Author name cluster

Beatriz Luna

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

20 papers

1 author row

YNIMG Journal 2023 Journal Article

Age-related differences in transient gamma band activity during working memory maintenance through adolescence

Shane D. McKeon
Finnegan Calabro
Ryan V. Thorpe
Alethia de la Fuente
Will Foran
Ashley C. Parr
Stephanie R. Jones
Beatriz Luna

Adolescence is a stage of development characterized by neurodevelopmental specialization of cognitive processes. In particular, working memory continues to improve through adolescence, with increases in response accuracy and decreases in response latency continuing well into the twenties. Human electroencephalogram (EEG) studies indicate that gamma oscillations (35-65 Hz) during the working memory delay period support the maintenance of mnemonic information guiding subsequent goal-driven behavior, which decrease in power with development. Importantly, recent electrophysiological studies have shown that gamma events, more so than sustained activity, may underlie working memory maintenance during the delay period. However, developmental differences in gamma events during working memory have not been studied. Here, we used EEG in conjunction with a novel spectral event processing approach to investigate age-related differences in transient gamma band activity during a memory guided saccade (MGS) task in 164 10- to 30-year-olds. Total gamma power was found to significantly decrease through adolescence, replicating prior findings. Results from the spectral event pipeline showed age-related decreases in the mean power of gamma events and trial-by-trial power variability across both the delay period and fixation epochs of the MGS task. In addition, we found that while event number decreased with age during the fixation period, the developmental decrease during the delay period was more dramatic, resulting in an increase in event spiking from fixation to delay in adolescence but not adulthood. While average power of the transient gamma events was found to mediate age-related differences in total gamma power in the fixation and delay periods, the number of gamma events was related to total power in only the delay period, suggesting that the power of gamma events may underlie the sustained gamma activity seen in EEG literature while the number of events may directly support age-related improvements in working memory maintenance. Our findings provide compelling new evidence for mechanistic changes in neural processing characterized by refinements in neural function as behavior becomes optimized in adulthood.

YNIMG Journal 2023 Journal Article

Striatal dopamine supports reward expectation and learning: A simultaneous PET/fMRI study

Finnegan J Calabro
David F Montez
Bart Larsen
Charles M Laymon
William Foran
Michael N Hallquist
Julie C Price
Beatriz Luna

C]Raclopride (RAC), assessing striatal dopamine (DA) D2/3 receptor binding, during performance of a probabilistic reward learning task. Both fMRI activation and PET DA measures showed ventral striatum involvement for signaling rewards. However, greater DA release was uniquely associated with learning strategies (i.e., learning rates) that were more task-optimal within the best fitting reinforcement learning model. This DA response was associated with BOLD activation of a network of regions including anterior cingulate cortex, medial prefrontal cortex, thalamus and posterior parietal cortex, primarily during expectation, rather than prediction error, task epochs. Together, these data provide novel, human in vivo evidence that striatal dopaminergic signaling interacts with a network of cortical regions to generate task-optimal learning strategies, rather than representing reward outcomes in isolation.

YNIMG Journal 2021 Journal Article

Inter-individual variability in structural brain development from late childhood to young adulthood

Kathryn L. Mills
Kimberly D. Siegmund
Christian K. Tamnes
Lia Ferschmann
Lara M. Wierenga
Marieke G.N. Bos
Beatriz Luna
Chun Li

A fundamental task in neuroscience is to characterize the brain's developmental course. While replicable group-level models of structural brain development from childhood to adulthood have recently been identified, we have yet to quantify and understand individual differences in structural brain development. The present study examined inter-individual variability and sex differences in changes in brain structure, as assessed by anatomical MRI, across ages 8.0-26.0 years in 269 participants (149 females) with three time points of data (807 scans), drawn from three longitudinal datasets collected in the Netherlands, Norway, and USA. We further investigated the relationship between overall brain size and developmental changes, as well as how females and males differed in change variability across development. There was considerable inter-individual variability in the magnitude of changes observed for all examined brain measures. The majority of individuals demonstrated decreases in total gray matter volume, cortex volume, mean cortical thickness, and white matter surface area in mid-adolescence, with more variability present during the transition into adolescence and the transition into early adulthood. While most individuals demonstrated increases in white matter volume in early adolescence, this shifted to a majority demonstrating stability starting in mid-to-late adolescence. We observed sex differences in these patterns, and also an association between the size of an individual's brain structure and the overall rate of change for the structure. The present study provides new insight as to the amount of individual variance in changes in structural morphometrics from late childhood to early adulthood in order to obtain a more nuanced picture of brain development. The observed individual- and sex-differences in brain changes also highlight the importance of further studying individual variation in developmental patterns in healthy, at-risk, and clinical populations.

YNIMG Journal 2020 Journal Article

Meta-analysis and review of functional neuroimaging differences underlying adolescent vulnerability to substance use

Brenden Tervo-Clemmens
Alina Quach
Finnegan J. Calabro
William Foran
Beatriz Luna

Adolescence is increasingly viewed as a sensitive period in the development of substance use disorders (SUDs). Neurodevelopmental ‘dual-risk’ theories suggest adolescent vulnerability to problematic substance use is driven by an overactive reward drive mediated by the striatum, and poor cognitive control mediated by the prefrontal cortex. To this end, there has been a growing number of neuroimaging studies examining cognitive and affective neural systems during adolescence for markers of vulnerability to problematic substance use. Here, we perform a coordinate-based meta-analysis on this emerging literature. Twenty-two task-based voxelwise fMRI studies with activation differences associated with substance use vulnerability, representative of approximately 1092 subjects, were identified through a systematic literature search (PubMed, Scopus) and coordinates of activation differences (N = 190) were extracted. Adolescents were defined as ‘at-risk’ for problematic substance use based on a family history of SUD or through prospective prediction of substance use initiation or escalation. Multilevel kernel density analysis was used to identify the most consistent brain regions associated with adolescent substance use vulnerability. Across the included studies, substance use vulnerability was most reliably associated with activation differences in the striatum, where at-risk adolescents had hyper-activation in the dorsal subdivision (putamen). Follow-up analyses suggested striatal differences were driven by tasks sharing a motivational and/or reward component (e. g. , monetary incentive) and common across subgroups of substance use risk (family history and prospective prediction studies). Analyses examining the role of psychiatric comorbidity revealed striatal activation differences were significantly more common in samples whose definition of substance use risk included cooccurring externalizing psychopathology. Furthermore, substance use risk meta-analytic results were no longer significant when excluding these studies, although this may reflect limitations in statistical power. No significant activation differences were observed in prefrontal cortex in any analysis. These results suggest striatal dysfunction, rather than prefrontal, may be a more primary neural feature of adolescent vulnerability to problematic substance use, possibly through a dimension of individual variability shared with externalizing psychopathology. However, our systematic literature search confirms this is still an emerging field. More studies, increased data sharing, and further quantitative integration are necessary for a comprehensive understanding of the neuroimaging markers of adolescent substance use risk.

YNIMG Journal 2020 Journal Article

Representational similarity analysis reveals atypical age-related changes in brain regions supporting face and car recognition in autism

Kirsten O’Hearn
Bart Larsen
Jennifer Fedor
Beatriz Luna
Andrew Lynn

Background Autism Spectrum Disorder (ASD) is associated with atypical activation in the ventral stream during face processing. The current study further characterizes the development of face processing in ASD using a multivoxel pattern analysis, which assesses the similarity in the representation of exemplars from the same category. Methods Ninety-two children, adolescents and adults - with and without ASD - performed the Cambridge Face Memory Test, the Australian Face Memory Test, and a matched car memory test. Regions of interest during these tasks included Fusiform Face Area (FFA), based on the literature, and additional, structurally-defined regions in the ventral stream. Group differences in the patterns of activity within these ROIs when memorizing exemplars were examined using a representational similarity analysis (RSA). Results The RSA revealed significant interactions between age group and diagnostic group in R FFA, with increasing similarity within a category (faces, cars) into adulthood typically but not in those with ASD. This pattern was also evident in structurally defined ventral stream regions, namely L inferior frontal gyrus (IFG), bilateral temporoparietal junction (TPJ), L inferior temporal lobule, and the R fusiform gyrus. Conclusions The specialization of face and object processing from adolescence to adulthood evident in typical development may be impaired in ASD, undermining the ability to reach adult-level visual processing in those with ASD.

RLDM Conference 2019 Conference Abstract

Anterior vs. posterior hippocampal contributions to reinforcement learning on a timing task

Alexandre Y Dombrovski
Beatriz Luna

The human hippocampus is a phylogenetically ancient medial temporal lobe structure. Hip- pocampal place cells and grid cells in the adjacent entorhinal cortex (EC) support spatial navigation. Recent studies implicate them in the formation and navigation of abstract spaces, including those defined by time. The hippocampal posterior-anterior long axis is thought to be organized along a functional gradient from smaller to larger spatial scales, from non-semantic to semantic associations, and from detailed to gist memo- ries. Whereas hippocampus is thought to be important for reinforcement learning in complex spaces, we do not know the specific computational roles of its anterior vs. posterior divisions. Employing a reinforcement- based timing task and fMRI, we investigated the roles of anterior vs. posterior hippocampus in the transition from initial exploration to exploitation. We modeled behavior with the SCEPTIC RL model (Hallquist & Dombrovski, 2019). Posterior hippocampus responded to reward prediction errors, and its activity strongly predicted reinforcement-driven shifts in response times. Anterior hippocampus, by contrast, responded to low entropy of response time values, indicating a strong global maximum, and its activity predicted a con- vergence of response times on this maximum. Thus, as humans form and exploit a cognitive space along the dimensions of time and value, posterior hippocampus subserves shifts driven by prediction errors whereas anterior hippocampus facilitates convergence on the global value maximum.

YNIMG Journal 2019 Journal Article

Image processing and analysis methods for the Adolescent Brain Cognitive Development Study

Donald J. Hagler
SeanN. Hatton
M. Daniela Cornejo
Carolina Makowski
Damien A. Fair
Anthony Steven Dick
Matthew T. Sutherland
B.J. Casey

The Adolescent Brain Cognitive Development (ABCD) Study is an ongoing, nationwide study of the effects of environmental influences on behavioral and brain development in adolescents. The main objective of the study is to recruit and assess over eleven thousand 9-10-year-olds and follow them over the course of 10 years to characterize normative brain and cognitive development, the many factors that influence brain development, and the effects of those factors on mental health and other outcomes. The study employs state-of-the-art multimodal brain imaging, cognitive and clinical assessments, bioassays, and careful assessment of substance use, environment, psychopathological symptoms, and social functioning. The data is a resource of unprecedented scale and depth for studying typical and atypical development. The aim of this manuscript is to describe the baseline neuroimaging processing and subject-level analysis methods used by ABCD. Processing and analyses include modality-specific corrections for distortions and motion, brain segmentation and cortical surface reconstruction derived from structural magnetic resonance imaging (sMRI), analysis of brain microstructure using diffusion MRI (dMRI), task-related analysis of functional MRI (fMRI), and functional connectivity analysis of resting-state fMRI. This manuscript serves as a methodological reference for users of publicly shared neuroimaging data from the ABCD Study.

YNIMG Journal 2018 Journal Article

Adolescent cannabis use and brain systems supporting adult working memory encoding, maintenance, and retrieval

Brenden Tervo-Clemmens
Daniel Simmonds
Finnegan J. Calabro
Nancy L. Day
Gale A. Richardson
Beatriz Luna

Given prior reports of adverse effects of cannabis use on working memory, an executive function with a protracted developmental course during adolescence, we examined associations between developmental patterns of cannabis use and adult working memory (WM) processes. Seventy-five adults with longitudinal assessments of cannabis use (60 with reported use, 15 with no reported use) and prenatal drug exposure assessment completed a spatial WM task during fMRI at age 28. All subjects passed a multi-drug urine screen on the day of testing and denied recreational drug use in the past week. A fast event-related design with partial trials was used to separate the BOLD response associated with encoding, maintenance, and retrieval periods of the WM task. Behavioral results showed that subjects who began using cannabis earlier in adolescence had longer reaction times (RT) than those with later initiation. Cannabis age of onset was further associated with reduced posterior parietal cortex (PPC) encoding BOLD activation, which significantly mediated age of onset WM RT associations. However, cannabis age of onset brain-behavior associations did not differ between groups with a single reported use and those with repeated use, suggesting age of onset effects may reflect substance use risk characteristics rather than a developmentally-timed cannabis exposure effect. Within repeated cannabis users, greater levels of total cannabis use were associated with performance-related increases in dorsolateral prefrontal cortex (DLPFC) activation during maintenance. This pattern of significant results remained unchanged with inclusion of demographic and prenatal measures as covariates. Surprisingly, however, at the group level, cannabis users generally performed better than participants who reported never using cannabis (faster RT, higher accuracy). We extend previous investigations by identifying that WM associations with cannabis age of onset may be primary to PPC stimulus encoding activity, while the amount of cannabis use is associated with DLPFC maintenance processes. Poorer performance of participants who reported never using cannabis and the consistency of cannabis age of onset associations across single and repeated users limit interpretation of direct developmental effects of cannabis on WM in adulthood.

YNIMG Journal 2018 Journal Article

Incentives facilitate developmental improvement in inhibitory control by modulating control-related networks

Michael N. Hallquist
Charles F. Geier
Beatriz Luna

Adolescence is a period of heightened sensitivity to incentives and relatively weak cognitive control, which may contribute to risky behaviors. Studies of brain activity have generally identified greater activation of the ventral striatum to rewards and less activation of prefrontal regions during control tasks in adolescents compared to adults. Little is known, however, about age-related changes in the functional brain networks underlying incentive processing and cognitive control. This cross-sectional study characterized the effects of incentives on inhibitory control during an oculomotor task using whole-brain functional connectivity analyses. During an fMRI scan, one hundred forty typically developing individuals completed an incentivized antisaccade task consisting of incentive cue, preparation, and response phases. We found that task modulation of control networks increased gradually from childhood to adulthood, whereas a network including ventral striatum and ventromedial prefrontal cortex displayed an adolescent-specific peak in response to the receipt of outcomes, consistent with dual-systems models. Notably, however, greater modulation of salience and motor networks during the preparation phase mediated age-related improvements in antisaccade accuracy, whereas adolescent enhancement of value-related circuitry did not. Relative to neutral cues, both reward and loss cues enhanced task-related connectivity of the salience network when preparing to inhibit a saccade. Altogether, our findings suggest that incentives facilitate inhibitory control by enhancing the salience of one's responses and that over development, the recruitment of functional networks involved in saliency and motor preparation supports better performance.

YNIMG Journal 2017 Journal Article

Modulation of reward-related neural activation on sensation seeking across development

Samuel W. Hawes
Rajpreet Chahal
Michael N. Hallquist
David J. Paulsen
Charles F. Geier
Beatriz Luna

Sensation seeking is a personality construct associated with an increased propensity for engaging in risk-taking. Associations with deleterious outcomes ranging from mental health impairments to increased mortality rates highlight important public health concerns related to this construct. Although some have suggested that increased neural responsivity to reward within the ventral striatum (e. g. , nucleus accumbens) may drive sensation seeking behaviors, few studies have examined the neural mechanisms associated with stable individual differences in sensation seeking across development. To address this issue, the current study used functional magnetic resonance imaging to examine the association between neural responding to reward and stable patterns of sensation seeking across a three-year follow-up period among healthy adolescents and young adults (N = 139). Results indicated that during early adolescence (~ages 10–12), increased reactivity to reward within the nucleus accumbens (NAcc) was associated with lower levels of sensation seeking across a three-year follow-up. In middle adolescence (~ages 12–16), there was no evidence of a relationship between NAcc reactivity and sensation seeking. However, during the transition from late adolescence into adulthood (~ages 17–25), heightened reward-related reactivity in the NAcc was linked to increased sensation seeking. Findings suggest that the neural mechanisms underlying individual differences in trait-like levels of sensation seeking change from early to late adolescence.

YNIMG Journal 2017 Journal Article

Protracted development of executive and mnemonic brain systems underlying working memory in adolescence: A longitudinal fMRI study

Daniel J. Simmonds
Michael N. Hallquist
Beatriz Luna

Working memory (WM), the ability to hold information on-line to guide planned behavior, improves through adolescence in parallel with continued maturation of critical brain systems supporting cognitive control. Initial developmental neuroimaging studies with one or two timepoints have provided important though varied results limiting our understanding of which and how neural systems change during this transition into mature WM. In this study, we leverage functional magnetic resonance imaging (fMRI) longitudinal data spanning up to 9 years in 129 normally developing individuals to identify which systems demonstrate growth changes that accompany improvements in WM performance. We used a memory guided saccade task that allowed us to probe encoding, pure maintenance, and retrieval neural processes of WM. Consistent with prior research, we found that WM performance continued to improve into the early 20's. fMRI region of interest (ROI) analyses revealed developmental (1) increases in sensorimotor-related (encoding/retrieval) activity in visual cortex from childhood through early adulthood that were associated with WM accuracy and (2) decreases in sustained (maintenance) activity in executive regions from childhood through mid-adolescence that were associated with response latency in childhood and early adolescence. Together these results provide compelling evidence that underlying the maturation of WM is a transition from reliance on executive systems to specialized regions related to the domain of mnemonic requirements of the task leading to optimal performance.

YNIMG Journal 2016 Journal Article

Frontal preparatory neural oscillations associated with cognitive control: A developmental study comparing young adults and adolescents

Kai Hwang
Avniel S. Ghuman
Dara S. Manoach
Stephanie R. Jones
Beatriz Luna

Functional magnetic resonance imaging (fMRI) studies suggest that age-related changes in the frontal cortex may underlie developmental improvements in cognitive control. In the present study we used magnetoencephalography (MEG) to identify frontal oscillatory neurodynamics that support age-related improvements in cognitive control during adolescence. We characterized the differences in neural oscillations in adolescents and adults during the preparation to suppress a prepotent saccade (antisaccade trials—AS) compared to preparing to generate a more automatic saccade (prosaccade trials—PS). We found that for adults, AS were associated with increased beta-band (16–38Hz) power in the dorsal lateral prefrontal cortex (DLPFC), enhanced alpha- to low beta-band (10–18Hz) power in the frontal eye field (FEF) that predicted performance, and increased cross-frequency alpha-beta (10–26Hz) amplitude coupling between the DLPFC and the FEF. Developmental comparisons between adults and adolescents revealed similar engagement of DLPFC beta-band power but weaker FEF alpha-band power, and lower cross-frequency coupling between the DLPFC and the FEF in adolescents. These results suggest that lateral prefrontal neural activity associated with cognitive control is adult-like by adolescence; the development of cognitive control from adolescence to adulthood is instead associated with increases in frontal connectivity and strengthening of inhibition signaling for suppressing task-incompatible processes.

YNIMG Journal 2014 Journal Article

Developmental stages and sex differences of white matter and behavioral development through adolescence: A longitudinal diffusion tensor imaging (DTI) study

Daniel J. Simmonds
Michael N. Hallquist
Miya Asato
Beatriz Luna

White matter (WM) continues to mature through adolescence in parallel with gains in cognitive ability. To date, developmental changes in human WM microstructure have been inferred using analyses of cross-sectional or two time-point follow-up studies, limiting our understanding of individual developmental trajectories. The aims of the present longitudinal study were to characterize the timing of WM growth and investigate how sex and behavior are associated with different developmental trajectories. We utilized diffusion tensor imaging (DTI) in 128 individuals aged 8–28, who received annual scans for up to 5years and completed motor and cognitive tasks. Flexible nonlinear growth curves indicated a hierarchical pattern of WM development. By late childhood, posterior cortical–subcortical connections were similar to adults. During adolescence, WM microstructure reached adult levels, including frontocortical, frontosubcortical and cerebellar connections. Later to mature in adulthood were major corticolimbic association tracts and connections at terminal gray matter sites in cortical and basal ganglia regions. These patterns may reflect adolescent maturation of frontal connectivity supporting cognitive abilities, particularly the protracted refinement of corticolimbic connectivity underlying cognition–emotion interactions. Sex and behavior also played a large role. Males showed continuous WM growth from childhood through early adulthood, whereas females mainly showed growth during mid-adolescence. Further, earlier WM growth in adolescence was associated with faster and more efficient responding and better inhibitory control whereas later growth in adulthood was associated with poorer performance, suggesting that the timing of WM growth is important for cognitive development.

YNIMG Journal 2014 Journal Article

fNIRS evidence of prefrontal regulation of frustration in early childhood

Susan B. Perlman
Beatriz Luna
Tyler C. Hein
Theodore J. Huppert

The experience of frustration is common in early childhood, yet some children seem to possess a lower tolerance for frustration than others. Characterizing the biological mechanisms underlying a wide range of frustration tolerance observed in early childhood may inform maladaptive behavior and psychopathology that is associated with this construct. The goal of this study was to measure prefrontal correlates of frustration in 3–5-year-old children, who are not readily adaptable for typical neuroimaging approaches, using functional near infrared spectroscopy (fNIRS). fNIRS of frontal regions were measured as frustration was induced in children through a computer game where a desired and expected prize was “stolen” by an animated dog. A fNIRS general linear model (GLM) was used to quantify the correlation of brain regions with the task and identify areas that were statistically different between the winning and frustrating test conditions. A second-level voxel-based ANOVA analysis was then used to correlate the amplitude of each individual's brain activation with measure of parent-reported frustration. Experimental results indicated increased activity in the middle prefrontal cortex during winning of a desired prize, while lateral prefrontal cortex activity increased during frustration. Further, activity increase in lateral prefrontal cortex during frustration correlated positively with parent-reported frustration tolerance. These findings point to the role of the lateral prefrontal cortex as a potential region supporting the regulation of emotion during frustration.

YNIMG Journal 2013 Journal Article

The nuisance of nuisance regression: Spectral misspecification in a common approach to resting-state fMRI preprocessing reintroduces noise and obscures functional connectivity

Michael N. Hallquist
Kai Hwang
Beatriz Luna

Recent resting-state functional connectivity fMRI (RS-fcMRI) research has demonstrated that head motion during fMRI acquisition systematically influences connectivity estimates despite bandpass filtering and nuisance regression, which are intended to reduce such nuisance variability. We provide evidence that the effects of head motion and other nuisance signals are poorly controlled when the fMRI time series are bandpass-filtered but the regressors are unfiltered, resulting in the inadvertent reintroduction of nuisance-related variation into frequencies previously suppressed by the bandpass filter, as well as suboptimal correction for noise signals in the frequencies of interest. This is important because many RS-fcMRI studies, including some focusing on motion-related artifacts, have applied this approach. In two cohorts of individuals (n =117 and 22) who completed resting-state fMRI scans, we found that the bandpass–regress approach consistently overestimated functional connectivity across the brain, typically on the order of r =. 10–. 35, relative to a simultaneous bandpass filtering and nuisance regression approach. Inflated correlations under the bandpass–regress approach were associated with head motion and cardiac artifacts. Furthermore, distance-related differences in the association of head motion and connectivity estimates were much weaker for the simultaneous filtering approach. We recommend that future RS-fcMRI studies ensure that the frequencies of nuisance regressors and fMRI data match prior to nuisance regression, and we advocate a simultaneous bandpass filtering and nuisance regression strategy that better controls nuisance-related variability.

YNIMG Journal 2007 Journal Article

Circuitry underlying temporally extended spatial working memory

Charles F. Geier
Krista E. Garver
Beatriz Luna

Extended maintenance delays decrease the accuracy of information stored in spatial working memory. In order to elucidate the network underlying sustained spatial working memory, 16 subjects were scanned using fast event-related fMRI as they performed an oculomotor delayed response task containing trials with “short” (2. 5 s) or “long” (10 s) delay periods. Multiple cortical and subcortical regions were common to both delay trial types indicating core task regions. Three patterns of activity were found in a subset of core regions that reflect underlying processes: maintenance-related (e. g. , left FEF, right supramarginal gyrus (SMG)), response planning-related (e. g. , right FEF, SEF), and motor response-related (e. g. , lateral cerebellum (declive)) activation. Several regions were more active during long than short delay trials, including multiple sites in DLPFC (BA 9, 46), indicating a circuitry dynamically recruited to support sustained working memory. Our results suggest that specialized brain processes support extended periods of working memory.

YNIMG Journal 2007 Journal Article

fMRI studies of eye movement control: Investigating the interaction of cognitive and sensorimotor brain systems

John A. Sweeney
Beatriz Luna
Sarah K. Keedy
Jennifer E. McDowell
Brett A. Clementz

Functional neuroimaging studies of eye movement control have been a useful approach for investigating the interaction of cognitive and sensorimotor brain systems. Building on unit recording studies of behaving nonhuman primates and clinical studies of patients with a focal brain lesion, functional neuroimaging studies have elucidated a pattern of hierarchical organization through which prefrontal and premotor systems interact with sensorimotor systems to support context-dependent adaptive behavior. Studies of antisaccades, memory-guided saccades, and predictive saccades have helped clarify how cognitive brain systems support contextually guided and internally generated action. The use of cognitive and sensorimotor eye movement paradigms is being used to develop a better understanding of life span changes in neurocognitive systems from childhood to late life, and about behavioral and systems-level brain abnormalities in neuropsychiatric disorders.

YNIMG Journal 2002 Journal Article

Combining Brains: A Survey of Methods for Statistical Pooling of Information

Nicole A. Lazar
Beatriz Luna
John A. Sweeney
William F. Eddy

More than one subject is scanned in a typical functional brain imaging experiment. How can the scientist make best use of the acquired data to map the specific areas of the brain that become active during the performance of different tasks? It is clear that we can gain both scientific and statistical power by pooling the images from multiple subjects; furthermore, for the comparison of groups of subjects (clinical patients vs healthy controls, children of different ages, left-handed people vs right-handed people, as just some examples), it is essential to have a “group map” to represent each population and to form the basis of a statistical test. While the importance of combining images for these purposes has been recognized, there has not been an organized attempt on the part of neuroscientists to understand the different statistical approaches to this problem, which have various strengths and weaknesses. In this paper we review some popular methods for combining information, and demonstrate the surveyed techniques on a sample data set. Given a combination of brain images, the researcher needs to interpret the result and decide on areas of activation; the question of thresholding is critical here and is also explored.

YNIMG Journal 2001 Journal Article

Maturation of Widely Distributed Brain Function Subserves Cognitive Development

Beatriz Luna
Keith R. Thulborn
Douglas P. Munoz
Elisha P. Merriam
Krista E. Garver
Nancy J. Minshew
Matcheri S. Keshavan
Christopher R. Genovese

Cognitive and brain maturational changes continue throughout late childhood and adolescence. During this time, increasing cognitive control over behavior enhances the voluntary suppression of reflexive/impulsive response tendencies. Recently, with the advent of functional MRI, it has become possible to characterize changes in brain activity during cognitive development. In order to investigate the cognitive and brain maturation subserving the ability to voluntarily suppress context-inappropriate behavior, we tested 8–30 year olds in an oculomotor response–suppression task. Behavioral results indicated that adult-like ability to inhibit prepotent responses matured gradually through childhood and adolescence. Functional MRI results indicated that brain activation in frontal, parietal, striatal, and thalamic regions increased progressively from childhood to adulthood. Prefrontal cortex was more active in adolescents than in children or adults; adults demonstrated greater activation in the lateral cerebellum than younger subjects. These results suggest that efficient top-down modulation of reflexive acts may not be fully developed until adulthood and provide evidence that maturation of function across widely distributed brain regions lays the groundwork for enhanced voluntary control of behavior during cognitive development.

YNIMG Journal 2001 Journal Article

Stimulus–Response Incompatibility Activates Cortex Proximate to Three Eye Fields

Elisha P. Merriam
Carol L. Colby
Keith R. Thulborn
Beatriz Luna
Carl R. Olson
John A. Sweeney

We used functional magnetic resonance imaging (fMRI) to investigate cortical activation during the performance of three oculomotor tasks that impose increasing levels of cognitive demand. (1) In a visually guided saccade (VGS) task, subjects made saccades to flashed targets. (2) In a compatible task, subjects made leftward and rightward saccades in response to foveal presentation of the uppercase words “LEFT” or “RIGHT. ” (3) In a mixed task, subjects made rightward saccades in response to the lowercase word “left” and leftward saccades in response to the lowercase word “right” on incompatible trials (60%). The remaining 40% of trials required compatible responses to uppercase words. The VGS and compatible tasks, when compared to fixation, activated the three cortical eye fields: the supplementary eye field (SEF), the frontal eye field (FEF), and the parietal eye field (PEF). The mixed task, when compared to the compatible task, activated three additional cortical regions proximate to the three eye fields: (1) rostral to the SEF in medial frontal cortex; (2) rostral to the FEF in dorsolateral prefrontal cortex (DLPFC); (3) rostral and lateral to the PEF in posterior parietal cortex. These areas may contribute to the suppression of prepotent responses and in holding novel visuomotor associations in working memory.