scholarly journals Vascular Action as the Primary Mechanism of Cognitive Effects of Cholinergic, CNS-Acting Drugs, a Rat phMRI BOLD Study

2014 ◽  
Vol 34 (6) ◽  
pp. 995-1000 ◽  
Author(s):  
Pál Kocsis ◽  
István Gyertyán ◽  
János Éles ◽  
Judit Laszy ◽  
Nikolett Hegedüs ◽  
...  
Keyword(s):  
Cognitive Deficits ◽  
Cholinesterase Inhibitor ◽  
Blood Oxygen Level Dependent ◽  
Cognitive Effects ◽  
Cerebral Vasculature ◽  
Blood Oxygen Level ◽  
Negative Bold ◽  
Cns Effects ◽  
The Brain ◽  
Impaired Circulation

Concordant results of functional magnetic resonance imaging (fMRI) and behavioral tests prove that some non-blood-brain barrier-penetrating drugs produce robust central nervous system (CNS) effects. The anticholinergic scopolamine interferes with learning when tested in rats, which coincides with a negative blood-oxygen-level-dependent (BOLD) change in the prefrontal cortex (PFC) as demonstrated by fMRI. The peripherally acting butylscopolamine also evokes a learning deficit in a water-labyrinth test and provokes a negative BOLD signal in the PFC. Donepezil—a highly CNS-penetrating Cholinesterase inhibitor—prevents the negative BOLD and cognitive deficits regardless whether the provoking agent is scopolamine or butylscopolamine. Interestingly, the non-BBB-penetrating Cholinesterase inhibitor neostigmine also prevents or substantially inhibits those cognitive and fMRI changes. Intact cerebral blood flow and optimal metabolism are crucial for the normal functioning of neurons and other cells in the brain. Drugs that are not BBB penetrating yet act on the CNS highlight the importance of unimpaired circulation, and point to the cerebral vasculature as a primary target for drug action in diseases where impaired circulation and consequently suboptimal energy metabolism are followed by upstream pathologic events.

scholarly journals Measurement of CMRO2 and its relationship with CBF in hypoxia with an extended calibrated BOLD method

2019 ◽  
Vol 40 (10) ◽  
pp. 2066-2080
Author(s):  
Yaoyu Zhang ◽  
Yayan Yin ◽  
Huanjie Li ◽  
Jia-Hong Gao
Keyword(s):  
Cerebral Blood Volume ◽  
Pulse Sequence ◽  
Blood Oxygen Level Dependent ◽  
Extended Model ◽  
Brain Health ◽  
Blood Oxygen Level ◽  
Oxygen Conditions ◽  
Health And Disease ◽  
The Brain ◽  
Mild Hypoxia

Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) are physiological parameters that not only reflect brain health and disease but also jointly contribute to blood oxygen level-dependent (BOLD) signals. Nevertheless, unsolved issues remain concerning the CBF–CMRO2 relationship in the working brain under various oxygen conditions. In particular, the CMRO2 responses to functional tasks in hypoxia are less studied. We extended the calibrated BOLD model to incorporate CMRO2 measurements in hypoxia. The extended model, which was cross-validated with a multicompartment BOLD model, considers the influences of the reduced arterial saturation level and increased baseline cerebral blood volume (CBV) and deoxyhemoglobin concentration on the changes of BOLD signals in hypoxia. By implementing a pulse sequence to simultaneously acquire the CBV-, CBF- and BOLD-weighted signals, we investigated the effects of mild hypoxia on the CBF and CMRO2 responses to graded visual stimuli. Compared with normoxia, mild hypoxia caused significant alterations in both the amplitude and the trend of the CMRO2 responses but did not impact the corresponding CBF responses. Our observations suggested that the flow-metabolism coupling strategies in the brain during mild hypoxia were different from those during normoxia.

Interhemispheric Integration at Different Spatial Scales: The Evidence From EEG Coherence and fMRI

2006 ◽  
Vol 96 (1) ◽  
pp. 259-275 ◽  
Author(s):  
Maria G. Knyazeva ◽  
Eleonora Fornari ◽  
Reto Meuli ◽  
Philippe Maeder
Keyword(s):  
Spatial Scales ◽  
Neural Substrates ◽  
Blood Oxygen Level Dependent ◽  
Specific Information ◽  
Eeg Coherence ◽  
Blood Oxygen Level ◽  
Spatial Frequencies ◽  
Collateral Sulcus ◽  
Gestalt Grouping ◽  
The Brain

The early visual system processes different spatial frequencies (SFs) separately. To examine where in the brain the scale-specific information is integrated, we mapped the neural assemblies engaged in interhemispheric coupling with electroencephalographic (EEG) coherence and blood-oxygen-level dependent (BOLD) signal. During similar EEG and functional magnetic resonance imaging (fMRI) experiments, our subjects viewed centrally presented bilateral gratings of different SF (0.25–8.0 cpd), which either obeyed Gestalt grouping rules (iso-oriented, IG) or violated them (orthogonally oriented, OG). The IG stimuli (0.5–4.0 cpd) synchronized EEG at discrete beta frequencies (beta1, beta2) and increased BOLD (0.5 and 2.0 cpd tested) in ventral (around collateral sulcus) and dorsal (parieto-occipital fissure) regions compared with OG. At both SF, the beta1 coherence correlated with the ventral activations, whereas the beta2 coherence correlated with the dorsal ones. Thus distributed neural substrates mediated interhemispheric integration at single SF. The relative impact of the ventral versus dorsal networks was modulated by the SF of the stimulus.

Differential neural correlates of reciprocal activation and cocontraction control in dorsal and ventral premotor cortices

2012 ◽  
Vol 107 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Masahiko Haruno ◽  
Gowrishankar Ganesh ◽  
Etienne Burdet ◽  
Mitsuo Kawato
Keyword(s):  
Brain Activity ◽  
Premotor Cortex ◽  
Neural Correlates ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Dorsal Premotor Cortex ◽  
Blood Oxygen Level ◽  
Efficient Control ◽  
Dependent Activity ◽  
The Brain

Efficient control of reciprocal activation and cocontraction of the muscles are critical to perform skillful actions with suitable force and impedance. However, it remains unclear how the brain controls force and impedance while recruiting the same set of muscles as actuators. Does control take place at the single muscle level leading to force and impedance, or are there higher-order centers dedicated to controlling force and impedance? We addressed this question using functional MRI during voluntary isometric wrist contractions with online electromyogram feedback. Comparison of the brain activity between the conditions requiring control of either wrist torque or cocontraction demonstrates that blood oxygen level-dependent activity in the caudo-dorsal premotor cortex (PMd) correlates well with torque, whereas the activity in the ventral premotor cortex (PMv) correlates well with the level of cocontraction. This suggests distinct roles of the PMd and PMv in the voluntary control of reciprocal activation and cocontraction of muscles, respectively.

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.

scholarly journals Resting state fMRI in pre-surgical brain mapping. Literature review

2018 ◽  
pp. 6-13 ◽  
Author(s):  
A. S. Smirnov ◽  
M. G. Sharaev ◽  
T. V. Melnikova-Pitskhelauri ◽  
V. Yu. Zhukov ◽  
A. E. Bikanov ◽  
...  
Keyword(s):  
Brain Mapping ◽  
Resting State ◽  
Preoperative Planning ◽  
Clinical Information ◽  
Complete Information ◽  
Resting State Fmri ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Spontaneous Fluctuations ◽  
The Brain

Today, functional magnetic resonance imaging (fMRI) allows to plan surgery based on the topography of functionally important areas of the human brain cortex and tumor. This method can complement the surgical strategy with significant clinical information. The stimulus-dependent fMRI with motor and language paradigms is generally used for preoperative planning. The study outcome depends on the patient's ability to perform tasks paradigm, which is broken in brain tumors. In an attempt to overcome this problem, resting-state fMRI (rs-fMRI) is used for brain mapping. Rs-fMRI is based on the measurement of spontaneous fluctuations of the BOLD signal (blood oxygen level-dependent), representing the functional structure of the brain. In contrast to stimulus-dependent fMRI, rs-fMRI provides more complete information about functional architecture of the brain. rs-fMRI is used in conditions where the results of stimulusdependent fMRI may be falsely positive or in the absence of the possibility of its implementation. In aggregate, both methods significantly expand the efficiency and specificity of preoperative planning.

scholarly journals The processing of color preference in the brain

2018 ◽  
Author(s):  
Chris Racey ◽  
Anna Franklin ◽  
Chris M. Bird
Keyword(s):  
Brain Activity ◽  
Blood Oxygen Level Dependent ◽  
Color Preference ◽  
Blood Oxygen Level ◽  
Neural Basis ◽  
Color Preferences ◽  
Subjective Value ◽  
Value Judgements ◽  
Automatic Encoding ◽  
The Brain

AbstractDecades of research has established that humans have preferences for some colors (e.g., blue) and a dislike of others (e.g., dark chartreuse), with preference varying systematically with variation in hue (e.g., Hurlbert & Owen, 2015). Here, we used functional MRI to investigate why humans have likes and dislikes for simple patches of color, and to understand the neural basis of preference, aesthetics and value judgements more generally. We looked for correlations of a behavioural measure of color preference with the blood oxygen level-dependent (BOLD) response when participants performed an irrelevant orientation judgement task on colored squares. A whole brain analysis found a significant correlation between BOLD activity and color preference in the posterior midline cortex (PMC), centred on the precuneus but extending into the adjacent posterior cingulate and cuneus. These results demonstrate that brain activity is modulated by color preference, even when such preferences are irrelevant to the ongoing task the participants are engaged. They also suggest that color preferences automatically influence our processing of the visual world. Interestingly, the effect in the PMC overlaps with regions identified in neuroimaging studies of preference and value judgements of other types of stimuli. Therefore, our findings extends this literature to show that the PMC is related to automatic encoding of subjective value even for basic visual features such as color.

Low-frequency blood oxygen level-dependent fluctuations in the brain white matter: more than just noise

2017 ◽  
Vol 62 (9) ◽  
pp. 656-657 ◽  
Author(s):  
Gong-Jun Ji ◽  
Wei Liao ◽  
Fang-Fang Chen ◽  
Lei Zhang ◽  
Kai Wang
Keyword(s):  
White Matter ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Brain White Matter ◽  
The Brain
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