conferring risk for psychopathologies. Dopaminergic (DA) processes in the basal ganglia are thought to facilitate the formation of habits; however, developmental trajectories of habits and the brain systems supporting them have not been characterized in vivo in developing humans. The current study examined trajectories of habitual behavior from adolescence to adulthood and sought to understand how the maturing striatal DA system may act as a potential mechanism in the process of habit formation. We used data from two longitudinal studies (combined n = 217, 10 - 32 years of age, 1-3 visits each, 320 total sessions) to characterize normative developmental trajectories of basal ganglia tissue iron concentration (a proxy for DA-related neurophysiology) and goal-direct and habitual control behaviors in a two-stage decision-making task. Tissue iron concentrations across the basal ganglia and habitual responding during the two-stage sequential decision-making task both increased with age (all p < 0.001). Importantly, habitual responding was associated with tissue iron concentrations in the putamen (F = 4.34, p = 0.014), such that increases in habitual responding were supported by increases in putamen tissue iron concentration during childhood through late adolescence. Exploratory analyses of further subdivisions of anatomical regions found that this association was specific to the posterior putamen. These results provide novel evidence in humans that habitual behavior continues to mature into adulthood and may be supported by increased specialization of reward systems.

neuroscience↗

bioRxiv2024

Brain structure and activity predicting cognitive maturation in adolescence

Cognitive abilities of primates, including humans, continue to improve through adolescence 1,2. While a range of changes in brain structure and connectivity have been documented 3,4, how they affect neuronal activity that ultimately determines performance of cognitive functions remains unknown. Here, we conducted a multilevel longitudinal study of monkey adolescent neurocognitive development. The developmental trajectory of neural activity in the prefrontal cortex accounted remarkably well for working memory improvements. While complex aspects of activity changed progressively during adolescence, such as the rotation of stimulus representation in multidimensional neuronal space, which has been implicated in cognitive flexibility, even simpler attributes, such as the baseline firing rate in the period preceding a stimulus appearance had predictive power over behavior. Unexpectedly, decreases in brain volume and thickness, which are widely thought to underlie cognitive changes in humans 5 did not predict well the trajectory of neural activity or cognitive performance changes. Whole brain cortical volume in particular, exhibited an increase and reached a local maximum in late adolescence, at a time of rapid behavioral improvement. Maturation of long-distance white matter tracts linking the frontal lobe with areas of the association cortex and subcortical regions best predicted changes in neuronal activity and behavior. Our results provide evidence that optimization of neural activity depending on widely distributed circuitry effects cognitive development in adolescence.

neuroscience↗

bioRxiv2024

Prefrontal Excitation/ Inhibition Balance Supports Adolescent Enhancements in Circuit Signal to Noise Ratio

The development and refinement of neuronal circuitry allow for stabilized and efficient neural recruitment, supporting adult-like behavioral performance. During adolescence, the maturation of PFC is proposed to be a critical period (CP) for executive function, driven by a break in balance between glutamatergic excitation and GABAergic inhibition (E/I) neurotransmission. During CPs, cortical circuitry fine-tunes to improve information processing and reliable responses to stimuli, shifting from spontaneous to evoked activity, enhancing the SNR, and promoting neural synchronization. Harnessing 7T MR spectroscopy and EEG in a longitudinal cohort (N = 164, ages 10-32 years, 283 neuroimaging sessions), we outline associations between age-related changes in glutamate and GABA neurotransmitters and EEG measures of cortical SNR. We find developmental decreases in spontaneous activity and increases in cortical SNR during our auditory steady state task using 40 Hz stimuli. Decreases in spontaneous activity were associated with glutamate levels in DLPFC, while increases in cortical SNR were associated with more balanced Glu and GABA levels. These changes were associated with improvements in working memory performance. This study provides evidence of CP plasticity in the human PFC during adolescence, leading to stabilized circuitry that allows for the optimal recruitment and integration of multisensory input, resulting in improved executive function.

neuroscience↗

bioRxiv2023

Aperiodic EEG and 7T MRSI evidence for maturation of E/I balance supporting the development of working memory through adolescence

Postmortem animal and human models suggest changes through adolescence in aspects of excitatory glutamatergic and inhibitory GABAergic function (E/I) in prefrontal cortex (PFC) suggestive of critical period plasticity at a time of significant cognitive development. Recently, using high field 7T Magnetic Resonance Spectroscopic Imaging (MRSI), we found in vivo evidence for increases in PFC glutamate/GABA balance through adolescence into adulthood. We now extend these MRSI findings by investigating, in the same 164 10- 32-year-old participants, its correspondence with EEG aperiodic activity, an independent measure of E/I balance elucidating changes in neural activity. Results showed decreases in PFC aperiodic activity from adolescence to adulthood, that were associated with MRSI measures of glutamate/GABA balance as well as mediating the association between age and EEG aperiodic activity. Further, changes in aperiodic activity predicted performance on a working memory task, indicating a role for E/I based changes in PFC signaling mechanisms in supporting maturation of cognitive control. Taken together, these results suggest that PFC is undergoing critical period plasticity through adolescence evident in both neurotransmitter and neural function that supports cognitive development.

neuroscience↗

bioRxiv2023

Multivariate and Regional Age-Related Change in Basal Ganglia Iron in Neonates

In the perinatal period, reward and cognitive systems begin trajectories, influencing later psychiatric risk. The basal ganglia is important for reward and cognitive processing but early development has not been fully characterized. To assess age-related development, we used a measure of basal ganglia physiology, specifically brain tissue iron, obtained from nT2* signal in rsfMRI, associated with dopaminergic processing. We used data from the Developing Human Connectome Project (N=464) to assess how moving from the prenatal to the postnatal environment affects rsfMRI nT2*, modeling gestational and postnatal age separately for basal ganglia subregions in linear models. We did not find associations with tissue iron and gestational age [Range: 24.29-42.29] but found positive associations with postnatal age [Range:0-17.14] in the pallidum and putamen, but not the caudate. We tested if there was an interaction between preterm birth and postnatal age, finding early preterm infants (GA<35 weeks) had higher iron levels and changed less over time. To assess multivariate change, we used support vector regression to predict age from voxel-wise-nT2* maps. We could predict postnatal but not gestational age when maps were residualized for the other age term. This provides evidence subregions differentially change with postnatal experience and preterm birth may disrupt trajectories.

neuroscience↗

bioRxiv2023

Gestational and postnatal age associations for striatal tissue iron deposition in early infancy

Striatal development is crucial for later motor, cognitive, and reward behavior, but age-related change in striatal physiology during the neonatal period remains understudied. An MRI-based measure of tissue iron deposition, T2*, is a non-invasive way to probe striatal physiology neonatally, linked to dopaminergic processing and cognition in children and adults. Striatal subregions have distinct functions that may come online at different time periods in early life. To identify if there are critical periods before or after birth, we measured if striatal iron accrued with gestational age at birth [range=34.57-41.85 weeks] or postnatal age at scan [range=5-64 days], using MRI to probe the T2* signal in N=83 neonates in three striatal subregions. We found iron increased with postnatal age in the pallidum and putamen but not the caudate. No significant relationship between iron and gestational age was observed. Using a subset of infants scanned at preschool age (N=26), we show distributions of iron shift between timepoints. In infants, the pallidum had the least iron of the three regions but had the most by preschool age. Together, this provides evidence of distinct change for striatal subregions, a possible differentiation between motor and cognitive systems, identifying a mechanism that may impact future trajectories. HighlightsO_LINeonatal striatal tissue iron can be measured using the T2* signal from rsfMRI C_LIO_LInT2* changed with postnatal age in the pallidum and putamen but not in the caudate C_LIO_LInT2* did not change with gestational age in any of the three regions C_LIO_LIPatterns of iron deposition (nT2*) among regions shift from infancy to preschool C_LI

neuroscience↗

bioRxiv2023

Reinforcement-based option competition in human dorsal stream during exploration/exploitation of a continuous space

Primates exploring and exploiting a continuous sensorimotor space rely on maps in the dorsal stream that guide visual search, locomotion, and grasp. For example, an animal swinging from one tree limb to the next uses rapidly evolving sensorimotor representations to decide when to harvest a reward. We show that such exploration/exploitation depends on dynamic maps of competing option values in the human dorsal stream. Using a reinforcement learning (RL) model capable of rapid learning and efficient exploration and exploitation, we show that preferred options are selectively maintained on the map while the values of spatiotemporally distant alternatives are compressed. Consistent with biophysical models of cortical option competition, dorsal stream BOLD signal increased and posterior cortical {beta}1/ oscillations desynchronized as the number of potentially valuable options grew, matching predictions of information-compressing RL rather than traditional RL that caches long-term values. BOLD and {beta}1/ responses were correlated and predicted the successful transition from exploration to exploitation. These option competition dynamics were observed across parietal and frontal dorsal stream regions, but not in the occipito-temporal MT+ sensitive to the average reward rate. Our results also illustrate that models diverging predictions about information dynamics can help to adjudicate between them based on population activity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/541828v1_ufig1.gif" ALT="Figure 1"> View larger version (74K): org.highwire.dtl.DTLVardef@155b3c8org.highwire.dtl.DTLVardef@18e28c5org.highwire.dtl.DTLVardef@16d7c1org.highwire.dtl.DTLVardef@1aed684_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗