scholarly journals Changes in Cerebral Arterial, Tissue and Venous Oxygenation with Evoked Neural Stimulation: Implications for Hemoglobin-Based Functional Neuroimaging

2009 ◽  
Vol 30 (2) ◽  
pp. 428-439 ◽  
Author(s):  
Alberto L Vazquez ◽  
Mitsuhiro Fukuda ◽  
Michelle L Tasker ◽  
Kazuto Masamoto ◽  
Seong-Gi Kim
Keyword(s):  
Brain Function ◽  
Functional Neuroimaging ◽  
Sensory Stimulation ◽  
Average Diameter ◽  
Neural Stimulation ◽  
Blood Oxygen ◽  
Pial Arteries ◽  
Small Arteries ◽  
Arteries And Veins ◽  
Stimulation Of

Little is known regarding the changes in blood oxygen tension (PO2) with changes in brain function. This work aimed to measure the blood PO2 in surface arteries and veins as well as tissue with evoked somato-sensory stimulation in the anesthetized rat. Electrical stimulation of the forepaw induced average increases in blood flow of 44% as well as increases in the tissue PO2 of 28%. More importantly, increases in PO2 throughout pial arteries (resting diameters=59 to 129 μm) and pial veins (resting diameters=62 to 361 μm) were observed. The largest increases in vascular PO2 were observed in the small veins (from 33 to 40 mm Hg) and small arteries (from 78 to 88 mm Hg). The changes in oxygen saturation (SO2) were calculated and the largest increases were observed in small veins (Δ=+11%) while its increase in small arteries was small (Δ=+4%). The average diameter of arterial vessels was observed to increase by 4 to 6% while that of veins was not observed to change with evoked stimulation. These findings show that the increases in arterial PO2 contribute to the hyper-oxygenation of tissue and, mostly likely, also to the signal changes in hemoglobin-based functional imaging methods (e.g. BOLD fMRI).

scholarly journals Pial Vascular Behavior during Bilateral and Contralateral Cervical Sympathetic Stimulation

1986 ◽  
Vol 6 (3) ◽  
pp. 298-304 ◽  
Author(s):  
Ludwig M. Auer ◽  
Norio Ishiyama
Keyword(s):  
Sympathetic Stimulation ◽  
Bilateral Stimulation ◽  
Pial Arteries ◽  
Vascular Volume ◽  
Small Arteries ◽  
Contralateral Stimulation ◽  
Cranial Window ◽  
Cervical Sympathetic ◽  
Arteries And Veins ◽  
Hydrogen Clearance

The present study in cats investigates the effect of cervical sympathetic stimulation on changes of diameter of pial arteries and veins, CBF, and intracranial pressure (ICP) using the cranial window and hydrogen clearance techniques. During 20 min of bilateral stimulation, pial arteries maximally constricted by 12%, veins by 13–15%. While the constriction of the large arteries remained stable during the whole 20-min period of bilateral stimulation, small arteries escaped after some 2 min. A similar though weaker trend was noted for the veins. CBF was reduced at 2 min by 31%, and was not different from resting at 18 min. Contralateral stimulation for 20 min induced early constriction only in small arteries, while all other vessels remained more or less unreactive. This phenomenon is explained by interhemispheric arterial collaterals that bring sympathetic fibers mainly to small arteries contralaterally. ICP was lowered initially by 47 ± 12% during bilateral and by 23 ± 5% during contralateral stimulation. ICP escaped after 2 and 5 min during bilateral and contralateral stimulation, respectively, and even started to rise after some 10 min. From these data, it is concluded that the sympathoadrenergic system exerts a short-lasting protective effect upon cerebral vascular volume. Small arteries escape from constriction as a consequence of primarily myogenic counteraction of pial and intraparenchymal vessels, and probably additional metabolic dilatation of intraparenchymal vessels.

scholarly journals Electromagnetic stimulation in psychiatry

2001 ◽  
Vol 7 (3) ◽  
pp. 181-188 ◽  
Author(s):  
Klaus P. Ebmeier ◽  
Julia M. Lappin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Brain Imaging ◽  
Brain Function ◽  
Brain Research ◽  
Functional Neuroimaging ◽  
Memory Task ◽  
Functional Brain Imaging ◽  
Functional Brain ◽  
Stimulation Of

One hundred years ago, D'Arsonval and Beer first described the effects of magnetic fields on human brain function. Placing one's head into a powerful magnet produced phosphenes, vertigo or even syncopes (George & Belmaker, 2000). However, only since 1985 has the technology of fast discharging capacitors developed sufficiently to generate reproducible effects across the intact skull, with peak magnetic field strengths of about 1–2 tesla (Barker et al, 1985). The headline-grabbing news has been about therapeutic applications of transcranial magnetic stimulation (TMS), but in the meantime a revolution in functional brain research has taken place, based on the manipulation of brain activity by focused magnetic fields. TMS applied in this way is, in a manner of speaking, brain imaging in the reverse. While common modes of functional brain imaging, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), demonstrate associations between brain metabolic activity and ‘brain tasks', the causal interpretation of such associations can be difficult. Is the frontal lobe activation observed during a memory task, for example, necessary for performing the task, or does it correspond to monitoring activity that runs parallel to task performance proper? If, on the other hand, focal brain activation during TMS results in a muscle twitch, there is no doubt that stimulation of at least some of the neurons within the magnetic field is sufficient cause for the observed movement. Functional neuroimaging is now often combined with TMS, carried out in the same session in order to exploit the complementary strengths of the methods. Although direct stimulation of association (as opposed to motor or sensory) cortex does not usually result in an observable response, TMS applied in repetitive trains can produce reversible ‘lesions'. By interfering with tasks that are dependent on the functioning of the stimulated neurons, it can thus contribute to the localisation of brain function.

Interaction of histamine with noradrenergic constrictory mechanisms in cat cerebral arteries and veins

1983 ◽  
Vol 61 (7) ◽  
pp. 756-763 ◽  
Author(s):  
Paul M. Gross ◽  
A. Murray Harper ◽  
Graham M. Teasdale
Keyword(s):  
Cerebral Arteries ◽  
Sympathetic Nerves ◽  
Histamine Receptor ◽  
Inhibitory Influence ◽  
Sympathetic Nerve Stimulation ◽  
Pial Arteries ◽  
Simultaneous Application ◽  
Arteries And Veins ◽  
Stimulation Of

We examined responses of pial arteries and veins in situ to noradrenergic stimuli in the presence of histamine. Electrical stimulation of sympathetic nerves and perivascular microapplication of norepinephrine in mock cerebrospinal fluid produced constriction of arteries and veins in anesthetized cats. During simultaneous perivascular injection of histamine, these noradrenergic responses were attenuated or reversed. In both arteries and veins, constriction from sympathetic nerve stimulation was prevented by simultaneous application of the histamine receptor agonists, pyridylethylamine (H1) or impromidine (H2), results that suggest interference involving both types of histamine receptors. In arteries, impromidine, but not pyridylethylamine, inhibited constriction resulting from exogenous norepinephrine. Our findings indicate that histamine may have an inhibitory influence, exerted through both receptor types, on noradrenergic mechanisms in cerebral vessels.

scholarly journals Effect of Aging, Gender and Sensory Stimulation of TRPV1 Receptors with Capsaicin on Spontaneous Swallowing Frequency in Patients with Oropharyngeal Dysphagia: A Proof-of-Concept Study

Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 461
Author(s):  
Weslania Nascimento ◽  
Noemí Tomsen ◽  
Saray Acedo ◽  
Cristina Campos-Alcantara ◽  
Christopher Cabib ◽  
...  
Keyword(s):  
Oropharyngeal Dysphagia ◽  
Sensory Stimulation ◽  
Age And Gender ◽  
Post Stroke ◽  
Brainstem Reflex ◽  
Trpv1 Receptors ◽  
Volume Viscosity ◽  
And Gender ◽  
Effect Of Age ◽  
Stimulation Of

Spontaneous swallowing contributes to airway protection and depends on the activation of brainstem reflex circuits in the central pattern generator (CPG). We studied the effect of age and gender on spontaneous swallowing frequency (SSF) in healthy volunteers and assessed basal SSF and TRPV1 stimulation effect on SSF in patients with post-stroke oropharyngeal dysphagia (OD). The effect of age and gender on SSF was examined on 141 healthy adult volunteers (HV) divided into three groups: GI—18–39 yr, GII—40–59 yr, and GIII—>60 yr. OD was assessed by the Volume–Viscosity Swallowing Test (VVST). The effect of sensory stimulation with capsaicin 10−5 M (TRPV1 agonist) was evaluated in 17 patients with post-stroke OD, using the SSF. SSF was recorded in all participants during 10 min using surface electromyography (sEMG) of the suprahyoid muscles and an omnidirectional accelerometer placed over the cricothyroid cartilage. SSF was significantly reduced in GII (0.73 ± 0.50 swallows/min; p = 0.0385) and GIII (0.50 ± 0.31 swallows/min; p < 0.0001) compared to GI (1.03 ± 0.62 swallows/min), and there was a moderate significant correlation between age and SFF (r = −0.3810; p < 0.0001). No effect of gender on SSF was observed. Capsaicin caused a strong and significant increase in SSF after the TRPV1 stimulation when comparing to basal condition (pre-capsaicin: 0.41 ± 0.32 swallows/min vs post-capsaicin: 0.81 ± 0.51 swallow/min; p = 0.0003). OD in patients with post-stroke OD and acute stimulation with TRPV1 agonists caused a significant increase in SSF, further suggesting the potential role of pharmacological stimulation of sensory pathways as a therapeutic strategy for CPG activation in patients with OD.

Tension response of mammalian muscle to intra-arterial acetylcholine

1960 ◽  
Vol 198 (3) ◽  
pp. 507-510 ◽  
Author(s):  
Peter T. Rowley ◽  
Jay B. Wells ◽  
Richard L. Irwin
Keyword(s):  
Dose Response ◽  
Contractile Response ◽  
Tibialis Anterior Muscle ◽  
Arterial Occlusion ◽  
Isometric Tension ◽  
Neural Stimulation ◽  
Dose Response Relationship ◽  
Mammalian Muscle ◽  
Tension Response ◽  
Stimulation Of

Using isometric tension recording of the tibialis anterior muscle of the cat, the response to intra-arterial acetylcholine injection was studied and compared to the response to electrical stimulation of the nerve. The amount of acetylcholine, the rate of injection and the volume of diluent injected are interrelated factors in the production of tension. Regardless of the amount and concentration of the acetylcholine injected, the contractile response of the muscle has a slower rate of rise and a longer duration than the response from single maximal impulse stimulation to the nerve and a maximal tension less than from a tetanic neural stimulation. The dose-response relationship between the injected acetylcholine and the resultant tension and its modification by curare are described. The steep portion of the dose-response curve was found to occur in most experiments between 0.5 and 6.0 µg. A method of supplying blood to the muscle is described which provides more reliable intermittent arterial occlusion during injection.

Capsaicin-activated bronchial- and alveolar-initiated pathways regulating tracheal ciliary beat frequency

1994 ◽  
Vol 77 (3) ◽  
pp. 1239-1245 ◽  
Author(s):  
M. Eljamal ◽  
L. B. Wong ◽  
D. B. Yeates
Keyword(s):  
Low Dose ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Neural Stimulation ◽  
Short Exposure ◽  
Tracheal Lumen ◽  
Prolonged Stimulation ◽  
Prior Administration ◽  
Stimulation Of ◽  
Ciliary Beat

We questioned whether the prolonged stimulation of ciliary beat frequency (CBF) to a short exposure of low-dose capsaicin (Wong et al. J. Appl. Physiol. 68: 257–2580, 1990) could be due to the activation of indirect pathways involving neural reflexes initiated independently in the bronchi and alveoli. Tracheal CBF (CBFtr) was measured temporally in anesthetized groups of 10 dogs by means of heterodyne-mode correlation analysis laser light scattering. To elucidate the site of the afferent neural stimulation and the efferent mediators affecting the ciliated epithelium, capsaicin (3 nM) aerosol was delivered for 4 min, either predominantly to the bronchi or to the alveolar regions, with use of pulsed aerosol techniques. This resulted in 13 pg of bronchial (85%) and 10 pg of alveolar (96%) capsaicin deposited, which caused marked stimulation of CBFtr with maxima at 7 and 35 min, respectively. Prior administration of aerosolized indomethacin to the bronchi or aerosolized cromolyn to the alveoli inhibited the bronchial and alveolar responses, respectively. Prior administration of aerosolized hexamethonium to the tracheal lumen blocked the stimulatory CBFtr responses from both capsaicin challenges. Ipratropium or propranolol aerosols delivered to the tracheal lumen also inhibited these responses. It is proposed that these pathways comprise one set of sensitive mechanisms to ensure a prolonged stimulation of CBF to effect the removal of secretions and the irritant from the lungs.

scholarly journals Autosomal dominant polycythemia

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1208-1214 ◽  
Author(s):  
JT Prchal ◽  
WM Crist ◽  
E Goldwasser ◽  
G Perrine ◽  
JF Prchal
Keyword(s):  
Autosomal Dominant ◽  
Oxygen Affinity ◽  
Colony Growth ◽  
Blood Oxygen ◽  
Autosomal Dominant Trait ◽  
Volume Measurements ◽  
Blood Oxygen Affinity ◽  
Low Levels ◽  
Stimulation Of

Two families with polycythemia inherited as an autosomal dominant trait are described. Serial hemoglobin determinations in multiple family members and RBC volume measurements in selected affected subjects documented their polycythemia. Measurements of arterial p02s, p50s, and blood oxygen affinity were normal in all affected individuals from each family who were tested. Erythropoietin (EPO) levels were low in affected individuals from family 1 and normal in affected members of family 2. Stimulation of in vitro CFU-E colony growth by low levels of EPO was significantly increased in subjects from family 1, but normal in those affected from family 2. We conclude that although the inheritance pattern for the polycythemia in both of these families appeared to be the same, the biologic defect leading to the disorder in each of these unique families was different. The precise mechanism of the increased EPO sensitivity noted in affected subjects from family 1 awaits elucidation.

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