Biomedical subjects

Beatriz Luna

Publications and source records attributed to Beatriz Luna.

16 recordsLinked to original sources

PubMed2007

Spatial working memory deficits in autism.

Previous studies have reported working memory deficits in autism, but this finding has been inconsistent. One possibility is that deficits in this domain may be present only when working memory load exceeds some limited capacity. High-functioning individuals with autism performed the CANTAB computerized test of spatial working memory. Individuals with autism made more errors than a matched group of typically developing controls on this task, and were less likely to consistently use a specific organized search strategy to complete the task. Overall, these results demonstrate reduced spatial working memory abilities in autism, and extend previous findings by demonstrating that these deficits are significant when tasks impose heavier demands on working memory.

Adolescent↗

PubMed2006

Cognitive processes in the development of TOL performance.

Components of executive function continue to develop through adolescence. There is limited knowledge of how these cognitive components impact complex cognitive function requiring their integration. This study examines the development of response planning, a complex cognitive function, and the contributions of selected cognitive processes, including speed of processing, response inhibition, and working memory to its development. We tested 100 healthy 8-30 year old individuals with a computerized version to the Tower of London (TOL) task and cognitive oculomotor tests including the visually guided saccade, oculomotor delayed response, and antisaccade tasks. Speed of processing, response inhibition, working memory, and TOL performance all demonstrated maturation in adolescence. While all processes were correlated with the development of TOL performance, antisaccade performance showed the strongest association indicating an important role for response inhibition in planning. These results indicate that the development of converging cognitive processes in adolescence, including response inhibition and working memory, support response planning and may serve as a model for the development of performance in other complex problem solving tasks.

Adolescent↗

PubMed2006

Maturation of executive function in autism.

BACKGROUND: Executive dysfunction has been reported at different ages in autism. It is not clear however, when this impairment emerges or how its expression is affected by development. METHODS: 61 non-mentally retarded autism participants (AUT) and 61 age, gender, and IQ matched typically developing participants (CON) were assessed with two oculomotor executive function tasks, the oculomotor delayed response task (ODR) and the antisaccade task (AS), as well as a visually-guided saccade sensorimotor task (VGS). RESULTS: The AUT group demonstrated impairments in response inhibition and spatial working memory at all ages tested. Developmental improvements in speed of sensorimotor processing and voluntary response inhibition were similar in both groups indicating sparing of some attentional control of behavior. Developmental progression in the speed of initiating a cognitive plan and maintaining information on line over time, however, was impaired in the AUT group indicating abnormal development of working memory. CONCLUSIONS: These results indicate that while executive dysfunction is present throughout development, there is evidence for both typical and atypical developmental progression of executive functions in autism. The plasticity suggested by the developmental improvements may have implications regarding appropriate developmental epochs and types of interventions aimed at enhancing cognitive capacities in individuals with autism.

Adolescent↗

PubMed2006

Configural processing in autism and its relationship to face processing.

Studies of the perceptual performance of individuals with autism have focused, to a large extent, on two domains of visual behavior, one associated with face processing and the other associated with global or holistic processing. Whether autistic individuals differ from neurotypical individuals in these domains is debatable and, moreover, the relationship between the behaviors in these two domains remains unclear. We first compared the face processing ability of 14 adult individuals with autism with that of neurotypical controls and showed that the autistic individuals were slowed in their speed of face discrimination. We then showed that the two groups differed in their ability to derive the global whole in two different tasks, one using hierarchical compound letters and the other using a microgenetic primed matching task with geometric shapes, with the autistic group showing a bias in favor of local information. A significant correlation was also observed between performance on the face task and the configural tasks. We then confirmed the prediction that the ability to derive the global whole is not only critical for faces but also for other objects as well, as the autistic individuals performed more slowly than the control group in discriminating between objects. Taken together, the results suggest that the bias for local processing seen in autistic individuals might have an adverse impact on their ability to process faces and objects.

Adult↗

PubMed2006

Brain basis of developmental change in visuospatial working memory.

Although brain changes associated with the acquisition of cognitive abilities in early childhood involve increasing localized specialization, little is known about the brain changes associated with the refinement of existing cognitive abilities that reach maturity in adolescence. The goal of this study was to investigate developmental changes in functional brain circuitry that support improvements in visuospatial working memory from childhood to adulthood. We tested thirty 8- to 47-year-olds in an oculomotor delayed response task. Developmental transitions in brain circuitry included both quantitative changes in the recruitment of necessary working memory regions and qualitative changes in the specific regions recruited into the functional working memory circuitry. Children recruited limited activation from core working memory regions (dorsal lateral prefrontal cortex [DLPFC] and parietal regions) and relied primarily on ventromedial regions (caudate nucleus and anterior insula). With adolescence emerged a more diffuse network (DLPFC, anterior cingulate, posterior parietal, anterior insula) that included the functional integration of premotor response preparation and execution circuitry. Finally, adults recruited the most specialized network of localized regions together with additional performance-enhancing regions, including left-lateralized DLPFC, ventrolateral prefrontal cortex, and supramarginal gyrus. These results suggest that the maturation of adult-level cognition involves a combination of increasing localization within necessary regions and their integration with performance-enhancing regions.

Adolescent↗

PubMed2005

Oculomotor studies of cerebellar function in autism.

Histopathological, neuroimaging and genetic findings indicate cerebellar abnormalities in autism, but the extent of neurophysiological dysfunction associated with those findings has not been systematically examined. Suppression of intrusive saccades (square wave jerks) and the ability to sustain eccentric gaze, two phenomena requiring intact cerebellar function, were examined in 52 high-functioning individuals with autism and 52 age- and IQ-matched healthy subjects during visual fixation of static central and peripheral targets. Rates of intrusive saccades were not increased in autism during visual fixation, and foveopetal ocular drift was also not increased when subjects held an eccentric gaze. The absence of gross disturbances of visual fixation associated with cerebellar disease in individuals with autism, such as increased square wave jerk rates and foveopetal drift when holding eccentric gaze, indicates that the functional integrity of cerebellar--brainstem networks devoted to oculomotor control is preserved in autism despite reported anatomic variations. However, increased amplitude of intrusive saccades and reduced latency of target refixation after intrusive saccades were observed in individuals with autism, especially when subjects maintained fixation of remembered target locations without sensory guidance. The atypical metrics of intrusive saccades that were observed may be attributable to faulty functional connectivity in cortico-cerebellar networks.

Adolescent↗

PubMed2005

Impaired oculomotor response inhibition in children of alcoholics: The role of attention deficit hyperactivity disorder.

OBJECTIVE: The aim of the project was to determine whether children at high risk for alcohol use disorder (AUD) are impaired at performing oculomotor response inhibition tasks sensitive to detecting prefrontal cortex dysfunction. METHODS: Three antisaccade tasks were administered to 67 10-12-year-old children having fathers with AUD and 12 children whose fathers had no psychiatric disorder. RESULTS: Children of AUD+ fathers performed similar to children of AUD- fathers on measures of response latency and gain to target. Peak velocity discriminated the two groups on only one task. Children of AUD+ fathers exhibited a higher rate of prosaccade errors on the most difficult antisaccade task. Within the AUD+ group of men, offspring who qualified for attention deficit hyperactivity disorder (ADHD; N = 13) exhibited more response suppression errors than children without ADHD on two of three tasks. No differences were observed between children without ADHD whose fathers either qualified for AUD+ or had no psychiatric disorder. CONCLUSION: Inhibiting a response to a prepotent stimulus in children of AUD+ fathers is circumscribed to ADHD youths. These findings suggest that frontal-striatal mechanisms may underlie the risk for AUD among ADHD children.

Alcoholism↗

PubMed2004

Pursuit eye movement deficits in autism.

Oculomotor studies provide a novel strategy for evaluating the functional integrity of multiple brain systems and cognitive processes in autism. The current study compared pursuit eye movements of 60 high-functioning individuals with autism and 94 intelligence quotient, age and gender matched healthy individuals using ramp and oscillating target tasks. Individuals with autism had normal pursuit latency, but reduced closed-loop pursuit gain when tracking both oscillating and ramp targets. This closed-loop deficit was similar for leftward and rightward pursuit, but the difference between individuals with autism and their age-matched peers was more apparent after mid-adolescence, suggesting reduced maturational achievement of the pursuit system in autism. Individuals with autism also had lower open-loop pursuit gain (initial 100 ms of pursuit) and less accurate initial catch-up saccades during a foveofugal step-ramp task, but these deficits were only seen when targets moved into the right visual field. Pursuit performance in both open- and closed-loop phases was correlated with manual praxis in individuals with autism. Bilateral disturbances in the ability to use internally generated extraretinal signals for closed-loop pursuit implicate frontostriatal or cerebellar circuitry. The hemifield specific deficit in open-loop pursuit demonstrates a lateralized disturbance in the left extrastriate areas that extract visual motion information, or in the transfer of visual motion information to the sensorimotor areas that transform visual information into appropriate oculomotor commands.

Adolescent↗

PubMed2004

Increased activation of anterior paralimbic and executive cortex from waking to rapid eye movement sleep in depression.

BACKGROUND: Depression is associated with sleep disturbances, including alterations in rapid eye movement (REM) sleep, that may relate to the neurobiology of the disorder. Given that REM sleep activates limbic and anterior paralimbic cortex and that depressed patients demonstrate increases in electroencephalographic sleep measures of REM, we hypothesized greater activation of these structures during waking to REM sleep in depressed patients. DESIGN: Subjects completed electroencephalographic sleep and regional cerebral glucose metabolism assessments during both waking and REM sleep using [(18)F]fluoro-2-deoxy-D-glucose positron emission tomography. SETTING: Patients and healthy subjects recruited from the general community to participate in a research study of depression at an academic medical center. Patients Twenty-four unmedicated patients who met the Structured Clinical Interview for DSM-IV criteria for current major depression and who had a score of 15 or higher on a 17-item Hamilton Rating Scale for Depression; 14 medically healthy subjects of comparable age and sex who were free of mental disorders. MAIN OUTCOME MEASURES: Electroencephalographic sleep, semiquantitative and relative regional cerebral metabolism during waking and REM sleep. RESULTS: Depressed patients showed greater REM sleep percentages. While both healthy and depressed patients activated anterior paralimbic structures from waking to REM sleep, the spatial extent of this activation was greater in the depressed patients. Additionally, depressed patients showed greater activation in bilateral dorsolateral prefrontal, left premotor, primary sensorimotor, and left parietal cortices, as well as in the midbrain reticular formation. CONCLUSIONS: Increased anterior paralimbic activation from waking to REM sleep may be related to affective dysregulation in depressed patients. Increased activation of executive cortex may be related to a cognitive dysregulation. These results suggest that altered function of limbic/anterior paralimbic and prefrontal circuits in depression is accentuated during the REM sleep state. The characteristic sleep disturbances of depression may reflect this dysregulation.

Adult↗

PubMed2004

Algebra and the adolescent brain.

New fMRI evidence suggests that adolescents could be at an advantage for learning algebra compared with adults. Qin and colleagues present findings indicating that after several days of practice adolescents rely on prefrontal regions to support the retrieval of algebraic rules to solve equations, as do adults. Unlike adults, however, after practice adolescents decrease their reliance on parietal regions, which assist in the transformation of the equations, suggesting an enhanced ability for learning algebra. These findings are discussed with regard to adolescent brain maturation.

Adolescent↗

PubMed2004

Eye movements in neurodevelopmental disorders.

PURPOSE OF REVIEW: The aim of this paper is to review the literature on eye-movement abnormalities associated with neurodevelopmental disorders. Eye-movement testing is a non-invasive quantitative approach for evaluating brain systems across the age spectrum. It thus provides a promising methodology for characterizing and documenting maturational abnormalities in brain systems associated with neurodevelopmental disorders. RECENT FINDINGS: Recent oculomotor studies have made significant contributions to the understanding of neurodevelopmental disorders, most notably in autism, attention-deficit/hyperactivity disorder, and Tourette's syndrome. Notably different patterns of deficits have been found in these disorders and have helped to clarify their pathophysiology. SUMMARY: Eye-movement studies have begun to serve as a useful approach for studying cognitive and neurophysiological aspects of neurodevelopmental disorders. They also have potential as a strategy for establishing quantitative endophenotypes for genetic research, and for monitoring beneficial and adverse effects of pharmacotherapies. Studies are needed that involve larger patient populations, longitudinal characterization of developmental failures, patients free from central nervous system-active medications, and that use functional imaging, as patients perform eye-movement tasks, for direct identification of clinically relevant abnormalities in brain systems.

Attention Deficit Disorder with Hyperactivity↗

PubMed2004

The emergence of collaborative brain function: FMRI studies of the development of response inhibition.

Adolescence marks the beginning of adult-level cognitive control of behavior supported by the brain maturation processes of synaptic pruning and myelination. Cognitive development studies on adolescence indicate that this period is characterized by improvements in the performance of existing abilities including speed and capacity of information processing and the ability to have consistent cognitive control of behavior. Although adolescents can behave at adult levels in some ways, brain imaging studies indicate that the functional organization of brain systems that support higher-cognitive processes are not fully mature. Synaptic pruning allows for more efficient local computations, enhancing the ability of discrete brain regions to support high-level cognitive control of behavior including working memory. Myelination increases the speed of neuronal transmission supporting the collaboration of a widely distributed circuitry, integrating regions that support top-down cognitive control of behavior. Functional brain imaging methods allow for the characterization of the relationship between cognitive development and brain maturation as we can map progressions in the establishment of distributed brain circuitry and its relation to enhanced cognitive control of behavior. We present a review on the maturation (as distinct from "development" in emphasizing the transition to maturity and stabilization) of response inhibition, brain structure, and brain function through adolescence. We also propose a model for brain-behavior maturation that allows for the qualitative changes in cognitive processes that occur during adolescence.

Adolescent↗

PubMed2002

Combining brains: a survey of methods for statistical pooling of information.

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.

Adult↗

PubMed2002

A preliminary functional magnetic resonance imaging study in offspring of schizophrenic parents.

Studies of high-risk offspring (HR) of schizophrenic patients have found abnormalities in attention, working memory and executive functions, suggesting impaired integrity of the prefrontal cortex and related brain regions. The authors conducted a preliminary high-field (3 T) functional magnetic resonance imaging (fMRI) study to assess performance and activation during a memory-guided saccade (MGS) task, which measures spatial working memory. HR subjects showed significant decreases in fMRI-measured activation in the dorsolateral prefrontal cortex (Brodmann's areas 8 and 9/46) and the inferior parietal cortex (Brodmann's area 40) compared to age- and sex-matched healthy controls (HC). Abnormal functional integrity of prefrontal and parietal regions of the heteromodal association cortical (HAC) regions in subjects at genetic risk for schizophrenia is consistent with findings observed in adults with the illness [Callicott et al., Cereb. Cortex 10 (2000) 1078; Manoach et al., Biol. Psychiatry 48 (2000) 99.]. These abnormalities need to be prospectively investigated in nonpsychotic individuals at risk for schizophrenia in order to determine their predictive value for eventual emergence of schizophrenia or related disorders.

Adolescent↗

PubMed2002

Pursuit and saccadic eye movement subregions in human frontal eye field: a high-resolution fMRI investigation.

Recent positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies in humans have localized the frontal eye field (FEF) to the precentral sulcus (PCS). In macaque monkeys, low-threshold microstimulation and single unit recording studies have located a saccadic subregion of FEF in a restricted area along the anterior wall of the arcuate sulcus and a pursuit subregion located deeper in the sulcus close to the fundus. The functional organization and anatomical location of these two FEF subregions are still to be defined in humans. In the present study, we used fMRI with high spatial resolution image acquisition at 3.0 Tesla to map the saccade- and pursuit-related areas of FEF within the two walls of the PCS in 11 subjects. We localized the saccade-related area to the upper portion of the anterior wall of the precentral sulcus and the pursuit-related area to a deeper region along the anterior wall, extending in some subjects to the fundus or deep posterior wall. These findings localize distinct pursuit and saccadic subregions of FEF in humans and demonstrate a high degree of homology in the organization of these FEF subregions in the human and the macaque monkey.

Adult↗

PubMedDate not supplied

Maturation of cognitive processes from late childhood to adulthood.

To characterize cognitive maturation through adolescence, processing speed, voluntary response suppression, and spatial working memory were measured in 8- to 30-year-old (N = 245) healthy participants using oculomotor tasks. Development progressed with a steep initial improvement in performance followed by stabilization in adolescence. Adult-level mature performance began at approximately 15, 14, and 19 years of age for processing speed, response inhibition, and working memory, respectively. Although processes developed independently, processing speed influenced the development of working memory whereas the development of response suppression and working memory were interdependent. These results indicate that processing speed, voluntary response suppression, and working memory mature through late childhood and into adolescence. How brain maturation specific to adolescence may support cognitive maturation is discussed.

Adolescent↗