Iowa

Mental Health Clinical Research Center

Department of Neurology

Department of Psychiatry Administration

Department of Radiology

Michigan

Department of Neurology

Department of Psychiatry

University of Pennsylvania

Authors

O'Leary DS. Andreasen NC. Hurtig RR. Kesler ML. Rogers M. Arndt S.

Cizadlo T. Watkins GL. Ponto LL.

Kirchner PT. Hichwa RD.

Institution

Mental Health Clinical Research Center, University of Iowa Hospitals and Clinics, Iowa City, USA.

Title

Auditory attentional deficits in patients with schizophrenia. A positron emission tomography study.

Source

Archives of General Psychiatry. 53(7):633-41, 1996 Jul.

Abstract

BACKGROUND: Patients with schizophrenia have frequently been found to perform poorly on tasks requiring selective attention, defined as the ability to focus attention on relevant information while simultaneously ignoring irrelevant stimuli. This study explores the brain mechanisms mediating attentional processing in patients with schizophrenia by measuring their regional cerebral blood flow (rCBF) with positron emission tomography using [15O] water as they performed tasks that differed systematically in attentional demand. METHODS: Ten schizophrenic patients (either neurolepticnaive or withdrawn from medication) (patient group) and 10 normal volunteers (control group) performed auditory target detection tasks. Different types of auditory stimuli (environmental sounds, meaningless speech sounds, and words) were presented either binaurally (ie, same sounds in both ears) or dichotically (simultaneous and different sounds in the 2 ears). In dichotic conditions, subjects were instructed to focus on either their left or right ear. RESULTS: Initial subtraction-based image analyses sought significant rCBF changes anywhere in the brain. Patients consistently had less significant activation than controls in right superotemporal gyrus (STG). Follow-up analyses used regions of interest traced on individual magnetic resonance images to precisely measure rCBF in STG. Unlike controls, patients had higher rCBF in the left STG during all activation conditions. CONCLUSIONS: The abnormal task-related rCBF asymmetry in STG of schizophrenic patients may indicate an isolated temporal lobe deficit, but it may also indicate abnormality in the thalamocortical circuitry mediating selective attention and/or in the brain systems that integrate auditory processing in the 2 hemispheres.

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Authors

Andreasen NC. O'Leary DS. Flaum M. Nopoulos P. Watkins

GL. Boles Ponto LL. Hichwa RD.

Institution

Mental Health Clinical Research Centre, University of Iowa College of Medicine, Iowa City, USA.

Title

Hypofrontality in schizophrenia: distributed dysfunctional circuits in neuroleptic-naive patients.

Source

Lancet. 349(9067):1730-4, 1997 Jun 14.

Abstract

BACKGROUND: There have been reports that patients with schizophrenia have decreased metabolic activity in prefrontal cortex. However, findings have been confounded by medication effects, chronic illness, and difficulties of measurement. We aimed to address these problems by examination of cerebral blood flow with positron emission tomography (PET). METHODS: We studied 17 neuroleptic-naive patients at the early stages of illness by means of image analysis and statistical methods that can detect abnormalities at the gyral level. FINDINGS: An initial omnibus test with a randomisation analysis indicated that patients differed from normal controls at the 0.06 level. In the follow-up analysis, three separate prefrontal regions had decreased perfusion (lateral, orbital, medial), as well as regions in inferior temporal and parietal cortex that are known to be anatomically connected. Regions with increased perfusion were also identified (eg, thalamus, cerebellum, retrosplenial cingulate), which suggests an imbalance in distributed cortical and subcortical circuits. INTERPRETATION: These distributed dysfunctional circuits may form the neural basis of schizophrenia through cognitive impairment of the brain, which prevents it from processing input efficiently and producing output effectively, thereby leading to symptoms such as hallucinations, delusions, and loss of volition.

Authors

Andreasen NC. Arndt S. Cizadlo T. O'Leary DS. Watkins

GL. Ponto LL. Hichwa RD.

Institution

Mental Health Clinical Research Center, University of Iowa College of Medicine, Iowa City 52242, USA.

Title

Sample size and statistical power in [15O]H2O studies of human cognition.

Source

Journal of Cerebral Blood Flow & Metabolism. 16(5):804-16, 1996 Sep.

Abstract

Determining the appropriate sample size is a crucial component of positron emission tomography (PET) studies. Power calculations, the traditional method for determining sample size, were developed for hypothesis-testing approaches to data analysis. This method for determining sample size is challenged by the complexities of PET data analysis: use of exploratory analysis strategies, search for multiple correlated nodes on interlinked networks, and analysis of large numbers of pixels that may have correlated values due to both anatomical and functional dependence. We examine the effects of variable sample size in a study of human memory, comparing large (n = 33), medium (n = 16,17), small (n = 11, 11, 11), and very small (n = 6,6,7,7,7) samples. Results from the large sample are assumed to be the "gold standard." The primary criterion for assessing sample size is replicability. This is evaluated using a hierarchically ordered group of parameters: pattern of peaks, location of peaks, number of peaks, size (volume) of peaks, and intensity of the associated t (or z) statistic. As sample size decreases, false negatives begin to appear, with some loss of pattern and peak detection; there is no corresponding increase in false positives. The results suggest that good replicability occurs with a sample size of 10-20 subjects in studies of human cognition that use paired subtraction comparisons of single experimental/baseline conditions with blood flow differences ranging from 4 to 13%.

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Authors

Andreasen NC. O'Leary DS. Cizadlo T. Arndt S. Rezai K.

Ponto LL. Watkins GL. Hichwa RD.

Institution

Mental Health Clinical Research Center, University of Iowa College of

Medicine and Hospitals and Clinics, Iowa City 52242, USA.

Title

Schizophrenia and cognitive dysmetria: a positron-emission tomography study of dysfunctional prefrontal-thalamic-cerebellar circuitry.

Source

Proceedings of the National Academy of Sciences of the United States of

America. 93(18):9985-90, 1996 Sep 3.

Abstract

Patients suffering from schizophrenia display subtle cognitive abnormalities that may reflect a difficulty in rapidly coordinating the steps that occur in a variety of mental activities. Working interactively with the prefrontal cortex, the cerebellum may play a role in coordinating both motor and cognitive performance. This positron-emission tomography study suggests the presence of a prefrontal-thalamic-cerebellar network that is activated when normal subjects recall complex narrative material, but is dysfunctional in schizophrenic patients when they perform the same task. These results support a role for the cerebellum in cognitive functions and suggest that patients with schizophrenia may suffer from a "cognitive dysmetria" due to dysfunctional prefrontal-thalamic-cerebellar circuitry.

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Authors

Andreasen NC. O'Leary DS. Arndt S. Cizadlo T. Hurtig R. Rezai K.

Watkins GL. Ponto LL. Hichwa RD.

Institution

Mental Health Clinical Research Center, University of Iowa Hospitals and Clinics, College of Medicine, Iowa City 52242, USA.

Title

Short-term and long-term verbal memory: a positron emission tomography study.

Source

Proceedings of the National Academy of Sciences of the United States of America. 92(11):5111-5, 1995 May 23.

Abstract

Short-term and long-term retention of experimentally presented words were compared in a sample of 33 healthy normal volunteers by the [15O]H2O method with positron emission tomography (PET). The design included three conditions. For the long-term condition, subjects thoroughly studied 18 words 1 week before the PET study. For the short-term condition, subjects were shown another set of 18 words 60 sec before imaging, with instructions to remember them. For the baseline condition, subtracted from the two memory conditions, subjects read a third set of words that they had not previously seen in the experiment. Similar regions were activated in both short-term and long-term conditions: large right frontal areas, biparietal areas, and the left cerebellum. In addition, the short-term condition also activated a relatively large region in the left prefrontal region. These complex distributed circuits appear to represent the neural substrates for aspects of memory such as encoding, retrieval, and storage. They indicate that circuitry involved in episodic memory has much larger cortical and cerebellar components than has been emphasized in earlier lesion studies.

Authors

Damasio H. Grabowski TJ. Tranel D. Hichwa RD. Damasio

AR.

Institution

Department of Neurology, Division of Behavioral Neurology and CognitiveNeuroscience, University of Iowa College of Medicine, Iowa City, 52242, USA.

Title

A neural basis for lexical retrieval [see comments] [published erratum appears in Nature 1996 Jun 27;381(6595):810].

Comments

Comment in: Nature 1996 Apr 11;380(6574):485-6

Source

Nature. 380(6574):499-505, 1996 Apr 11.

Abstract

Two parallel studies using positron emission tomography, one conducted in neurological patients with brain lesions, the other in normal individuals, indicate that the normal process of retrieving words that denote concrete entities depends in part on multiple regions of the left cerebral hemisphere, located outside the classic language areas. Moreover, anatomically separable regions tends to process words for distinct kinds of items.

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Authors

Paradiso S. Crespo Facorro B. Andreasen NC. O'Leary DS.

Watkins LG. Boles Ponto L. Hichwa RD.

Institution

Department of Psychiatry Administration, University of Iowa College of Medicine,

Iowa City 52242, USA.

Title

Brain activity assessed with PET during recall of word lists and narratives.

Source

Neuroreport. 8(14):3091-6, 1997 Sep 29.

Abstract

This study investigated the functional neuroanatomy involved in retrieval of structured versus unstructured verbal information. We compared cerebral blood flow using PET with the [15O]water method while subjects engaged in recall of novel and practised narratives and lists of unrelated words. Left orbital frontal cortex was activated during recall of both novel and practised unrelated words. Right parietal cortex was relatively more active during recall of the novel word list. Right orbital frontal cortex and anterior cingulate were relatively more active during recall of the practised but not the novel word list. These results are consistent with the role of left orbital frontal cortex in retrieval of unstructured verbal information. Right orbital frontal activity suggests that cognitive strategies may be involved in retrieval of well-practised words.

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Authors

Andreasen NC. O'Leary DS. Arndt S. Cizadlo T. Rezai K.

Watkins GL. Ponto LL. Hichwa RD.

Institution

Department of Psychiatry, University of Iowa Hospitals and Clinics, Iowa City

52242, USA.

Title

I. PET studies of memory: novel and practiced free recall of complex narratives.

Source

Neuroimage. 2(4):284-95, 1995 Dec.

Abstract

Positron Emission Tomography (PET) with the tracer H215O 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 60 s 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.

Authors

Hichwa RD.

Institution

Department of Psychiatry, University of Iowa Hospitals and Clinics, Iowa City 52242, USA.

Title

II. PET studies of memory: novel versus practiced free recall of word lists.

Source

Neuroimage. 2(4):296-305, 1995 Dec.

Abstract

Positron emission tomography (PET) with the tracer H215O 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 60 s 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 tasks-specific. In addition, these results support a significant role for the cerebellum in cognitive functions such as memory.

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Authors

O'Leary DS. Andreason NC. Hurtig RR. Hichwa RD.

Watkins GL. Ponto LL. Rogers M. Kirchner PT.

Institution

Department of Psychiatry, University of Iowa Hospitals and Clinics, Iowa City 52242-1057, USA.

Title

A positron emission tomography study of binaurally and dichotically presented stimuli: effects of level of language and directed attention.

Source

Brain & Language. 53(1):20-39, 1996 Apr.

Abstract

Regional cerebral blood flow (rCBF) was measured using positron emission tomography with oxygen- 15 labeled water as 10 normal subjects listened to three types of auditory stimuli (environmental sounds, meaningless speech, and words) presented binaurally or dichotically. Binaurally presented environmental sounds and words caused similar bilateral rCBF increases in left and right superior temporal gyri. Dichotically presented stimuli (subjects attended to left or right ears) caused asymmetric activation in the temporal lobes, resulting from increased rCBF in temporal lobe regions contralateral to the attended ear and decreased rCBF in the opposite hemisphere. The results indicate that auditorily presented language and non-language stimuli activate similar temporal regions, that dichotic stimulation dramatically changes rCBF in temporal lobes, and that the change is due both to attentional mechanisms and to hemispheric specialization.

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Authors

Andreasen NC. O'Leary DS. Cizadlo T. Arndt S. Rezai K.

Watkins GL. Ponto LL.

Hichwa RD.

Institution

Department of Psychiatry, University of Iowa Hospitals and Clinics, Iowa City 52242, USA.

Title

Remembering the past: two facets of episodic memory explored with positron emission tomography.

Source

American Journal of Psychiatry. 152(11):1576-85, 1995 Nov.

Abstract

OBJECTIVE: This study used positron emission tomography to examine two kinds of personal memory that are used in psychiatric evaluation: focused episodic memory (recall of past experience, employed in "taking a history") and random episodic memory (uncensored thinking about experience, examined during analytic therapy using free association). For comparison, a third memory task was used to tap impersonal memory that represents general information about the world ("semantic memory"). METHOD: Thirteen subjects were studied using the [15O]H2O method to obtain quantitative measurements of cerebral blood flow. The three conditions were subtracted and their relative relationships examined. RESULTS: The random episodic condition produced activations in widely distributed association cortex (right and left frontal, parietal, angular/supramarginal, and posterior inferior temporal regions). Focused episodic memory engaged a network that included the medial inferior frontal regions, precuneus/retrosplenial cingulate, anterior cingulate, thalamus, and cerebellum. The use of medial frontal regions and the precuneus/retrosplenial cingulate was common to both focused and random episodic memory. The major difference between semantic and episodic memory was activation of Broca's area and the left frontal operculum by semantic memory. CONCLUSIONS: These results indicate that free-ranging mental activity (random episodic memory) produces large activations in association cortex and may reflect both active retrieval of past experiences and planning of future experiences. Focused episodic memory shares some components of this circuit (inferior frontal and precuneus), which may reflect the time-linked components of both aspects of episodic memory, and which permit human beings to experience personal identity, consciousness, and self-awareness. 

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Authors

Argenyi EE. Dogan AS. Urdaneta LF. Ponto LL.

Hichwa RD. Watkins GL.

Institution

Department of Radiology, University of Iowa, Iowa City 52242, USA.

Title

Detection of unsuspected metastasis in a melanoma patient with positron emission tomography.

Source

Clinical Nuclear Medicine. 20(8):744-7, 1995 Aug.

Authors

Narayana S. Hichwa RD. Boles Ponto LL. Ponto JA.

Watkins GL.

Institution

Department of Radiology, University of Iowa, Iowa City 52242, USA.

Title

Dosimetry of [15O]water: a physiologic approach.

Source

Medical Physics. 23(1):159-68, 1996 Jan.

Abstract

Earlier dosimetry estimates for [15O]water assumed its instantaneous equilibrium with total body water. This assumption leads to an underestimation of the absorbed doses to organs with high blood flows, since the biodistribution of this short-lived radiopharmaceutical is dependent upon blood flow to organs. We have developed a physiologically based whole body blood flow model (WBBFM) using a commercially available icon-driven mathematical simulation software package and applied it to the reevaluation of [15O]water dosimetry in humans. The WBBFM uses multiple parallel compartments to represent organs, heart chambers, the injection site for [15O]water, and blood sampling sites (arterial and venous). Input values to the WBBFM include organ blood flows, organ masses, organ water volumes, organ:blood partition coefficients, injected activity and S-values of [15O]. The WBBFM is based on the same assumptions that are used in calculating regional blood flow using [15O]water and simulates the human body closely in its physiologic response. The activity in each organ is derived from the simulation and is used to calculate absorbed doses. The WBBFM calculated absorbed doses in microGy/MBq (mrad/mCi) to various organs are as follows: simulation and is used to calculate absorbed doses. The WBBFM calculated absorbed doses in microGy/MBq (mrad/mCi) to various organs are as follow: heart--2.66 (9.84), kidneys--2.20 (8.15), thyroid--1.83 (6.78), brain--1.66 (6.13), ovaries--1.25 (4.61), breast--1.24 (4.59), and small intestine--1.03 (3.83). These values are approximately two- to threefold higher than the earlier estimates of Kearfott [J. Nucl. Med. 23, 1031-1037 (1982)] and similar to the recent findings of Herscovitch et al. [J. Nucl. Med. 34, 155P (1983)]. We believe this approach yields more realistic dosimetry estimates for [15O]water. Accordingly, we have revised the amount of [15O]water administered during regional blood flow studies at our institution. The relative ease and accuracy of this approach suggests its usefulness in dosimetry estimation for other freely diffusible radiopharmaceuticals.

Authors

Argenyi EE. Ponto LL. Hichwa RD.

Watkins GL. Kirchner PT. Ryals TJ.

Institution

Department of Radiology 3JPP, University of Iowa Hospitals and Clinics, Iowa City 52242, USA.

Title

Follow-up of treatment of a cerebral arteriovenous malformation with acetazolamide and positron emission tomography.

Source

Clinical Nuclear Medicine. 20(7):639-41, 1995 Jul.

 Authors

Kahn D. Weiner GJ. Ben-Haim S. Ponto LL. Madsen MT.

Bushnell DL. Watkins GL. Argenyi EA.

Hichwa RD.

Institution

Department of Radiology, University of Iowa College of Medicine, Iowa City.

Title

Positron emission tomographic measurement of bone marrow blood flow to the pelvis and lumbar vertebrae in young normal adults [published erratum appears in Blood 1994 Nov 15;84(10):3602].

Source

Blood. 83(4):958-63, 1994 Feb 15.

Abstract

Ten young normal adults had pelvic and lumbar vertebral body bone marrow blood flow examined using [15O]water and positron emission tomography (PET) in a study designed to assess the feasibility and reproducibility of the PET technique for measuring marrow blood flow to various marrow regions. The procedure was well tolerated. Repeated blood flow measurements obtained from two consecutive [15O]water exams on each individual subject were highly reproducible. In addition, there was minimal variation in marrow blood flow from individual to individual and no gender differences were noted. In contrast, mean +/- SD bone marrow blood flows (expressed as milliliters per minute per 100 g) at selected anatomical sites were significantly different and were as follows: lower lumbar vertebral bodies, 17.6 +/- 3.1; most posterior and superior pelvis (conventional site of percutaneous bone marrow biopsy), 14.3 +/- 3.1; and total superior pelvis, 11.1 +/- 2.0. We conclude that PET is a relatively noninvasive, simple, and reproducible technique for measuring bone marrow blood flow. Marrow blood flow is consistent between normal young subjects, but varies significantly between different anatomic regions of the marrow.

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Authors

Ponto LL. Ponto JA.

Institution

Department of Radiology, University of Iowa, Iowa City.

Title

Uses and limitations of positron emission tomography in clinical pharmacokinetics/dynamics (Part I). [Review] [0 refs]

Source

Clinical Pharmacokinetics. 22(3):211-22, 1992 Mar.

Abstract

Positron emission tomography (PET) involves imaging the biodistribution and tissue localisation of small amounts of radiolabelled biomolecules or drugs. In Part I of this article, the applications of pharmacokinetics in PET are discussed in order to derive quantitative measures of physiological function. Part II will examine the use of PET imaging as a tool to study the pharmacokinetics and pharmacodynamics of specific drugs. [References: 0]

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Authors

Ponto LL. Ponto JA.

Institution

PET Imaging Center, Department of Radiology, University of Iowa, Iowa City.

Title

Uses and limitations of positron emission tomography in clinical pharmacokinetics/dynamics (Part II). [Review] [180 refs]

Source

Clinical Pharmacokinetics. 22(4):274-83, 1992 Apr.

Abstract

Positron emission tomography (PET) involves imaging the biodistribution and tissue localisation of small amounts of radiolabelled biomolecules or drugs. In Part I of this article, which appeared in the previous issue of the Journal, the applications of pharmacokinetics in PET were discussed in order to derive quantitative measures of physiological function. Part II examines the use of PET imaging as a tool to study the pharmacokinetics and pharmacodynamics of specific drugs. [References: 180]

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University of Michigan

Authors

Gilman S. Markel DS. Koeppe RA. Junck L. Kluin KJ. Gebarski SS.

Hichwa RD.

Institution

Department of Neurology, University of Michigan, Ann Arbor 48109-0316.

Title

Cerebellar and brainstem hypometabolism in olivopontocerebellar atrophy detected with positron emission tomography.

Source

Annals of Neurology. 23(3):223-30, 1988 Mar.

Abstract

We studied local cerebral metabolic rates for glucose (1CMRglc) with 18F-2-fluoro-2-deoxy-D-glucose and positron emission tomography (PET) in 30 patients with olivopontocerebellar atrophy (OPCA) and 30 age-matched control subjects without neurological disease. The diagnosis of OPCA was based on the history and physical findings and on the exclusion of other causes of cerebellar ataxia by means of laboratory investigations. Computed tomographic scans revealed some degree of atrophy of the cerebellum in most patients with OPCA, and many also had atrophy of the brainstem. PET studies in these patients revealed significant hypometabolism in the cerebellar hemispheres, cerebellar vermis, and brainstem in comparison with the normal control subjects. A significant relationship was found between the degree of atrophy and the level of 1CMRglc in the cerebellum and brainstem. Nevertheless, several patients had minimal atrophy and substantially reduced 1CMRglc, suggesting that atrophy does not fully account for the finding of hypometabolism. 1CMRglc was within normal limits for the thalamus and cerebral cortex. The data suggest that PET/1CMRglc may be useful as a diagnostic test in patients with the adult onset of cerebellar ataxia.

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Authors

Junck L. Gilman S. Rothley JR. Betley AT. Koeppe RA.

Hichwa RD.

Institution

Department of Neurology, University of Michigan Medical School, Ann Arbor.

Title

A relationship between metabolism in frontal lobes and cerebellum in normal subjects studied with PET.

Source

Journal of Cerebral Blood Flow & Metabolism. 8(6):774-82, 1988 Dec.

Abstract

Lesions of one cerebral hemisphere are associated with decreased glucose metabolism, oxygen metabolism, and blood flow in the contralateral cerebellar hemisphere. We used positron emission tomography to look for a functional relationship in cerebral metabolism between the cerebral cortex and the contralateral cerebellum in normal human subjects. Twenty-four normal subjects were scanned with [18F]fluoro-2-deoxy-D-glucose while in a resting state. Asymmetry in local CMRglu (LCMRglu) in the frontal cortex was strongly correlated with asymmetry in LCMRglu in the opposite direction in the cerebellar hemispheres (r = -0.60, p less than 0.001). Widespread subregions of the frontal cortex were found to contribute to this relationship. Considering these results together with previous studies demonstrating that frontal lesions are associated with decreased metabolism in the contralateral cerebellum, we conclude that the frontal cortex exerts a strong modulating influence on metabolism in the contralateral cerebellum in normal subjects, and that this influence may be asymmetrical.

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Authors

Cameron OG. Modell JG. Hichwa RD. Agranoff BW. Koeppe

RA.

Institution

Department of Psychiatry, University of Michigan Medical Center, Ann Arbor 48109-0722.

Title

Changes in sensory-cognitive input: effects on cerebral blood flow.

Source

Journal of Cerebral Blood Flow & Metabolism. 10(1):38-42, 1990 Jan.

Abstract

Eight healthy right-handed young men were subjected to local CBF measurement by [15O]water and positron emission tomography during partial sensory deprivation and during sensory-cognitive activation; physiological, hormonal, and subjective stress measurements were also performed. Results indicated that (a) "whole-brain" CBF increased during activation; (b) the greatest increase in CBF was in the primary visual cortex; (c) differences between hemispheres were not observed, but CBF was greater anteriorly than posteriorly in the deprivation condition only; (d) within-subject variability of CBF was not influenced by the sensory-cognitive condition; and (e) the procedure was not stressful.

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Authors

Giordani B. Berent S. Boivin MJ. Penney JB. Lehtinen S. Markel DS.

Hollingsworth Z. Butterbaugh G. Hichwa RD. Gusella JF.

et al.

Institution

Department of Psychiatry, University of Michigan, Ann Arbor.

Title

Longitudinal neuropsychological and genetic linkage analysis of persons at risk for Huntington's disease.

Source

Archives of Neurology. 52(1):59-64, 1995 Jan.

Abstract

OBJECTIVE: To determine (1) whether the neuropsychological profiles of healthy individuals at risk (AR) for Huntington's disease who were positive (AR/+) or negative (AR/-) for the Huntington's disease genetic marker differed from those of symptomatic patients with Huntington's disease and normal control individuals and (2) whether the neuropsychological performance of the two AR groups differed from each other on three assessments during a 4-year span. DESIGN: Case-control, double-blind study, with AR status determined by genetic linkage analysis (G8 probe), in addition to examination of trinucleotide repeats for most AR subjects. SETTING: The Neuropsychology Program in the Department of Psychiatry and the Department of Neurology at the University of Michigan Medical Center, Ann Arbor, a tertiary care center. PARTICIPANTS: Eight subjects matched as closely as possible for age, gender, and education in each of the following groups: AR/+, AR/-, normal control, and Huntington's disease. MEASURES: A battery of neuropsychological tasks, including measures of intelligence, memory, problem solving, and motor ability. RESULTS: Although both AR groups demonstrated variability on select intellectual subtests relative to normal subjects, they did not differ from each other on the three assessments during a 4-year span. Patients with Huntington's disease performed more poorly than the other groups across a range of neuropsychological measures. CONCLUSIONS: These results do not support previous evaluations concluding that AR/+ individuals demonstrate cognitive impairments as compared with AR/- individuals. Findings in earlier studies without genetic linkage analysis of lower performance of AR individuals, including children, as compared with normal controls may relate to extraneous environmental and familial issues that interfere with intellectual development.

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University of Pennsylvania

Authors

Karp JS. Daube-Witherspoon ME. Hoffman EJ. Lewellen TK. Links JM. Wong

WH. Hichwa RD. Casey ME. Colsher JG. Hitchens RE. et al.

Institution

Department of Radiology, University of Pennsylvania, Philadelphia.

Title

Performance standards in positron emission tomography [see comments].

Comments

Comment in: J Nucl Med 1992 Jul;33(7):1429-31

Source

Journal of Nuclear Medicine. 32(12):2342-50, 1991 Dec.

Abstract

A standard set of performance measurements is proposed for use with positron emission tomographs. This set of measurements has been developed jointly by the Computer and Instrumentation Council of the Society of Nuclear Medicine and the National Electrical Manufacturers Association. The measurements include tests of spatial resolution, scatter fraction, sensitivity, count rate losses and randoms, uniformity, scatter correction, attenuation correction, and count rate linearity correction.

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