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Coupling of cerebral blood flow and functional connectivity is decreased in healthy aging. Brain Imaging Behav 2021; 14:436-450. [PMID: 31250268 DOI: 10.1007/s11682-019-00157-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Aging leads to cerebral perfusion and functional connectivity changes that have been assessed using various neuroimaging techniques. In addition, a link between these two parameters has been demonstrated in healthy young adults. In this work, we employed arterial spin labeling (ASL) fMRI to measure global and voxel-wise differences in cerebral blood flow (CBF) and intrinsic connectivity contrast (ICC) in the resting state in a group of cognitively normal elderly subjects and a group of cognitively normal young subjects, in order to assess the effects of aging on CBF-ICC coupling, which had not been previously evaluated. Our results showed age-related global and regional CBF decreases in prefrontal mesial areas, lateral frontal regions, insular cortex, lateral parietal areas, precuneus and occipital regions. Subcortically, perfusion was reduced in the medial thalamus and caudate nucleus. ICC was also found reduced with age in prefrontal cortical areas and insular cortex, affecting key nodes of the default mode and salience networks. Areas of ICC and CBF decrease partially overlapped, however, the CBF reduction was more extensive and encompassed more areas. This dissociation was accompanied by a decrease in CBF-ICC coupling. These results suggest that aging leads to a disruption in the relationship between CBF and intrinsic functional connectivity that could be due to neurovascular dysregulation.
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Sander CY, Hansen HD, Wey HY. Advances in simultaneous PET/MR for imaging neuroreceptor function. J Cereb Blood Flow Metab 2020; 40:1148-1166. [PMID: 32169011 PMCID: PMC7238372 DOI: 10.1177/0271678x20910038] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hybrid imaging using PET/MRI has emerged as a platform for elucidating novel neurobiology, molecular and functional changes in disease, and responses to physiological or pharmacological interventions. For the central nervous system, PET/MRI has provided insights into biochemical processes, linking selective molecular targets and distributed brain function. This review highlights several examples that leverage the strengths of simultaneous PET/MRI, which includes measuring the perturbation of multi-modal imaging signals on dynamic timescales during pharmacological challenges, physiological interventions or behavioral tasks. We discuss important considerations for the experimental design of dynamic PET/MRI studies and data analysis approaches for comparing and quantifying simultaneous PET/MRI data. The primary focus of this review is on functional PET/MRI studies of neurotransmitter and receptor systems, with an emphasis on the dopamine, opioid, serotonin and glutamate systems as molecular neuromodulators. In this context, we provide an overview of studies that employ interventions to alter the activity of neuroreceptors or the release of neurotransmitters. Overall, we emphasize how the synergistic use of simultaneous PET/MRI with appropriate study design and interventions has the potential to expand our knowledge about the molecular and functional dynamics of the living human brain. Finally, we give an outlook on the future opportunities for simultaneous PET/MRI.
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Affiliation(s)
- Christin Y Sander
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, MA, USA
| | - Hanne D Hansen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, MA, USA.,Neurobiology Research Unit and NeuroPharm, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Hsiao-Ying Wey
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, MA, USA
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Hernandez-Garcia L, Nielsen JF, Noll DC. Improved sensitivity and temporal resolution in perfusion FMRI using velocity selective inversion ASL. Magn Reson Med 2018; 81:1004-1015. [PMID: 30187951 DOI: 10.1002/mrm.27461] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/29/2018] [Accepted: 06/30/2018] [Indexed: 12/19/2022]
Abstract
PURPOSE This work aims to investigate the utility of velocity selective inversion pulses for perfusion weighted functional MRI. METHODS Tracer kinetic properties of velocity selective inversion (VSI) pulses as an input function for an arterial spin labeling (ASL) experiment were characterized in a group of healthy participants. Numerical simulations were conducted to search for a robust set of timing parameters for FMRI time series acquisition with maximal signal to noise ratio efficiency. The performance of three VSI pulse sequences with different timing parameters was compared with a pseudocontinuous ASL sequence in a simple FMRI experiment conducted on healthy participants. RESULTS The fit to the tracer kinetic model yielded arterial CBV of 1.24% ± 0.52% and 0.45 ± 0.11% and perfusion rates of 60.8 ± 32.3 and 34.4 ± 5.4 mL/min/100 g for gray and white matter, respectively. Bolus arrival times were estimated as 75.7 ± 21 ms and 349 ± 78 ms for gray and white matter, respectively. The FMRI experiments showed that VSI pulses yield comparable sensitivity to PCASL with similar timing parameters (TR = 4 s). However, VSI pulses could be used at a faster acquisition speed (TR = 3 s) and were more sensitive to neuronal activity than PCASL pulses, as evidenced by the 31% higher Z scores obtained on average in the active regions. CONCLUSION VSI pulses can be very beneficial for perfusion weighted functional MRI because of their tracer kinetic characteristics, which allow a faster acquisition rate while maintaining an efficient labeling input function.
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Affiliation(s)
| | | | - Douglas C Noll
- University of Michigan FMRI Laboratory, Ann Arbor, Michigan
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Jennings JR, Heim AF, Sheu LK, Muldoon MF, Ryan C, Gach HM, Schirda C, Gianaros PJ. Brain Regional Blood Flow and Working Memory Performance Predict Change in Blood Pressure Over 2 Years. Hypertension 2017; 70:1132-1141. [PMID: 29038202 DOI: 10.1161/hypertensionaha.117.09978] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 07/27/2017] [Accepted: 09/14/2017] [Indexed: 12/27/2022]
Abstract
Hypertension is a presumptive risk factor for premature cognitive decline. However, lowering blood pressure (BP) does not uniformly reverse cognitive decline, suggesting that high BP per se may not cause cognitive decline. We hypothesized that essential hypertension has initial effects on the brain that, over time, manifest as cognitive dysfunction in conjunction with both brain vascular abnormalities and systemic BP elevation. Accordingly, we tested whether neuropsychological function and brain blood flow responses to cognitive challenges among prehypertensive individuals would predict subsequent progression of BP. Midlife adults (n=154; mean age, 49; 45% men) with prehypertensive BP underwent neuropsychological testing and assessment of regional cerebral blood flow (rCBF) response to cognitive challenges. Neuropsychological performance measures were derived for verbal and logical memory (memory), executive function, working memory, mental efficiency, and attention. A pseudo-continuous arterial spin labeling magnetic resonance imaging sequence compared rCBF responses with control and active phases of cognitive challenges. Brain areas previously associated with BP were grouped into composites for frontoparietal, frontostriatal, and insular-subcortical rCBF areas. Multiple regression models tested whether BP after 2 years was predicted by initial BP, initial neuropsychological scores, and initial rCBF responses to cognitive challenge. The neuropsychological composite of working memory (standardized beta, -0.276; se=0.116; P=0.02) and the frontostriatal rCBF response to cognitive challenge (standardized beta, 0.234; se=0.108; P=0.03) significantly predicted follow-up BP. Initial BP failed to significantly predict subsequent cognitive performance or rCBF. Changes in brain function may precede or co-occur with progression of BP toward hypertensive levels in midlife.
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Affiliation(s)
- J Richard Jennings
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.).
| | - Alicia F Heim
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
| | - Lei K Sheu
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
| | - Matthew F Muldoon
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
| | - Christopher Ryan
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
| | - H Michael Gach
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
| | - Claudiu Schirda
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
| | - Peter J Gianaros
- From the Departments of Psychiatry and Psychology, University of Pittsburgh, PA (J.R.J., A.F.H., L.K.S., M.F.M., C.R., C.S., P.J.G.); and Department of Radiation Oncology (H.M.G.), Department of Radiology (H.M.G.), and Department of Biomedical Engineering (H.M.G.),Washington University in St. Louis, MO (H.M.G.)
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Kundu P, Voon V, Balchandani P, Lombardo MV, Poser BA, Bandettini PA. Multi-echo fMRI: A review of applications in fMRI denoising and analysis of BOLD signals. Neuroimage 2017; 154:59-80. [PMID: 28363836 DOI: 10.1016/j.neuroimage.2017.03.033] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 03/15/2017] [Accepted: 03/16/2017] [Indexed: 01/16/2023] Open
Abstract
In recent years the field of fMRI research has enjoyed expanded technical abilities related to resolution, as well as use across many fields of brain research. At the same time, the field has also dealt with uncertainty related to many known and unknown effects of artifact in fMRI data. In this review we discuss an emerging fMRI technology, called multi-echo (ME)-fMRI, which focuses on improving the fidelity and interpretability of fMRI. Where the essential problem of standard single-echo fMRI is the indeterminacy of sources of signals, whether BOLD or artifact, this is not the case for ME-fMRI. By acquiring multiple echo images per slice, the ME approach allows T2* decay to be modeled at every voxel at every time point. Since BOLD signals arise by changes in T2* over time, an fMRI experiment sampling the T2* signal decay can be analyzed to distinguish BOLD from artifact signal constituents. While the ME approach has a long history of use in theoretical and validation studies, modern MRI systems enable whole-brain multi-echo fMRI at high resolution. This review covers recent multi-echo fMRI acquisition methods, and the analysis steps for this data to make fMRI at once more principled, straightforward, and powerful. After a brief overview of history and theory, T2* modeling and applications will be discussed. These applications include T2* mapping and combining echoes from ME data to increase BOLD contrast and mitigate dropout artifacts. Next, the modeling of fMRI signal changes to detect signal origins in BOLD-related T2* versus artifact-related S0 changes will be reviewed. A focus is on the use of ME-fMRI data to extract and classify components from spatial ICA, called multi-echo ICA (ME-ICA). After describing how ME-fMRI and ME-ICA lead to a general model for analysis of fMRI signals, applications in animal and human imaging will be discussed. Applications include removing motion artifacts in resting state data at subject and group level. New imaging methods such as multi-band multi-echo fMRI and imaging at 7T are demonstrated throughout the review, and a practical analysis pipeline is described. The review culminates with evidence from recent studies of major boosts in statistical power from using multi-echo fMRI for detecting activation and connectivity in healthy individuals and patients with neuropsychiatric disease. In conclusion, the review shows evidence that the multi-echo approach expands the range of experiments that is practicable using fMRI. These findings suggest a compelling future role of the multi-echo approach in subject-level and clinical fMRI.
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Affiliation(s)
- Prantik Kundu
- Departments of Radiology and Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Valerie Voon
- Behavioral and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Priti Balchandani
- Departments of Radiology and Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michael V Lombardo
- Department of Psychology and Center for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus
| | - Benedikt A Poser
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, NL, The Netherlands
| | - Peter A Bandettini
- Section on Functional Imaging Methods, National Institute of Mental Health, Bethesda, MD, USA
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6
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Gur RE, Gur RC. Sex differences in brain and behavior in adolescence: Findings from the Philadelphia Neurodevelopmental Cohort. Neurosci Biobehav Rev 2016; 70:159-170. [PMID: 27498084 PMCID: PMC5098398 DOI: 10.1016/j.neubiorev.2016.07.035] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 01/17/2023]
Abstract
Sex differences in brain and behavior were investigated across the lifespan. Parameters include neurobehavioral measures linkable to neuroanatomic and neurophysiologic indicators of brain structure and function. Sexual differentiation of behavior has been related to organizational factors during sensitive periods of development, with adolescence and puberty gaining increased attention. Adolescence is a critical developmental period where transition to adulthood is impacted by multiple factors that can enhance vulnerability to brain dysfunction. Here we highlight sex differences in neurobehavioral measures in adolescence that are linked to brain function. We summarize neuroimaging studies examining brain structure, connectivity and perfusion, underscoring the relationship to sex differences in behavioral measures and commenting on hormonal findings. We focus on relevant data from the Philadelphia Neurodevelopmental Cohort (PNC), a community-based sample of nearly 10,000 clinically and neurocognitively phenotyped youths age 8-21 of whom 1600 have received multimodal neuroimaging. These data indicate early and pervasive sexual differentiation in neurocognitive measures that is linkable to brain parameters. We conclude by describing possible clinical implications.
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Affiliation(s)
- Raquel E Gur
- Brain Behavior Laboratory, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, USA.
| | - Ruben C Gur
- Brain Behavior Laboratory, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, USA
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7
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Harris AD, Puts NAJ, Anderson BA, Yantis S, Pekar JJ, Barker PB, Edden RAE. Multi-regional investigation of the relationship between functional MRI blood oxygenation level dependent (BOLD) activation and GABA concentration. PLoS One 2015; 10:e0117531. [PMID: 25699994 PMCID: PMC4336183 DOI: 10.1371/journal.pone.0117531] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 12/06/2014] [Indexed: 11/19/2022] Open
Abstract
Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD) response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.
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Affiliation(s)
- Ashley D. Harris
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, United States of America
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States of America
- * E-mail:
| | - Nicolaas A. J. Puts
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, United States of America
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States of America
| | - Brian A. Anderson
- Department of Psychological and Brain Sciences, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Steven Yantis
- Department of Psychological and Brain Sciences, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - James J. Pekar
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, United States of America
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States of America
| | - Peter B. Barker
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, United States of America
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States of America
| | - Richard A. E. Edden
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, United States of America
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, United States of America
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Avants BB, Duda JT, Kilroy E, Krasileva K, Jann K, Kandel BT, Tustison NJ, Yan L, Jog M, Smith R, Wang Y, Dapretto M, Wang DJJ. The pediatric template of brain perfusion. Sci Data 2015; 2:150003. [PMID: 25977810 PMCID: PMC4413243 DOI: 10.1038/sdata.2015.3] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 12/11/2014] [Indexed: 12/14/2022] Open
Abstract
Magnetic resonance imaging (MRI) captures the dynamics of brain development with multiple modalities that quantify both structure and function. These measurements may yield valuable insights into the neural patterns that mark healthy maturation or that identify early risk for psychiatric disorder. The Pediatric Template of Brain Perfusion (PTBP) is a free and public neuroimaging resource that will help accelerate the understanding of childhood brain development as seen through the lens of multiple modality neuroimaging and in relation to cognitive and environmental factors. The PTBP uses cross-sectional and longitudinal MRI to quantify cortex, white matter, resting state functional connectivity and brain perfusion, as measured by Arterial Spin Labeling (ASL), in 120 children 7-18 years of age. We describe the PTBP and show, as a demonstration of validity, that global summary measurements capture the trajectories that demarcate critical turning points in brain maturation. This novel resource will allow a more detailed understanding of the network-level, structural and functional landmarks that are obtained during normal adolescent brain development.
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Affiliation(s)
- Brian B Avants
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jeffrey T Duda
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Emily Kilroy
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Kate Krasileva
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Kay Jann
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Benjamin T Kandel
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Nicholas J Tustison
- Department of Radiology, University of Virginia, Charlottesville, Virginia 22904, USA
| | - Lirong Yan
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Mayank Jog
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Robert Smith
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Yi Wang
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Mirella Dapretto
- Department of Neurology, University of California, Los Angeles, California 90095, USA
| | - Danny J J Wang
- Department of Neurology, University of California, Los Angeles, California 90095, USA
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Frayne E, Coulson S, Adams R, Croxson GR. Self-regulatory fatigue after neurological and musculoskeletal injury: implications for physiotherapy management. PHYSICAL THERAPY REVIEWS 2015. [DOI: 10.1179/1743288x14y.0000000160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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10
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Evans JW, Kundu P, Horovitz SG, Bandettini PA. Separating slow BOLD from non-BOLD baseline drifts using multi-echo fMRI. Neuroimage 2014; 105:189-97. [PMID: 25449746 DOI: 10.1016/j.neuroimage.2014.10.051] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/17/2014] [Accepted: 10/21/2014] [Indexed: 11/26/2022] Open
Abstract
The functional magnetic resonance (fMRI) baseline is known to drift over the course of an experiment and is often attributed to hardware instability. These ultraslow fMRI fluctuations are inseparable from blood oxygenation level dependent (BOLD) changes in standard single echo fMRI and they are therefore typically removed before further analysis in both resting-state and task paradigms. However, some part of these fluctuations may be of neuronal origin, as neural activity can indeed fluctuate at the scale of several minutes or even longer, such as after the administration of drugs or during the ultradian rhythms. Here, we show that it is possible to separate the slow BOLD and non-BOLD drifts automatically using multi-echo fMRI and multi-echo independent components analysis (ME-ICA) denoising by demonstrating the detection of a visual signal evoked from a flickering checkerboard with slowly changing contrast.
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Affiliation(s)
- Jennifer W Evans
- Section on Functional Imaging Methods, LBC, NIMH, NIH, Bethesda, MD, USA.
| | - Prantik Kundu
- Section on Functional Imaging Methods, LBC, NIMH, NIH, Bethesda, MD, USA
| | | | - Peter A Bandettini
- Section on Functional Imaging Methods, LBC, NIMH, NIH, Bethesda, MD, USA
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Mandeville JB, Liu CH, Vanduffel W, Marota JJA, Jenkins BG. Data collection and analysis strategies for phMRI. Neuropharmacology 2014; 84:65-78. [PMID: 24613447 PMCID: PMC4058391 DOI: 10.1016/j.neuropharm.2014.02.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 02/07/2014] [Accepted: 02/25/2014] [Indexed: 12/24/2022]
Abstract
Although functional MRI traditionally has been applied mainly to study changes in task-induced brain function, evolving acquisition methodologies and improved knowledge of signal mechanisms have increased the utility of this method for studying responses to pharmacological stimuli, a technique often dubbed "phMRI". The proliferation of higher magnetic field strengths and the use of exogenous contrast agent have boosted detection power, a critical factor for successful phMRI due to the restricted ability to average multiple stimuli within subjects. Receptor-based models of neurovascular coupling, including explicit pharmacological models incorporating receptor densities and affinities and data-driven models that incorporate weak biophysical constraints, have demonstrated compelling descriptions of phMRI signal induced by dopaminergic stimuli. This report describes phMRI acquisition and analysis methodologies, with an emphasis on data-driven analyses. As an example application, statistically efficient data-driven regressors were used to describe the biphasic response to the mu-opioid agonist remifentanil, and antagonism using dopaminergic and GABAergic ligands revealed modulation of the mesolimbic pathway. Results illustrate the power of phMRI as well as our incomplete understanding of mechanisms underlying the signal. Future directions are discussed for phMRI acquisitions in human studies, for evolving analysis methodologies, and for interpretative studies using the new generation of simultaneous PET/MRI scanners. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.
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Affiliation(s)
- Joseph B Mandeville
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA.
| | - Christina H Liu
- National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD 20817, USA
| | - Wim Vanduffel
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - John J A Marota
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Bruce G Jenkins
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA
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12
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Impact of puberty on the evolution of cerebral perfusion during adolescence. Proc Natl Acad Sci U S A 2014; 111:8643-8. [PMID: 24912164 DOI: 10.1073/pnas.1400178111] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Puberty is the defining biological process of adolescent development, yet its effects on fundamental properties of brain physiology such as cerebral blood flow (CBF) have never been investigated. Capitalizing on a sample of 922 youths ages 8-22 y imaged using arterial spin labeled MRI as part of the Philadelphia Neurodevelopmental Cohort, we studied normative developmental differences in cerebral perfusion in males and females, as well as specific associations between puberty and CBF. Males and females had conspicuously divergent nonlinear trajectories in CBF evolution with development as modeled by penalized splines. Seventeen brain regions, including hubs of the executive and default mode networks, showed a robust nonlinear age-by-sex interaction that surpassed Bonferroni correction. Notably, within these regions the decline in CBF was similar between males and females in early puberty and only diverged in midpuberty, with CBF actually increasing in females. Taken together, these results delineate sex-specific growth curves for CBF during youth and for the first time to our knowledge link such differential patterns of development to the effects of puberty.
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Villien M, Bouzat P, Rupp T, Robach P, Lamalle L, Troprès I, Estève F, Krainik A, Lévy P, Warnking JM, Verges S. Changes in cerebral blood flow and vasoreactivity to CO2 measured by arterial spin labeling after 6days at 4350m. Neuroimage 2013; 72:272-9. [DOI: 10.1016/j.neuroimage.2013.01.066] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/26/2012] [Accepted: 01/23/2013] [Indexed: 12/22/2022] Open
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Parameterisation of multi-scale continuum perfusion models from discrete vascular networks. Med Biol Eng Comput 2013; 51:557-70. [PMID: 23345008 PMCID: PMC3627025 DOI: 10.1007/s11517-012-1025-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 12/21/2012] [Indexed: 10/28/2022]
Abstract
Experimental data and advanced imaging techniques are increasingly enabling the extraction of detailed vascular anatomy from biological tissues. Incorporation of anatomical data within perfusion models is non-trivial, due to heterogeneous vessel density and disparate radii scales. Furthermore, previous idealised networks have assumed a spatially repeating motif or periodic canonical cell, thereby allowing for a flow solution via homogenisation. However, such periodicity is not observed throughout anatomical networks. In this study, we apply various spatial averaging methods to discrete vascular geometries in order to parameterise a continuum model of perfusion. Specifically, a multi-compartment Darcy model was used to provide vascular scale separation for the fluid flow. Permeability tensor fields were derived from both synthetic and anatomically realistic networks using (1) porosity-scaled isotropic, (2) Huyghe and Van Campen, and (3) projected-PCA methods. The Darcy pressure fields were compared via a root-mean-square error metric to an averaged Poiseuille pressure solution over the same domain. The method of Huyghe and Van Campen performed better than the other two methods in all simulations, even for relatively coarse networks. Furthermore, inter-compartment volumetric flux fields, determined using the spatially averaged discrete flux per unit pressure difference, were shown to be accurate across a range of pressure boundary conditions. This work justifies the application of continuum flow models to characterise perfusion resulting from flow in an underlying vascular network.
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Nieto-Castañón A, Fedorenko E. Subject-specific functional localizers increase sensitivity and functional resolution of multi-subject analyses. Neuroimage 2012; 63:1646-69. [PMID: 22784644 PMCID: PMC3477490 DOI: 10.1016/j.neuroimage.2012.06.065] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/25/2012] [Accepted: 06/28/2012] [Indexed: 10/28/2022] Open
Abstract
One important goal of cognitive neuroscience is to discover and explain properties common to all human brains. The traditional solution for comparing functional activations across brains in fMRI is to align each individual brain to a template brain in a Cartesian coordinate system (e.g., the Montreal Neurological Institute template). However, inter-individual anatomical variability leads to decreases in sensitivity (ability to detect a significant activation when it is present) and functional resolution (ability to discriminate spatially adjacent but functionally different neural responses) in group analyses. Subject-specific functional localizers have been previously argued to increase the sensitivity and functional resolution of fMRI analyses in the presence of inter-subject variability in the locations of functional activations (e.g., Brett et al., 2002; Fedorenko and Kanwisher, 2009, 2011; Fedorenko et al., 2010; Kanwisher et al., 1997; Saxe et al., 2006). In the current paper we quantify this dependence of sensitivity and functional resolution on functional variability across subjects in order to illustrate the highly detrimental effects of this variability on traditional group analyses. We show that analyses that use subject-specific functional localizers usually outperform traditional group-based methods in both sensitivity and functional resolution, even when the same total amount of data is used for each analysis. We further discuss how the subject-specific functional localization approach, which has traditionally only been considered in the context of ROI-based analyses, can be extended to whole-brain voxel-based analyses. We conclude that subject-specific functional localizers are particularly well suited for investigating questions of functional specialization in the brain. An SPM toolbox that can perform all of the analyses described in this paper is publicly available, and the analyses can be applied retroactively to any dataset, provided that multiple runs were acquired per subject, even if no explicit "localizer" task was included.
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Affiliation(s)
- Alfonso Nieto-Castañón
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 43 Vassar Street, Building 46, Room 3037G, Cambridge, MA 02139, U.S.A, Phone: (617) 253–5774; fax: (617) 258–8654
| | - Evelina Fedorenko
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 43 Vassar Street, Building 46, Room 3037G, Cambridge, MA 02139, U.S.A, Phone: (617) 253–5774; fax: (617) 258–8654
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