scholarly journals BOLD Responses in Human Auditory Cortex Are More Closely Related to Transient MEG Responses Than to Sustained Ones

2010 ◽  
Vol 103 (4) ◽  
pp. 2015-2026 ◽  
Author(s):  
Alexander Gutschalk ◽  
Matti S. Hämäläinen ◽  
Jennifer R. Melcher
Keyword(s):  
Auditory Cortex ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Bold Fmri ◽  
Duty Cycles ◽  
Wide Range ◽  
Bold Responses ◽  
Tightly Coupled ◽  
Click Train

Blood oxygen level dependent–functional magnetic resonance imaging (BOLD–fMRI) and magnetoencephalographic (MEG) signals are both coupled to postsynaptic potentials, although their relationship is incompletely understood. Here, the wide range of BOLD–fMRI and MEG responses produced by auditory cortex was exploited to better understand the BOLD–fMRI/MEG relationship. Measurements of BOLD and MEG responses were made in the same subjects using the same stimuli for both modalities. The stimuli, 24-s sequences of click trains, had duty cycles of 2.5, 25, 72, and 100%. For the 2.5% sequence, the BOLD response was elevated throughout the sequence, whereas for 100%, it peaked after sequence onset and offset and showed a diminished elevation in between. On the finer timescale of MEG, responses at 2.5% consisted of a complex of transients, including N1m, to each click train of the sequence, whereas for 100% the only transients occurred at sequence onset and offset between which there was a sustained elevation in the MEG signal (a sustained field). A model that separately estimated the contributions of transient and sustained MEG signals to the BOLD response best fit BOLD measurements when the transient contribution was weighted 8- to 10-fold more than the sustained one. The findings suggest that BOLD responses in the auditory cortex are tightly coupled to the neural activity underlying transient, not sustained, MEG signals.

scholarly journals Low Frequency Stimulation of the Perforant Pathway Generates Anesthesia-Specific Variations in Neural Activity and BOLD Responses in the Rat Dentate Gyrus

2011 ◽  
Vol 32 (2) ◽  
pp. 291-305 ◽  
Author(s):  
Karla Krautwald ◽  
Frank Angenstein
Keyword(s):  
Dentate Gyrus ◽  
Stimulus Frequency ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Perforant Pathway ◽  
Bold Responses ◽  
Dependent Signal ◽  
Frequency Stimulation

To study how various anesthetics affect the relationship between stimulus frequency and generated functional magnetic resonance imaging (fMRI) signals in the rat dentate gyrus, the perforant pathway was electrically stimulated with repetitive low frequency (i.e., 0.625, 1.25, 2.5, 5, and 10 Hz) stimulation trains under isoflurane/N2O, isoflurane, medetomidine, and α-chloralose. During stimulation, the blood oxygen level-dependent signal intensity (BOLD response) and local field potentials in the dentate gyrus were simultaneously recorded to prove whether the present anesthetic controls the generation of a BOLD response via targeting general hemodynamic parameters, by affecting mechanisms of neurovascular coupling, or by disrupting local signal processing. Using this combined electrophysiological/fMRI approach, we found that the threshold frequency (i.e., the minimal frequency required to trigger significant BOLD responses), the optimal frequency (i.e., the frequency that elicit the strongest BOLD response), and the spatial distribution of generated BOLD responses are specific for each anesthetic used. Concurrent with anesthetic-dependent characteristics of the BOLD response, we found the pattern of stimulus-induced neuronal activity in the dentate gyrus is also specific for each anesthetic. Consequently, the anesthetic-specific influence on local signaling processes is the underlying cause for the observation that an identical stimulus elicits different BOLD responses under various anesthetics.

Identification of Cerebral Networks by Classification of the Shape of BOLD Responses

2003 ◽  
Vol 90 (1) ◽  
pp. 360-371 ◽  
Author(s):  
Giovanni d'Avossa ◽  
Gordon L. Shulman ◽  
Maurizio Corbetta
Keyword(s):  
Formal Analysis ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Match To Sample ◽  
Sustained Activity ◽  
Bold Responses ◽  
Transient Activity ◽  
Posterior Parietal ◽  
Time Courses

Changes in regional blood oxygen level dependent (BOLD) signals in response to brief visual stimuli can exhibit a variety of time-courses. To demonstrate the anatomical distribution of BOLD response shapes during a match to sample task, a formal analysis of their time-courses is presented. An event-related design was used to estimate regional BOLD responses evoked by a cue word, which instructed the subject to attend to the motion or color of an upcoming target, and those evoked by a briefly presented moving target consisting of colored dots. Regional BOLD time-courses were adequately represented by the linear combination of three orthogonal waveforms. BOLD response shapes were then classified using a fuzzy clustering scheme. Three classes (sustained, phasic, and negative) best characterized cue responses. Four classes (sustained, sustained-phasic, phasic, and bi-phasic) best characterized target responses. In certain regions, the shape of the BOLD responses was modulated by the instruction to attend to the target's motion or color. A left frontal and a posterior parietal region showed sustained activity when motion was cued and transient activity when color was cued. A right thalamic and a left lateral occipital region showed sustained activity when color was cued and transient activity when motion was cued. Following the target several regions showed more sustained activity during motion than color trials. In summary, the effect of the task variable was focal following the cue and widespread following the target. We conclude that the temporal patterns of neural activity affected the shape of the BOLD signal.

Characterization of the blood-oxygen level-dependent (BOLD) response in cat auditory cortex using high-field fMRI

NeuroImage ◽  
2013 ◽  
Vol 64 ◽  
pp. 458-465 ◽  
Author(s):  
Trecia A. Brown ◽  
Marc F. Joanisse ◽  
Joseph S. Gati ◽  
Sarah M. Hughes ◽  
Pam L. Nixon ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
High Field ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Bold Response ◽  
Oxygen Level ◽  
Blood Oxygen Level

scholarly journals Neural representations of own-voice in the human auditory cortex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Taishi Hosaka ◽  
Marino Kimura ◽  
Yuko Yotsumoto
Keyword(s):  
Auditory Cortex ◽  
Superior Temporal Gyrus ◽  
Neural Correlates ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Neural Representations ◽  
Human Auditory Cortex ◽  
The Voice

AbstractWe have a keen sensitivity when it comes to the perception of our own voices. We can detect not only the differences between ourselves and others, but also slight modifications of our own voices. Here, we examined the neural correlates underlying such sensitive perception of one’s own voice. In the experiments, we modified the subjects’ own voices by using five types of filters. The subjects rated the similarity of the presented voices to their own. We compared BOLD (Blood Oxygen Level Dependent) signals between the voices that subjects rated as least similar to their own voice and those they rated as most similar. The contrast revealed that the bilateral superior temporal gyrus exhibited greater activities while listening to the voice least similar to their own voice and lesser activation while listening to the voice most similar to their own. Our results suggest that the superior temporal gyrus is involved in neural sharpening for the own-voice. The lesser degree of activations observed by the voices that were similar to the own-voice indicates that these areas not only respond to the differences between self and others, but also respond to the finer details of own-voices.

Equal Degrees of Object Selectivity for Upper and Lower Visual Field Stimuli

2010 ◽  
Vol 104 (4) ◽  
pp. 2075-2081 ◽  
Author(s):  
Lars Strother ◽  
Adrian Aldcroft ◽  
Cheryl Lavell ◽  
Tutis Vilis
Keyword(s):  
Visual Field ◽  
Occipital Cortex ◽  
Recognition System ◽  
Blood Oxygen Level Dependent ◽  
Lower Visual Field ◽  
Blood Oxygen Level ◽  
Visual Areas ◽  
Bold Responses ◽  
Cortical Regions ◽  
Lateral Occipital Cortex

Functional MRI (fMRI) studies of the human object recognition system commonly identify object-selective cortical regions by comparing blood oxygen level–dependent (BOLD) responses to objects versus those to scrambled objects. Object selectivity distinguishes human lateral occipital cortex (LO) from earlier visual areas. Recent studies suggest that, in addition to being object selective, LO is retinotopically organized; LO represents both object and location information. Although LO responses to objects have been shown to depend on location, it is not known whether responses to scrambled objects vary similarly. This is important because it would suggest that the degree of object selectivity in LO does not vary with retinal stimulus position. We used a conventional functional localizer to identify human visual area LO by comparing BOLD responses to objects versus scrambled objects presented to either the upper (UVF) or lower (LVF) visual field. In agreement with recent findings, we found evidence of position-dependent responses to objects. However, we observed the same degree of position dependence for scrambled objects and thus object selectivity did not differ for UVF and LVF stimuli. We conclude that, in terms of BOLD response, LO discriminates objects from non-objects equally well in either visual field location, despite stronger responses to objects in the LVF.

scholarly journals BOLD and Perfusion Response to Finger-Thumb Apposition after Acetazolamide Administration: Differential Relationship to Global Perfusion

2003 ◽  
Vol 23 (7) ◽  
pp. 829-837 ◽  
Author(s):  
Gregory G. Brown ◽  
Lisa T. Eyler Zorrilla ◽  
Bassem Georgy ◽  
Sandra S. Kindermann ◽  
Eric C. Wong ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Individual Subject ◽  
Cerebrovascular Reserve ◽  
Global Cerebral Blood Flow ◽  
Hand Area ◽  
Cortical Perfusion

The authors studied the effects of altering global cerebral blood flow on both blood oxygen level–dependent (BOLD) response and perfusion response to finger-thumb apposition. A PICORE/QUIPSS II protocol was used to collect interleaved BOLD-weighted and perfusion-weighted images on eight finger-thumb apposition trials. Subjects were studied on a drug-free day and on a day when acetazolamide was administered between the second and third trials. After acetazolamide administration, resting cortical perfusion increased an average of 20% from preadministration levels, whereas the BOLD response to finger-thumb apposition decreased by an average of 35% in the S1M1 hand area. Contrary to predictions from the exhausted cerebrovascular reserve hypothesis and the oxygen limitation model, an effect of acetazolamide on cerebral blood flow response in the S1M1 hand area was not observed. Across the acetazolamide trials, BOLD response was inversely correlated with resting cortical perfusion for individual subject data. These results suggest that resting perfusion affects the magnitude of the BOLD response and is thus an important confounding factor in fMRI studies, and that the physiologic systems that increase cerebral blood flow in response to acetazolamide administration and systems that increase cerebral blood flow in response to altered neural activity appear to have additive effects.

scholarly journals Recent advances in renal imaging

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1867 ◽  
Author(s):  
Joshua M. Thurman ◽  
Faikah Gueler
Keyword(s):  
Kidney Diseases ◽  
Treatment Strategies ◽  
Blood Oxygen Level Dependent ◽  
Great Promise ◽  
Blood Oxygen Level ◽  
Bold Mri ◽  
Contrast Enhanced ◽  
Radiologic Imaging ◽  
Wide Range ◽  
New Treatment

Kidney diseases can be caused by a wide range of genetic, hemodynamic, toxic, infectious, and autoimmune factors. The diagnosis of kidney disease usually involves the biochemical analysis of serum and blood, but these tests are often insufficiently sensitive or specific to make a definitive diagnosis. Although radiologic imaging currently has a limited role in the evaluation of most kidney diseases, several new imaging methods hold great promise for improving our ability to non-invasively detect structural, functional, and molecular changes within the kidney. New methods, such as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and blood oxygen level-dependent (BOLD) MRI, allow functional imaging of the kidney. The use of novel contrast agents, such as microbubbles and nanoparticles, allows the detection of specific molecules in the kidney. These methods could greatly advance our ability to diagnose disease and also to safely monitor patients over time. This could improve the care of individual patients, and it could also facilitate the evaluation of new treatment strategies.

Characterizing blood oxygen level-dependent (BOLD) response following in-magnet quadriceps exercise

2014 ◽  
Vol 28 (3) ◽  
pp. 271-278 ◽  
Author(s):  
Jessica E. Caterini ◽  
Alyaa H. Elzibak ◽  
Emilie Jean St. Michel ◽  
Brian W. McCrindle ◽  
Andrew N. Redington ◽  
...  
Keyword(s):  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Bold Response ◽  
Oxygen Level ◽  
Blood Oxygen Level
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