scholarly journals The influence of non-neural factors on BOLD signal magnitude

2021 ◽  
Author(s):  
Jan W. Kurzawski ◽  
Omer Faruk Gulban ◽  
Keith W. Jamison ◽  
Jonathan Winawer ◽  
Kendrick Kay
Keyword(s):  
Cortical Thickness ◽  
Neural Activity ◽  
Correction Method ◽  
Blood Oxygen Level Dependent ◽  
Response Magnitude ◽  
Bold Response ◽  
Vertical Meridian ◽  
Percent Signal Change ◽  
Surprising Effect ◽  
Bold Responses

To what extent is the size of the blood-oxygen-level-dependent (BOLD) response influenced by factors other than neural activity? In a re-analysis of three neuroimaging datasets, we find large systematic inhomogeneities in the BOLD response magnitude in primary visual cortex (V1): stimulus-evoked BOLD responses, expressed in units of percent signal change, are up to 50% larger along the representation of the horizontal meridian than the vertical meridian. To assess whether this surprising effect can be interpreted as differences in local neural activity, we quantified several factors that potentially contribute to the size of the BOLD response. We find strong relationships between BOLD response magnitude and cortical thickness, cortical curvature, and the presence of large veins. These relationships are consistently found across subjects and suggest that variation in BOLD response magnitudes across cortical locations reflects, in part, differences in anatomy and vascularization. To compensate for these factors, we implement a regression-based correction method and show that after correction, BOLD responses become more homogeneous across V1. The correction reduces the horizontal/vertical difference by about half, indicating that some of the difference is likely not due to neural activity differences. Additionally, we find that while the cerebral sinuses overlap with the vertical meridian representation in V1, they do not explain the observed horizontal/vertical difference. We conclude that interpretation of variation in BOLD response magnitude across cortical locations should consider the influence of the potential confounding factors of cortical thickness, curvature, and vascularization.

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.

scholarly journals Quantitative relations between BOLD responses, cortical energetics, and impulse firing

2018 ◽  
Vol 119 (3) ◽  
pp. 979-989 ◽  
Author(s):  
M. R. Bennett ◽  
L. Farnell ◽  
W. G. Gibson
Keyword(s):  
Neural Activity ◽  
Blood Oxygen Level Dependent ◽  
Bold Signal ◽  
Neural Firing ◽  
Functional Magnetic Resonance ◽  
Blood Oxygen Level ◽  
Baseline Activity ◽  
Bold Responses ◽  
Negative Bold ◽  
Quantitative Account

The blood oxygen level-dependent (BOLD) functional magnetic resonance imaging signal arises as a consequence of changes in blood flow and oxygen usage that in turn are modulated by changes in neural activity. Much attention has been given to both theoretical and experimental aspects of the energetics but not to the neural activity. Here we identify the best energetic theory for the steady-state BOLD signal on the basis of correct predictions of experimental observations. This theory is then used, together with the recently determined relationship between energetics and neural activity, to predict how the BOLD signal changes with activity. Unlike existing treatments, this new theory incorporates a nonzero baseline activity in a completely consistent way and is thus able to account for both sustained positive and negative BOLD signals. We also show that the increase in BOLD signal for a given increase in activity is significantly smaller the larger the baseline activity, as is experimentally observed. Furthermore, the decline of the positive BOLD signal arising from deeper cortical laminae in response to an increase in neural firing is shown to arise as a consequence of the larger baseline activity in deeper laminae. Finally, we provide quantitative relations integrating BOLD responses, energetics, and impulse firing, which among other predictions give the same results as existing theories when the baseline activity is zero. NEW & NOTEWORTHY We use a recently established relation between energetics and neural activity to give a quantitative account of BOLD dependence on neural activity. The incorporation of a nonzero baseline neural activity accounts for positive and negative BOLD signals, shows that changes in neural activity give BOLD changes that are smaller the larger the baseline, and provides a basis for the observed inverse relation between BOLD responses and the depth of cortical laminae giving rise to them.

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.

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 Association Between Brain Activation and Functional Connectivity

2018 ◽  
Vol 29 (5) ◽  
pp. 1984-1996 ◽  
Author(s):  
Dardo Tomasi ◽  
Nora D Volkow
Keyword(s):  
Functional Connectivity ◽  
Brain Activity ◽  
Low Frequency ◽  
Brain Activation ◽  
Blood Oxygen Level Dependent ◽  
Common Source ◽  
Functional Connectivity Density ◽  
Density Mapping ◽  
Human Connectome Project ◽  
Bold Responses

Abstract The origin of the “resting-state” brain activity recorded with functional magnetic resonance imaging (fMRI) is still uncertain. Here we provide evidence for the neurovascular origins of the amplitude of the low-frequency fluctuations (ALFF) and the local functional connectivity density (lFCD) by comparing them with task-induced blood-oxygen level dependent (BOLD) responses, which are considered a proxy for neuronal activation. Using fMRI data for 2 different tasks (Relational and Social) collected by the Human Connectome Project in 426 healthy adults, we show that ALFF and lFCD have linear associations with the BOLD response. This association was significantly attenuated by a novel task signal regression (TSR) procedure, indicating that task performance enhances lFCD and ALFF in activated regions. We also show that lFCD predicts BOLD activation patterns, as was recently shown for other functional connectivity metrics, which corroborates that resting functional connectivity architecture impacts brain activation responses. Thus, our findings indicate a common source for BOLD responses, ALFF and lFCD, which is consistent with the neurovascular origin of local hemodynamic synchrony presumably reflecting coordinated fluctuations in neuronal activity. This study also supports the development of task-evoked functional connectivity density mapping.

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 Behavioural cue reactivity to alcohol and non-alcohol-related stimuli among individuals with severe alcohol use disorder: an fMRI study with a visual task

2020 ◽  
Author(s):  
Shou Fukushima ◽  
Hironori Kuga ◽  
Naoya Oribe ◽  
Takeo Mutou ◽  
Takefumi Yuzuriha ◽  
...  
Keyword(s):  
Alcohol Use ◽  
Alcohol Use Disorder ◽  
Brain Activity ◽  
Cue Reactivity ◽  
Drinking Behavior ◽  
Significant Negative Correlation ◽  
Blood Oxygen Level Dependent ◽  
Posterior Cingulate Cortex ◽  
Alcoholic Beverages ◽  
Bold Responses

AbstractPatients with alcohol use disorder (AUD) have difficulties controlling alcohol cravings and thus exhibit increased use and earlier relapse. Although patients tend to respond more strongly to alcohol-related images compared with non-alcohol-related images, few researchers examined the factors that modulate cravings. Here, we examined whole-brain blood oxygen level-dependent (BOLD) responses to behavioural cues in individuals with AUD and healthy controls (HCs). The participants included 24 patients with severe AUD and 15 HCs. We presented four beverage images (juice, drinking juice, sake, and drinking sake) and compared participant BOLD responses between the two groups. Multiple comparisons revealed that the AUD group had lower BOLD responses compared with the HC group to images of drinking juice in the left precuneus (p = 0.036) and the left posterior cingulate cortex (PCC) (p = 0.044) and higher BOLD responses to images of drinking sake in the left PCC (p = 0.044). Furthermore, compared to the HCs, the AUD patients had decreased BOLD responses associated with cue reactivity to drinking juice in the left precuneus during the period from 15 to 18 s (p = 0.004, df = 37) and 18 to 21 s (p = 0.002, df = 37). Using the Spearman correlation, we found a significant negative correlation between BOLD responses in the left PCC of the AUD patients and Mini–Mental State Examination (MMSE) scores (r = −0.619, p = 0.001). Our findings suggest that HCs and severe AUD patients differ in their responses not to images of alcoholic beverages but those related to alcohol drinking behavior. Thus, these patients appear to have different patterns of brain activity. This information may aid clinicians in developing treatments for patients with AUD.

scholarly journals Exploring Cortical Attentional System by Using fMRI during a Continuous Perfomance Test

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
M. G. Tana ◽  
E. Montin ◽  
S. Cerutti ◽  
A. M. Bianchi
Keyword(s):  
Performance Test ◽  
Continuous Performance Test ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Brain Network ◽  
Anterior Cingulate ◽  
Visual Object ◽  
Bold Response ◽  
Object Processing ◽  
The Right

Functional magnetic resonance imaging (fMRI) was performed in eight healthy subjects to identify the localization, magnitude, and volume extent of activation in brain regions that are involved in blood oxygen level-dependent (BOLD) response during the performance of Conners' Continuous Performance Test (CPT). An extensive brain network was activated during the task including frontal, temporal, and occipital cortical areas and left cerebellum. The more activated cluster in terms of volume extent and magnitude was located in the right anterior cingulate cortex (ACC). Analyzing the dynamic trend of the activation in the identified areas during the entire duration of the sustained attention test, we found a progressive decreasing of BOLD response probably due to a habituation effect without any deterioration of the performances. The observed brain network is consistent with existing models of visual object processing and attentional control and may serve as a basis for fMRI studies in clinical populations with neuropsychological deficits in Conners' CPT performance.

Common Neural Correlates of Intertemporal Choices and Intelligence in Adolescents

2015 ◽  
Vol 27 (2) ◽  
pp. 387-399 ◽  
Author(s):  
Stephan Ripke ◽  
Thomas Hübner ◽  
Eva Mennigen ◽  
Kathrin U. Müller ◽  
Shu-Chen Li ◽  
...  
Keyword(s):  
Intertemporal Choice ◽  
Inferior Frontal Gyrus ◽  
Temporal Discounting ◽  
Neural Correlates ◽  
Bold Response ◽  
Decision Network ◽  
A Value ◽  
Bold Responses ◽  
Choice Consistency ◽  
Intertemporal Choices

Converging behavioral evidence indicates that temporal discounting, measured by intertemporal choice tasks, is inversely related to intelligence. At the neural level, the parieto-frontal network is pivotal for complex, higher-order cognitive processes. Relatedly, underrecruitment of the pFC during a working memory task has been found to be associated with steeper temporal discounting. Furthermore, this network has also been shown to be related to the consistency of intertemporal choices. Here we report an fMRI study that directly investigated the association of neural correlates of intertemporal choice behavior with intelligence in an adolescent sample (n = 206; age 13.7–15.5 years). After identifying brain regions where the BOLD response during intertemporal choice was correlated with individual differences in intelligence, we further tested whether BOLD responses in these areas would mediate the associations between intelligence, the discounting rate, and choice consistency. We found positive correlations between BOLD response in a value-independent decision network (i.e., dorsolateral pFC, precuneus, and occipital areas) and intelligence. Furthermore, BOLD response in a value-dependent decision network (i.e., perigenual ACC, inferior frontal gyrus, ventromedial pFC, ventral striatum) was positively correlated with intelligence. The mediation analysis revealed that BOLD responses in the value-independent network mediated the association between intelligence and choice consistency, whereas BOLD responses in the value-dependent network mediated the association between intelligence and the discounting rate. In summary, our findings provide evidence for common neural correlates of intertemporal choice and intelligence, possibly linked by valuation as well as executive functions.

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