Functional Magnetic Resonance Imaging Measures of Blood Flow Patterns in the Human Auditory Cortex in Response to Sound

1998 ◽  
Vol 41 (3) ◽  
pp. 538-548 ◽  
Author(s):  
Sean C. Huckins ◽  
Christopher W. Turner ◽  
Karen A. Doherty ◽  
Michael M. Fonte ◽  
Nikolaus M. Szeverenyi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Speech Stimuli ◽  
Complex Stimuli ◽  
Scanning Session ◽  
Auditory Research

Functional Magnetic Resonance Imaging (fMRI) holds exciting potential as a research and clinical tool for exploring the human auditory system. This noninvasive technique allows the measurement of discrete changes in cerebral cortical blood flow in response to sensory stimuli, allowing determination of precise neuroanatomical locations of the underlying brain parenchymal activity. Application of fMRI in auditory research, however, has been limited. One problem is that fMRI utilizing echo-planar imaging technology (EPI) generates intense noise that could potentially affect the results of auditory experiments. Also, issues relating to the reliability of fMRI for listeners with normal hearing need to be resolved before this technique can be used to study listeners with hearing loss. This preliminary study examines the feasibility of using fMRI in auditory research by performing a simple set of experiments to test the reliability of scanning parameters that use a high resolution and high signal-to-noise ratio unlike that presently reported in the literature. We used consonant-vowel (CV) speech stimuli to investigate whether or not we could observe reproducible and consistent changes in cortical blood flow in listeners during a single scanning session, across more than one scanning session, and in more than one listener. In addition, we wanted to determine if there were differences between CV speech and nonspeech complex stimuli across listeners. Our study shows reproducibility within and across listeners for CV speech stimuli. Results were reproducible for CV speech stimuli within fMRI scanning sessions for 5 out of 9 listeners and were reproducible for 6 out of 8 listeners across fMRI scanning sessions. Results of nonspeech complex stimuli across listeners showed activity in 4 out of 9 individuals tested.

scholarly journals Task Repetition Can Affect Functional Magnetic Resonance Imaging-Based Measures of Language Lateralization and Lead to Pseudoincreases in Bilaterality

2004 ◽  
Vol 24 (2) ◽  
pp. 179-187 ◽  
Author(s):  
Hubertus Lohmann ◽  
Michael Deppe ◽  
Andreas Jansen ◽  
Wolfram Schwindt ◽  
Stefan Knech
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Transcranial Doppler Sonography ◽  
Task Repetition ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Language Lateralization ◽  
Word Generation

Repeated functional magnetic resonance imaging (fMRI) during learning and recovery can inform us about functional reorganization in the brain. We examined how, in the absence of reorganization, simple task repetition affects measures of fMRI activation. We studied fMRI activation over 10 consecutive sessions of silent word generation in a healthy subject. Additionally, we performed functional transcranial Doppler sonography (fTCD) to learn about the temporal pattern of corresponding changes in cerebral blood flow velocity (CBFV) and pulsatility. With repetition, word generation-associated increases in heart rate diminished steadily. Task repetition also led to a net increase in CBFV bilaterally and to a bilateral increase in the number of activated voxels on fMRI. As a result, whereas the absolute interhemispheric difference of activated voxels remained constant, there was a decrease in the standard fMRI index for language lateralization [LIfMRI = 100 (activated voxels in left hemisphere - voxels in right)/(voxels in left + voxels in right)]. Thus task repetition can lead to changes in task-related autonomic drive and an augmentation of bihemispheric blood flow. This can mimic increasing bilaterality of brain activation.

scholarly journals Simulating Local Deformations in the Human Cortex Due to Blood Flow-Induced Changes in Mechanical Tissue Properties: Impact on Functional Magnetic Resonance Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Mahsa Zoraghi ◽  
Nico Scherf ◽  
Carsten Jaeger ◽  
Ingolf Sack ◽  
Sebastian Hirsch ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Brain Tissue ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Tissue Properties ◽  
The Relationship ◽  
The Brain

Investigating human brain tissue is challenging due to the complexity and the manifold interactions between structures across different scales. Increasing evidence suggests that brain function and microstructural features including biomechanical features are related. More importantly, the relationship between tissue mechanics and its influence on brain imaging results remains poorly understood. As an important example, the study of the brain tissue response to blood flow could have important theoretical and experimental consequences for functional magnetic resonance imaging (fMRI) at high spatial resolutions. Computational simulations, using realistic mechanical models can predict and characterize the brain tissue behavior and give us insights into the consequent potential biases or limitations of in vivo, high-resolution fMRI. In this manuscript, we used a two dimensional biomechanical simulation of an exemplary human gyrus to investigate the relationship between mechanical tissue properties and the respective changes induced by focal blood flow changes. The model is based on the changes in the brain’s stiffness and volume due to the vasodilation evoked by neural activity. Modeling an exemplary gyrus from a brain atlas we assessed the influence of different potential mechanisms: (i) a local increase in tissue stiffness (at the level of a single anatomical layer), (ii) an increase in local volume, and (iii) a combination of both effects. Our simulation results showed considerable tissue displacement because of these temporary changes in mechanical properties. We found that the local volume increase causes more deformation and consequently higher displacement of the gyrus. These displacements introduced considerable artifacts in our simulated fMRI measurements. Our results underline the necessity to consider and characterize the tissue displacement which could be responsible for fMRI artifacts.

Functional magnetic resonance imaging

2012 ◽  
pp. 196-201 ◽  
Author(s):  
E. T. Bullmore ◽  
J. Suckling
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Visual Stimulation ◽  
Single Photon ◽  
Photon Emission ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging

Functional magnetic resonance imaging (fMRI) is a relatively new technique for measuring changes in cerebral blood flow. The first fMRI studies, showing functional activation of the occipital cortex by visual stimulation and activation of the motor cortex by finger movement, were published in the early 1990s. In the years since then, fMRI has been used to investigate the physiological response to a wide variety of experimental procedures in both normal human subjects and diverse patient groups. In the next 10 years, fMRI will probably establish a role for itself in radiological and psychiatric practice; currently the clinical role of fMRI is limited to specialized applications such as assessment of hemispheric dominance prior to neurosurgery. The outstanding advantage of fMRI over alternative methods of imaging cerebral blood flow, such as positron emission tomo-graphy (PET) and single-photon emission computed tomography (SPECT), is that it does not involve exposure to radioactivity. This means that a single subject can safely be examined by fMRI on many occasions, and that the ethical problems of examining patients are minimized. Functional MRI also has superior spatial resolution (in the order of millimetres) and temporal resolution (in the order of seconds) compared with PET and SPECT. In this chapter, we provide an introduction to technical issues relevant to fMRI data acquisition, study design, and analysis. An introduction to the basic physical principles of magnetization and nuclear magnetic resonance, and the technology, is given in Chapter 2.3.7. Many excellent specialist texts covering all aspects of functional magnetic resonance imaging are available for the reader seeking more detailed treatment of the issues.

Functional magnetic resonance imaging for the determination of blood flow in symmetric uterine anomalies

2016 ◽  
Vol 10_2016 ◽  
pp. 73-79
Author(s):  
Makiyan Z.N. Makiyan ◽  
Adamyan L.V. Adamyan ◽  
Bychenko V.G. Bychenko ◽  
Miroshnikova N.A. Miroshnikova ◽  
Kozlova A.V. Kozlova ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Uterine Anomalies
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