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Daniel S. O'Leary

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.

11 papers
1 author row

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11

YNIMG Journal 2016 Journal Article

The Function Biomedical Informatics Research Network Data Repository

  • David B. Keator
  • Theo G.M. van Erp
  • Jessica A. Turner
  • Gary H. Glover
  • Bryon A. Mueller
  • Thomas T. Liu
  • James T. Voyvodic
  • Jerod Rasmussen

The Function Biomedical Informatics Research Network (FBIRN) developed methods and tools for conducting multi-scanner functional magnetic resonance imaging (fMRI) studies. Method and tool development were based on two major goals: 1) to assess the major sources of variation in fMRI studies conducted across scanners, including instrumentation, acquisition protocols, challenge tasks, and analysis methods, and 2) to provide a distributed network infrastructure and an associated federated database to host and query large, multi-site, fMRI and clinical data sets. In the process of achieving these goals the FBIRN test bed generated several multi-scanner brain imaging data sets to be shared with the wider scientific community via the BIRN Data Repository (BDR). The FBIRN Phase 1 data set consists of a traveling subject study of 5 healthy subjects, each scanned on 10 different 1. 5 to 4T scanners. The FBIRN Phase 2 and Phase 3 data sets consist of subjects with schizophrenia or schizoaffective disorder along with healthy comparison subjects scanned at multiple sites. In this paper, we provide concise descriptions of FBIRN's multi-scanner brain imaging data sets and details about the BIRN Data Repository instance of the Human Imaging Database (HID) used to publicly share the data.

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YNIMG Journal 2000 Journal Article

An MRI-Based Parcellation Method for the Temporal Lobe

  • Jae-Jin Kim
  • Benedicto Crespo-Facorro
  • Nancy C. Andreasen
  • Daniel S. O'Leary
  • Baiquan Zhang
  • Gregory Harris
  • Vincent A. Magnotta

The temporal lobe has long been a focus of attention with regard to the underlying pathology of several major psychiatric illnesses. Previous postmortem and imaging studies describing regional volume reductions or perfusion defects in temporal subregions have shown inconsistent findings, which are in part due to differences in the definition of the subregions and the methodology of measurement. The development of precise reproducible parcellation systems on magnetic resonance images may help improve uniformity of results in volumetric MR studies and unravel the complex activation patterns seen in functional neuroimaging studies. The present study describes detailed guidelines for the parcellation of the temporal neocortex. It parcels the entire temporal neocortex into 16 subregions: temporal pole, heschl's gyrus, planum temporale, planum polare, superior temporal gyrus (rostral and caudal), middle temporal gyrus (rostral, intermediate, and caudal), inferior temporal gyrus (rostral, intermediate, and caudal), occipitotemporal gyrus (rostral and caudal), and parahippocampal gyrus (rostral and caudal). Based upon topographic landmarks of individual sulci, every subregion was consecutively traced on a set of serial coronal slices. In spite of the huge variability of sulcal topography, the sulcal landmarks could be identified reliably due to the simultaneous display of three orthogonal (transaxial, coronal, and sagittal) planes, triangulated gray matter isosurface, and a 3-D-rendered image. The reliability study showed that the temporal neocortex could be parceled successfully and reliably; intraclass correlation coefficient for each subregion ranged from 0. 62 to 0. 99. Ultimately, this method will permit us to detect subtle morphometric impairments or to find abnormal patterns of functional activation in the temporal subregions that might reflect underlying neuropathological processes in psychiatric illnesses such as schizophrenia.

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YNIMG Journal 1999 Journal Article

Human Frontal Cortex: An MRI-Based Parcellation Method

  • Benedicto Crespo-Facorro
  • Jae-Jin Kim
  • Nancy C. Andreasen
  • Daniel S. O'Leary
  • Anne K. Wiser
  • James M. Bailey
  • Gregory Harris
  • Vincent A. Magnotta

The frontal lobe is not a single anatomical and functional brain region. Several lines of research have demonstrated that particular subregions within the frontal lobe are associated with specific motor and cognitive functions in the human being. Our main purpose is to develop a magnetic resonance image (MRI)-based parcellation method of the frontal lobe that permits us to explore plausible abnormalities in functionally relevant frontal subregions in brain illnesses. We describe a procedure using MRI for subdividing the entire frontal cortex into 11 subregions: supplementary motor area (SMA), rostral anterior cingulate gyrus (r-ACiG), caudal anterior cingulate gyrus (c-ACiG), superior cingulate gyrus (SCiG), medial frontal cortex (MFC), straight gyrus (SG), orbitofrontal cortex (OFC), precentral gyrus (PCG), superior frontal gyrus (SFG), inferior frontal gyrus (IFG), and middle frontal gyrus (MFG). Our method posits to conserve the topographic uniqueness of individual brains and is based on our ability to visualize both the three-dimensional (3D) rendered brain and the three orthogonal planes simultaneously. The reliability study for gray matter volume and surface area of each subregion was performed on a set of 10 MR scans by two raters. The intraclass R coefficients for gray matter volume of each subregion ranged between 0. 86 and 0. 99. We describe here a reproducible and reliable topography-based parcellation method of the frontal lobe that will allow us to use new approaches to understand the role of particular frontal cortical subregions in schizophrenia and other brain illnesses.

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YNIMG Journal 1997 Journal Article

Factors That Influence Effect Size in15O PET Studies: A Meta-analytic Review

  • Sherri Gold
  • Stephan Arndt
  • Debra Johnson
  • Daniel S. O'Leary
  • Nancy C. Andreasen

The PET literature is growing exponentially, creating a need and an opportunity to perform a meta-analytic review consolidating the published information. This study describes the use of effect size as an index in PET studies and discusses how this measure can be used for comparing findings across studies, laboratories, and paradigms. In comparing studies across laboratories it is essential to know how the methods employed affect the results and conclusions drawn. This study also compared effect size for two different methods of tracer delivery in15O PET studies ([15O]H2O bolus injection versus inhalation of [15O]CO2), whether averaged versus single-scan conditions were used, and the data analytic strategy employed. The effect sizes observed across studies were consistently large with a median effect size of 8. 55, indicating that the phenomena investigated in15O PET studies are strong. The largest peak activation reported in a study was found to be affected by variability in sample size, data analytic strategy, and repeat versus single-scan conditions. However, the impact of these factors was not examined on smaller or less intense peaks. Minimal standards for reporting statistical results are discussed.

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YNIMG Journal 1995 Journal Article

I. PET Studies of Memory: Novel and Practiced Free Recall of Complex Narratives

  • Nancy C. Andreasen
  • Daniel S. O'Leary
  • Stephan Arndt
  • Ted Cizadlo
  • Karim Rezai
  • G.Leonard Watkins
  • Laura L.Boles Ponto
  • Richard D. Hichwa

Positron Emission Tomography (PET) with the tracer H2 15O was used to measure regional cerebral blood flow in 13 healthy volunteers during two experimental memory tasks, one of which was well-practiced and the other of which was novel. The materials used for the memory tasks consisted of two complex narratives (Story A and Story B from the Wechsler Memory Scale). Natural language materials were chosen because they similate experimentally the natural learning situation and permit study of the neural mechanisms by which recall memory becomes more fluid, automatic, or "rote. " One week before the PET study, subjects were trained to perfect recall of Story A, while they were exposed to Story B only 60s prior to PET data acquisition. Despite the substantial differences in level of familiarity (and in free recall performance), patterns of activation were quite similar; activations presumed to reflect recall in both tasks included frontal, inferior temporal, thalamic, anterior cingulate, and cerebellar regions. Many regions were smaller during recall of the familiar story, however, presumably reflecting greater neural efficiency due to practice. In addition, the novel task activated an additional left frontal region that is presumed to reflect more active encoding. The similarity and multiplicity of the activations in the two tasks suggest that the brain uses a multinodal general network for memory tasks such as free recall, while the differences suggest that some nodes in the network may be used for specific components of memory such as encoding and retrieval.

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YNIMG Journal 1995 Journal Article

II. PET Studies of Memory: Novel versus Practiced Free Recall of Word Lists

  • Nancy C. Andreasen
  • Daniel S. O'Leary
  • Ted Cizadlo
  • Stephan Arndt
  • Karim Rezai
  • G.Leonard Watkins
  • Laura L.Boles Ponto
  • Richard D. Hichwa

Positron emission tomography (PET) with the tracer Ha2 15O was used to measure regional cerebral blood flow in 13 healthy volunteers while they engaged in free recall of 15-item word lists from the Rey Auditory Verbal Learning task. The study was designed so that recall of well-practiced versus novel material could be compared. One week before the PET study, subjects were trained to perfect recall of List A, while they were exposed to list B only 60s prior to PET data acquisition. As in the companion study of free recall of complex narratives, we observed that practice tended to decrease the size of activations in regions involved in the memory component of the task; we also observed that the novel recall task produced greater activation in left frontal regions, probably due to active encoding. A commonality of other regions observed in this pair of studies, as well as other studies of memory in the literature, suggests that the human brain may contain a distributed multinodal general memory system. Nodes on this network include the frontal, parietal, and temporal cortices, the thalamus, the anterior and posterior cingulate, the precuneus, and the cerebellum. There appears to be a commonality of components across tasks (e. g. , retrieval, encoding) that is independent of content, as well as differentiation of some components that may be content-specific or task-specific. In addition, these results support a significant role for the cerebellum in cognitive functions such as memory.

Details DOI
v2026.09.13