scholarly journals Relationship of Spikes, Synaptic Activity, and Local Changes of Cerebral Blood Flow

2001 ◽  
Vol 21 (12) ◽  
pp. 1367-1383 ◽  
Author(s):  
Martin Lauritzen
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Functional Anatomy ◽  
Glucose Consumption ◽  
Afferent Input ◽  
Spike Rate ◽  
Synaptic Activity ◽  
Vascular Response ◽  
Hemodynamic Changes ◽  
The Brain

The coupling of electrical activity in the brain to changes in cerebral blood flow (CBF) is of interest because hemodynamic changes are used to track brain function. Recent studies, especially those investigating the cerebellar cortex, have shown that the spike rate in the principal target cell of a brain region (i.e. the efferent cell) does not affect vascular response amplitude. Subthreshold integrative synaptic processes trigger changes in the local microcirculation and local glucose consumption. The spatial specificity of the vascular response on the brain surface is limited because of the functional anatomy of the pial vessels. Within the cortex there is a characteristic laminar flow distribution, the largest changes of which are observed at the depth of maximal synaptic activity (i.e. layer IV) for an afferent input system. Under most conditions, increases in CBF are explained by activity in postsynaptic neurons, but presynaptic elements can contribute. Neurotransmitters do not mediate increases in CBF that are triggered by the concerted action of several second messenger molecules. It is important to distinguish between effective synaptic inhibition and deactivation that increase and decrease CBF and glucose consumption, respectively. In summary, hemodynamic changes evoked by neuronal activity depend on the afferent input function (i.e. all aspects of presynaptic and postsynaptic processing), but are totally independent of the efferent function (i.e., the spike rate of the same region). Thus, it is not possible to conclude whether the output level of activity of a region is increased based on brain maps that use blood-flow changes as markers.

Vorläufige Ergebnisse von 99mTc-HMPAO-SPECT-Untersuchungen bei endogenen Psychosen

1989 ◽  
Vol 28 (03) ◽  
pp. 88-91
Author(s):  
J. Schröder ◽  
H. Henningsen ◽  
H. Sauer ◽  
P. Georgi ◽  
K.-R. Wilhelm
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Regions Of Interest ◽  
Post Mortem ◽  
Regional Cerebral Blood ◽  
Hmpao Spect ◽  
Endogenous Psychoses ◽  
The Brain ◽  
99Mtc Hmpao

18 psychopharmacologically treated patients (7 schizophrenics, 5 schizoaffectives, 6 depressives) were studied using 99mTc-HMPAO-SPECT of the brain. The regional cerebral blood flow was measured in three transversal sections (infra-/supraventricular, ventricular) within 6 regions of interest (ROI) respectively (one frontal, one parietal and one occipital in each hemisphere). Corresponding ROIs of the same section in each hemisphere were compared. In the schizophrenics there was a significantly reduced perfusion in the left frontal region of the infraventricular and ventricular section (p < 0.02) compared with the data of the depressives. The schizoaffectives took an intermediate place. Since the patients were treated with psychopharmaca, the result must be interpreted cautiously. However, our findings seem to be in accordance with post-mortem-, CT- and PET-studies presented in the literature. Our results suggest that 99mTc-HMPAO-SPECT may be helpful in finding cerebral abnormalities in endogenous psychoses.

Neuroimaging in Drug Discovery and Development: Paradigms for Accelerating New Drug Availability

2001 ◽  
Vol 14 (5) ◽  
pp. 407-415
Author(s):  
John T. Metz ◽  
Malcolm D. Cooper ◽  
Terry F. Brown ◽  
Leann H. Kinnunen ◽  
Declan J. Cooper
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Glucose Metabolism ◽  
Phase Ii ◽  
New Drugs ◽  
Central Effects ◽  
Drug Discovery And Development ◽  
Psychological Tasks ◽  
The Brain ◽  
Phase Iv

The process of discovering and developing new drugs is complicated. Neuroimaging methods can facilitate this process. An analysis of the conceptual bases and practical limitations of different neuroimaging modalities reveals that each technique can best address different kinds of questions. Radioligand studies are well suited to preclinical and Phase II questions when a compound is known or suspected to affect well-understood mechanisms; they are also useful in Phase IV to characterize effective agents. Cerebral blood flow studies can be extremely useful in evaluating the effects of a drug on psychological tasks (mostly in Phase IV). Glucose metabolism studies can answer the simplest questions about whether a compound affects the brain, where, and how much. Such studies are most useful in confirming central effects (preclinical and early clinical phases), in determining effective dose ranges (Phase II), and in comparing different drugs (Phase IV).

scholarly journals Local Cerebral Blood Flow and Glucose Consumption of Rats with Experimental Gliomas

1982 ◽  
Vol 2 (1) ◽  
pp. 25-32 ◽  
Author(s):  
K.-A. Hossmann ◽  
I. Niebuhr ◽  
M. Tamura
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Tumors ◽  
Brain Tissue ◽  
Glucose Utilization ◽  
Cell Clone ◽  
Tumor Development ◽  
Glucose Consumption ◽  
Contralateral Side ◽  
Opposite Hemisphere

Experimental brain tumors were produced in rats by intracerebral implantation of a neoplastic glial cell clone. Within 2–6 weeks, spherical brain tumors developed at the implantation site with a mean diameter of 6 mm. Local blood flow and local glucose utilization were measured under light barbiturate anesthesia by quantitative autoradiography in the tumor and peritumoral brain tissue. In solid parts of the tumor, blood flow was 57.8 ± 2.0 ml/100 g/min (mean ± SE), and glucose utilization was 87.2 ± 5.8 μmol/100 g/min, respectively. In necrotic regions, flow and glucose utilization were zero. In peritumoral brain tissue of the ipsilateral hemisphere blood flow was reduced by 13–23%, as compared to homologous regions of the opposite side, the greatest decrease being recorded in the ipsilateral thalamus. Flow in the opposite hemisphere was of the same order of magnitude as in normal control rats. Glucose consumption, in contrast, was distinctly reduced in both hemispheres: in the cortex and putamen, it was 40–50% lower than in normal controls. The following conclusions are drawn: (1) during tumor development the high glucose consumption in the tumor tissue is not coupled to an equal increase in blood flow; (2) peritumoral cerebral blood flow decreases on the ipsilateral but not on the contralateral side, and (3) the metabolic rate of glucose is distinctly inhibited in both hemispheres of tumor-bearing animals. The dissociation between blood flow and metabolism suggests that metabolic inhibition is not the consequence of a diaschitic depression of functional activity.

Surfactant Therapy and Intracranial Hemorrhage: Review of the Literature and Results of New Analyses

PEDIATRICS ◽  
1993 ◽  
Vol 92 (6) ◽  
pp. 775-786
Author(s):  
J. Harry Gunkel ◽  
Phillip L.C. Banks
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Birth Weight ◽  
Intracranial Hemorrhage ◽  
Incidence Rates ◽  
Surfactant Therapy ◽  
Controlled Study ◽  
Hemodynamic Changes ◽  
Increased Risk ◽  
Risk Of Hemorrhage

Background and objective. Surfactant replacement is a powerful therapy for newborns with respiratory distress syndrome, but limited observations suggest that alterations of cerebral blood flow can accompany the use of several available surfactants. An early European multicenter controlled study with beractant demonstrated an increased rate of intracranial hemorrhage in treated patients. Nine additional controlled studies were subsequently performed and included follow-up evaluations through 2 years adjusted age. This clinical experience provided a database of approximately 1700 infants to examine retrospectively for any relationship between surfactant therapy and intracranial hemorrhage. Methods. Cumulative incidence rates, hazard ratios, and 95% confidence intervals for intracranial hemorrhage were computed for each study and for appropriately pooled studies of similar design. Where an association between surfactant and the risk of intracranial hemorrhage was found, additional analyses were performed to attempt to identify intermediate physiologic events that might link administration of surfactant to the occurrence of intracranial hemorrhage. These analyses were guided by literature reports of hemodynamic changes observed in association with surfactant therapy. Results. During the controlled studies with beractant, treated newborns of 600 to 750 g birth weight were at higher risk for grades I and II intracranial hemorrhage than control newborns. There was no increased risk for grades III and IV hemorrhage among these newborns, nor was there increased risk of hemorrhage among any other patient groups. This finding did not result in increased morbidity for the affected patients; at 2 years adjusted age, they were not different from the control infants of 600 to 750 g birth weight. Retrospective examination of the database could not pinpoint the mechanism behind the finding, but it might have been related to changes in cerebral blood flow after surfactant uncompensated by ventilator management of oxygenation and ventilation. Conclusion. Surfactant therapy may set in motion hemodynamic changes that could predispose to intracranial hemorrhage in certain circumstances, but this can probably be compensated by careful management of oxygenation and ventilation. A relationship between surfactant therapy and intracranial hemorrhage is probably not isolated to any particular surfactant preparation or method of delivery; studies comparing surfactants have shown no differences in rates of intracranial hemorrhage.

Effects of Cytoflavin and Neuronol on Morphological Changes in the Brain and Survival of Rats with Ischemic Disturbances in Cerebral Blood Flow

2004 ◽  
Vol 137 (4) ◽  
pp. 411-414 ◽  
Author(s):  
V. V. Bulon ◽  
I. B. Krylova ◽  
N. R. Evdokimova ◽  
A. L. Kovalenko ◽  
L. E. Alekseeva ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Morphological Changes ◽  
The Brain

scholarly journals Use of 19F NMR Spectroscopy for Measurement of Cerebral Blood Flow: A Comparative Study Using Microspheres

1989 ◽  
Vol 9 (6) ◽  
pp. 886-891 ◽  
Author(s):  
David Barranco ◽  
Leslie N. Sutton ◽  
Sandra Florin ◽  
Joel Greenberg ◽  
Teresa Sinnwell ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Blood ◽  
Radioactive Microsphere ◽  
Low Concentrations ◽  
Cat Brain ◽  
Nmr Techniques ◽  
High Concentrations ◽  
Washout Curves ◽  
The Brain

19F NMR was used to determine washout curves of an inert, diffusible gas (CHF3) from the cat brain. The cerebral blood flow was estimated from a bi- or tri-phasic fit to the deconvoluted wash-out curve, using the Kety-Schmidt approach. Cerebral blood flow values determined by 19F NMR show the expected responsiveness to alterations in Paco2, but are approximately 28% lower than cerebral blood flow values determined simultaneously by radioactive microsphere techniques. High concentrations of CHF3 have little effect on intracranial pressure, mean arterial blood pressure or Paco2, but cause small changes in the blood flow to certain regions of the brain. We conclude that 19F NMR techniques utilizing low concentrations of CHF3 have potential for the noninvasive measurement of cerebral blood flow.

Vasodilation of cat cerebral arterioles by prostaglandins D2, E2, G2, and I2

1979 ◽  
Vol 237 (3) ◽  
pp. H381-H385 ◽  
Author(s):  
E. F. Ellis ◽  
E. P. Wei ◽  
H. A. Kontos
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Blood Pressure ◽  
Standard Error ◽  
Arterial Blood ◽  
Cerebral Arterioles ◽  
The Mean ◽  
Dose Dependent ◽  
The Brain

To determine the possible role that endogenously produced prostaglandins may play in the regulation of cerebral blood flow, the responses of cerebral precapillary vessels to prostaglandins (PG) D2, E2, G2, and I2 (8.1 X 10(-8) to 2.7 X 10(-5) M) were studied in cats equipped with cranial windows for direct observation of the microvasculature. Local application of PGs induced a dose-dependent dilation of large (greater than or equal to 100 microns) and small (less than 100 microns) arterioles with no effect on arterial blood pressure. The relative vasodilator potency was PGG2 greater than PGE2 greater than PGI2 greater than PGD2. With all PGs, except D2, the percent dilation of small arterioles was greater than the dilation of large arterioles. After application of prostaglandins in a concentration of 2.7 X 10(-5) M, the mean +/- standard error of the percent dilation of large and small arterioles was, respectively, 47.6 +/- 2.7 and 65.3 +/- 6.1 for G2, 34.1 +/- 2.0, and 53.6 +/- 5.5 for E2, 25.4 +/- 1.8, and 40.2 +/- 4.6 for I2, and 20.3 +/- 2.5 and 11.0 +/- 2.2 for D2. Because brain arterioles are strongly responsive to prostaglandins and the brain can synthesize prostaglandins from its large endogenous pool of prostaglandin precursor, prostaglandins may be important mediators of changes in cerebral blood flow under normal and abnormal conditions.

scholarly journals Effects of Gastric Bypass Surgery on the Brain; Simultaneous Assessment of Glucose Uptake, Blood Flow, Neural Activity and Cognitive Function during Normo- and Hypoglycemia

2021 ◽  
Author(s):  
Kristina E. Almby ◽  
Martin H. Lundqvist ◽  
Niclas Abrahamsson ◽  
Sofia Kvernby ◽  
Markus Fahlström ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gastric Bypass ◽  
Cerebral Blood Flow ◽  
Cognitive Function ◽  
Counterregulatory Hormones ◽  
Fdg Uptake ◽  
Post Surgery ◽  
Total Brain ◽  
Underlying Mechanisms ◽  
The Brain

While Roux-en-Y Gastric Bypass (RYGB) surgery in obese individuals typically improves glycemic control and prevents diabetes, it also frequently causes hypoglycemia. Previous work showed attenuated counter-regulatory responses following RYGB. The underlying mechanisms as well as the clinical consequences are unclear. <p>In this study, 11 non-diabetic subjects with severe obesity were investigated pre- and post-RYGB during hyperinsulinemic hypoglycemic clamps. Assessments were made of hormones, cognitive function, cerebral blood flow by arterial spin labeling, brain glucose metabolism by FDG PET and activation of brain networks by functional MRI. Post- vs pre-surgery, we found a general increase of cerebral blood flow but a decrease of total brain FDG uptake during normoglycemia. During hypoglycemia, there was a marked increase in total brain FDG uptake and this was similar for post- and pre-surgery, whereas hypothalamic FDG uptake was reduced. During hypoglycemia, attenuated responses of counterregulatory hormones and improvements in cognitive function were seen post-surgery. In early hypoglycemia, there was increased activation post- vs pre-surgery of neural networks in CNS regions implicated in glucose regulation such as the thalamus and hypothalamus. The results suggest adaptive responses of the brain that contribute to lowering of glycemia following RYGB, and the underlying mechanisms should be further elucidated.</p>

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