scholarly journals Functional Neuroimaging in Rodents Using Cerebral Blood Flow SPECT

2020 ◽  
Vol 8 ◽  
Author(s):  
Anja M. Oelschlegel ◽  
Jürgen Goldschmidt
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Neuroimaging

scholarly journals Isn't functional neuroimaging all about Ca2+ signaling in astrocytes?

2015 ◽  
Vol 114 (3) ◽  
pp. 1353-1356 ◽  
Author(s):  
Mauro DiNuzzo
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Neuroimaging ◽  
Local Cerebral Blood Flow ◽  
The Past ◽  
Cereb Blood Flow ◽  
Intracellular Ca ◽  
Flow Through ◽  
Experimental Findings ◽  
Paradigm Shifting

Extensive research over the past decades about the multifaceted roles of brain astrocytes led to the suggestion that the signals observed with functional neuroimaging might primarily reflect astrocytic rather than neuronal activity. The basis for this paradigm-shifting concept was the evidence for an involvement of astrocytes in the control of local cerebral blood flow through intracellular Ca2+ signaling. In this Neuro Forum, I discuss new important experimental findings obtained by Jego et al. (Jego P, Pacheco-Torres J, Araque A, Canals S. J Cereb Blood Flow Metab 34: 1599–1603, 2014) as well as other closely related studies published recently, prompting a dismissal of substantial astrocytic contribution in functional neuroimaging.

The use of cerebral blood flow as an index of neuronal activity in functional neuroimaging: experimental and pathophysiological considerations

2000 ◽  
Vol 20 (3-4) ◽  
pp. 215-224 ◽  
Author(s):  
Willy Gsell ◽  
Christelle De Sadeleer ◽  
Yannick Marchalant ◽  
Eric T. MacKenzie ◽  
Pascale Schumann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Neuronal Activity ◽  
Functional Neuroimaging

scholarly journals Stimulation-induced increases in cerebral blood flow and local capillary vasoconstriction depend on conducted vascular responses

2018 ◽  
Vol 115 (25) ◽  
pp. E5796-E5804 ◽  
Author(s):  
Changsi Cai ◽  
Jonas C. Fordsmann ◽  
Sofie H. Jensen ◽  
Bodil Gesslein ◽  
Micael Lønstrup ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Neuroimaging ◽  
Active Role ◽  
Second Order ◽  
Synaptic Activity ◽  
Vascular Responses ◽  
Two Photon Microscopy ◽  
Cerebrovascular Function

Functional neuroimaging, such as fMRI, is based on coupling neuronal activity and accompanying changes in cerebral blood flow (CBF) and metabolism. However, the relationship between CBF and events at the level of the penetrating arterioles and capillaries is not well established. Recent findings suggest an active role of capillaries in CBF control, and pericytes on capillaries may be major regulators of CBF and initiators of functional imaging signals. Here, using two-photon microscopy of brains in living mice, we demonstrate that stimulation-evoked increases in synaptic activity in the mouse somatosensory cortex evokes capillary dilation starting mostly at the first- or second-order capillary, propagating upstream and downstream at 5–20 µm/s. Therefore, our data support an active role of pericytes in cerebrovascular control. The gliotransmitter ATP applied to first- and second-order capillaries by micropipette puffing induced dilation, followed by constriction, which also propagated at 5–20 µm/s. ATP-induced capillary constriction was blocked by purinergic P2 receptors. Thus, conducted vascular responses in capillaries may be a previously unidentified modulator of cerebrovascular function and functional neuroimaging signals.

scholarly journals Hemodynamic Changes after Visual Stimulation and Breath Holding Provide Evidence for an Uncoupling of Cerebral Blood Flow and Volume from Oxygen Metabolism

2008 ◽  
Vol 29 (1) ◽  
pp. 176-185 ◽  
Author(s):  
Manus J Donahue ◽  
Robert D Stevens ◽  
Michiel de Boorder ◽  
James J Pekar ◽  
Jeroen Hendrikse ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cerebral Blood Volume ◽  
Visual Stimulation ◽  
Functional Neuroimaging ◽  
Oxygen Metabolism ◽  
Blood Oxygenation ◽  
Breath Holding ◽  
Breath Hold ◽  
Bold Signal

Functional neuroimaging is most commonly performed using the blood-oxygenation-level-dependent (BOLD) approach, which is sensitive to changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and the cerebral metabolic rate of oxygen (CMRO2). However, the precise mechanism by which neuronal activity elicits a hemodynamic response remains controversial. Here, visual stimulation (14 secs flashing checkerboard) and breath-hold (4 secs exhale + 14 secs breath hold) experiments were performed in alternating sequence on healthy volunteers using BOLD, CBV-weighted, and CBF-weighted fMRI. After visual stimulation, the BOLD signal persisted for 33 ± 5 secs (n = 9) and was biphasic with a negative component (undershoot), whereas CBV and CBF returned to baseline without an undershoot at 20 ± 5 and 20 ± 3 secs, respectively. After breath hold, the BOLD signal returned to baseline (23 ±7 secs) at the same time ( P < 0.05) as CBV (21 ± 6 secs) and CBF (18 ±3 secs), without a poststimulus undershoot. These data suggest that the BOLD undershoot after visual activation reflects a persistent increase in CMRO2. These observations support the view that CBV and CBF responses elicited by neuronal activation are not necessarily coupled to local tissue metabolism.

scholarly journals Early Temporal Characteristics of Cerebral Blood Flow and Deoxyhemoglobin Changes during Somatosensory Stimulation

2000 ◽  
Vol 20 (1) ◽  
pp. 201-206 ◽  
Author(s):  
Afonso C. Silva ◽  
Sang-Pil Lee ◽  
Costantino Iadecola ◽  
Seong-Gi Kim
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Oxygen Consumption ◽  
Time Course ◽  
Functional Neuroimaging ◽  
Onset Time ◽  
Blood Oxygenation ◽  
High Temporal Resolution ◽  
Somatosensory Stimulation ◽  
Temporal Characteristics

The close correspondence between neural activity in the brain and cerebral blood flow (CBF) forms the basis for modern functional neuroimaging methods. Yet, the temporal characteristics of hemodynamic changes induced by neuronal activity are not well understood. Recent optical imaging observations of the time course of deoxyhemoglobin (HbR) and oxyhemoglobin have suggested that increases in oxygen consumption after neuronal activation occur earlier and are more spatially localized than the delayed and more diffuse CBF response. Deoxyhemoglobin can be detected by blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI). In the present study, the temporal characteristics of CBF and BOLD changes elicited by somatosensory stimulation in rat were investigated by high-field (9.4 T) MRI. With use of high-temporal-resolution fMRI, it was found that the onset time of the CBF response in the somatosensory cortex was 0.6 ± 0.4 seconds (n = 10). The CBF changes occurred significantly earlier than changes in HbR concentration, which responded after 1.1 ± 0.3 seconds. Furthermore, no early increases in HbR (early negative BOLD signal changes) were observed. These findings argue against the occurrence of an early loss of hemoglobin oxygenation that precedes the rise in CBF and suggest that CBF and oxygen consumption increases may be dynamically coupled in this animal model of neural activation.

scholarly journals Precapillary sphincters control cerebral blood flow

2019 ◽  
Author(s):  
Søren Grubb ◽  
Changsi Cai ◽  
Bjørn O. Hald ◽  
Lila Khennouf ◽  
Jonas Fordsmann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Neuroimaging ◽  
Smooth Muscle Actin ◽  
Cell Activity ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Brain Capillary ◽  
Blood Flow Control ◽  
Precapillary Sphincter

AbstractActive nerve cells produce and release vasodilators that increase their energy supply by dilating local blood vessels, a mechanism termed neurovascular coupling, which is the basis of the BOLD (blood-oxygen-level-dependent) functional neuroimaging signals. We here reveal a unique mechanism for cerebral blood flow control, a precapillary sphincter at the transition between the penetrating arteriole and the first capillary that links blood flow in capillaries to the arteriolar inflow. Large NG2-positive cells, containing smooth muscle actin, encircle the sphincters and rises in nerve cell activity cause astrocyte and neuronal Ca2+ rises that correlate to dilation and shortening of the sphincter concomitant with substantial increases in the RBC flux. Global ischemia and cortical spreading depolarization constrict sphincters and cause vascular trapping of blood cells. These results reveal precapillary sphincters as bottlenecks for brain capillary blood flow.

scholarly journals Developmental coupling of cerebral blood flow and fMRI fluctuations in youth

2021 ◽  
Author(s):  
Erica B Baller ◽  
Alessandra M Valcarcel ◽  
Azeez Adebimpe ◽  
Aaron Alexander-Bloch ◽  
Zaixu Cui ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Executive Function ◽  
Psychiatric Symptoms ◽  
Functional Neuroimaging ◽  
Generalized Additive Models ◽  
Low Frequency ◽  
Additive Models ◽  
Frontoparietal Network ◽  
The Brain

To support brain development during youth, the brain must balance energy delivery and consumption. Previous studies in adults have demonstrated high coupling between cerebral blood flow and brain function as measured using functional neuroimaging, but how this relationship evolves over adolescence is unknown. To address this gap, we studied a sample of 831 children and adolescents (478 females, ages 8-22) from the Philadelphia Neurodevelopmental Cohort who were scanned at 3T with both arterial spin labeled (ASL) MRI and resting-state functional MRI (fMRI). Local coupling between cerebral blood flow (CBF, from ASL) and the amplitude of low frequency fluctuations (ALFF, from fMRI) was first quantified using locally weighted regressions on the cortical surface. We then used generalized additive models to evaluate how CBF-ALFF coupling was associated with age, sex, and executive function. Enrichment of effects within canonical functional networks was evaluated using spin-based permutation tests. Our analyses revealed tight CBF-ALFF coupling across the brain. Whole-brain CBF-ALFF coupling decreased with age, largely driven by coupling decreases in the inferior frontal cortex, precuneus, visual cortex, and temporoparietal cortex (pfdr <0.05). Females had stronger coupling in the frontoparietal network than males (pfdr <0.05). Better executive function was associated with decreased coupling in the somatomotor network (pfdr <0.05). Overall, we found that CBF-ALFF coupling evolves in development, differs by sex, and is associated with individual differences in executive function. Future studies will investigate relationships between maturational changes in CBF-ALFF coupling and the presence of psychiatric symptoms in youth.

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