scholarly journals Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

2004 ◽  
Vol 24 (9) ◽  
pp. 1057-1068 ◽  
Author(s):  
Hrachya Nersesyan ◽  
Peter Herman ◽  
Ersan Erdogan ◽  
Fahmeed Hyder ◽  
Hal Blumenfeld
Keyword(s):  
Visual Cortex ◽  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Barrel Cortex ◽  
Similar Distribution ◽  
Somatosensory Stimulation ◽  
Doppler Flowmetry ◽  
Absence Seizures ◽  
Generalized Seizures ◽  
Whisker Stimulation

There is broad agreement that generalized tonic–clonic seizures (GTCS) and normal somatosensory stimulation are associated with increases in regional CBF. However, the data regarding CBF changes during absence seizures are controversial. Electrophysiologic studies in WAG/Rij rats, an established animal model of absence seizures, have shown spike-wave discharges (SWD) that are largest in the perioral somatosensory cortex while sparing the visual cortex. Recent functional magnetic resonance imaging (fMRI) studies in the same model have also shown localized increases in fMRI signals in the perioral somatosensory cortex during SWD. Because fMRI signals are only indirectly related to neuronal activity, the authors directly measured CBF and neuronal activity from specific microdomains of the WAG/Rij cortex using a specially designed probe combining laser-Doppler flowmetry and extracellular microelectrode recordings under fentanyl/haloperidol anesthesia. Using this approach, parallel increases in neuronal activity and CBF were observed during SWD in the whisker somatosensory (barrel) cortex, whereas the visual cortex showed no significant changes. For comparison, these measurements were repeated during somatosensory (whisker) stimulation, and bicuculline-induced GTCS in the same animals. Interestingly, whisker stimulation increased neuronal activity and CBF in the barrel cortex more than during SWD. During GTCS, much larger increases that included both the somatosensory and visual cortex were observed. Thus, SWD in this model produce parallel localized increases in neuronal activity and CBF with similar distribution to somatosensory stimulation, whereas GTCS produce larger and more widespread changes. The normal response to somatosensory stimulation appears to be poised between two abnormal responses produced by two physiologically different types of seizures.

Angiotensin II attenuates functional hyperemia in the mouse somatosensory cortex

2003 ◽  
Vol 285 (5) ◽  
pp. H1890-H1899 ◽  
Author(s):  
Ken Kazama ◽  
Gang Wang ◽  
Kelly Frys ◽  
Josef Anrather ◽  
Costantino Iadecola
Keyword(s):  
Angiotensin Ii ◽  
Somatosensory Cortex ◽  
Neural Activity ◽  
Brain Regions ◽  
Synaptic Activity ◽  
Nitric Oxide Donor ◽  
Ang Ii ◽  
Functional Hyperemia ◽  
Doppler Flowmetry ◽  
Whisker Stimulation

We investigated whether angiotensin II (ANG II), a peptide that plays a central role in the genesis of hypertension, alters the coupling between synaptic activity and cerebral blood flow (CBF), a critical homeostatic mechanism that assures adequate cerebral perfusion to active brain regions. The somatosensory cortex was activated by stroking the facial whiskers in anesthetized C57BL/6J mice while local CBF was recorded by laser-Doppler flowmetry. Intravenous ANG II infusion (0.25 μg·kg–1·min–1) increased mean arterial pressure (MAP) from 82 ± 2 to 102 ± 3 mmHg ( P < 0.05) without affecting resting CBF ( P > 0.05). ANG II attenuated the CBF increase produced by whisker stimulation by 65% ( P < 0.05) but did not affect the response to hypercapnia or to neocortical application of the nitric oxide donor S-nitroso- N-acetyl penicillamine ( P > 0.05). The effect of ANG II on functional hyperemia persisted if the elevation in MAP was offset by controlled hemorrhage or prevented by topical application of the peptide to the activated cortex. ANG II did not reduce the amplitude of the P1 wave of the field potentials evoked by whisker stimulation ( P > 0.05). Infusion of phenylephrine increased MAP ( P > 0.05 from ANG II) but did not alter the functional hyperemic response ( P > 0.05). The data suggest that ANG II alters the coupling between CBF and neural activity. The mechanisms of the effect are not related to the elevation in MAP and/or to inhibition of the synaptic activity evoked by whisker stimulation. The imbalance between CBF and neural activity induced by ANG II may alter the homeostasis of the neuronal microenvironment and contribute to brain dysfunction during ANG II-induced hypertension.

Involvement of the lemniscal and paralemniscal pathways in the perception of direction and neuronal activity in the barrel cortex in rodent single-whisker stimulation

2009 ◽  
Vol 65 ◽  
pp. S212-S213
Author(s):  
Shinya Nakamura ◽  
Takaaki Narumi ◽  
Shin-ichiro Yoshizato ◽  
Ken-Ichiro Tsutsui ◽  
Toshio Iijima
Keyword(s):  
Neuronal Activity ◽  
Barrel Cortex ◽  
Whisker Stimulation

scholarly journals Layer-specific integration of locomotion and concurrent wall touching in mouse barrel cortex

2018 ◽  
Author(s):  
Asli Ayaz ◽  
Andreas Stäuble ◽  
Aman B Saleem ◽  
Fritjof Helmchen
Keyword(s):  
Virtual Reality ◽  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Calcium Imaging ◽  
Barrel Cortex ◽  
Sustained Activity ◽  
Tactile Stimuli ◽  
Layer 2 ◽  
Self Motion ◽  
Increased Activity

During navigation rodents continually sample the environment with their whiskers. How locomotion modulates neuronal activity in somatosensory cortex and how self-motion is integrated with whisker touch remains unclear. Here, we used calcium imaging in mice running in a tactile virtual reality to investigate modulation of neurons in layer 2/3 (L2/3) and L5 of barrel cortex. About a third of neurons in both layers increased activity during running and concomitant whisking, in the absence of touch. Fewer neurons were modulated by whisking alone (<10%). Whereas L5 neurons responded transiently to wall-touching during running, L2/3 neurons showed sustained activity after touch onset. Consistently, neurons encoding running-with-touch were more abundant in L2/3 compared to L5. Few neurons across layers were also sensitive to abrupt perturbations of tactile flow. We propose that L5 neurons mainly report changes in touch conditions whereas L2/3 neurons continually monitor ongoing tactile stimuli during running.

scholarly journals Analysis of Optical Signals Evoked by Peripheral Nerve Stimulation in Rat Somatosensory Cortex: Dynamic Changes in Hemoglobin Concentration and Oxygenation

1999 ◽  
Vol 19 (3) ◽  
pp. 246-259 ◽  
Author(s):  
Masahito Nemoto ◽  
Yasutomo Nomura ◽  
Chie Sato ◽  
Mamoru Tamura ◽  
Kiyohiro Houkin ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Hemoglobin Concentration ◽  
Optical Signal ◽  
Stimulus Onset ◽  
Dynamic Changes ◽  
Doppler Flowmetry ◽  
Optical Signals ◽  
Reflected Light ◽  
Rat Somatosensory Cortex

The origins of reflected light changes associated with neuronal activity (optical signals) were investigated in rat somatosensory cortex with optical imaging, microspectrophotometry, and laser-Doppler flowmetry, and dynamic changes in local hemoglobin concentration and oxygenation were focused on. Functional activation was carried out by 2-second, 5-Hz electrical stimulation of the hind limb under chloralose anesthesia. These measurements were performed at the contralateral parietal cortex through a thinned skull. Regional cortical blood flow (rCBF) started to rise 1.5 seconds after the stimulus onset, peaked at 3.5 seconds (26.7% ± 9.7% increase over baseline), and returned to near baseline by 10 seconds. Optical signal responses at 577, 586, and 805 nm showed a monophasic increase in absorbance coincident with the increase in rCBF; however, the signal responses at 605 and 760 nm were biphasic (an early increase and late decrease in absorbance) and microanatomically heterogeneous. The spectral changes of absorbance indicated that the concentrations of both total hemoglobin and oxyhemoglobin increased together with rCBF; deoxyhemoglobin, increased slightly but distinctly ( P = 0.016 at 1.0 seconds, P = 0.00038 at 1.5 seconds) just before rCBF increases, then decreased. The authors conclude that activity-related optical signals are greatly associated with a moment-to-moment adjustment of rCBF and metabolism to neuronal activity.

scholarly journals Purinergic glio-endothelial coupling during neuronal activity: role of P2Y1 receptors and eNOS in functional hyperemia in the mouse somatosensory cortex

2015 ◽  
Vol 309 (11) ◽  
pp. H1837-H1845 ◽  
Author(s):  
Peter Toth ◽  
Stefano Tarantini ◽  
Antonio Davila ◽  
M. Noa Valcarcel-Ares ◽  
Zsuzsanna Tucsek ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Critical Role ◽  
Neurovascular Coupling ◽  
No Synthase ◽  
Functional Hyperemia ◽  
Inhibitory Effects ◽  
Pathological Conditions ◽  
Whisker Stimulation

Impairment of moment-to-moment adjustment of cerebral blood flow (CBF) via neurovascular coupling is thought to play a critical role in the genesis of cognitive impairment associated with aging and pathological conditions associated with accelerated cerebromicrovascular aging (e.g., hypertension, obesity). Although previous studies demonstrate that endothelial dysfunction plays a critical role in neurovascular uncoupling in these conditions, the role of endothelial NO mediation in neurovascular coupling responses is not well understood. To establish the link between endothelial function and functional hyperemia, neurovascular coupling responses were studied in mutant mice overexpressing or deficient in endothelial NO synthase (eNOS), and the role of P2Y1 receptors in purinergic glioendothelial coupling was assessed. We found that genetic depletion of eNOS (eNOS−/−) and pharmacological inhibition of NO synthesis significantly decreased the CBF responses in the somatosensory cortex evoked by whisker stimulation and by administration of ATP. Overexpression of eNOS enhanced NO mediation of functional hyperemia. In control mice, the selective and potent P2Y1 receptor antagonist MRS2179 attenuated both whisker stimulation-induced and ATP-mediated CBF responses, whereas, in eNOS−/− mice, the inhibitory effects of MRS2179 were blunted. Collectively, our findings provide additional evidence for purinergic glio-endothelial coupling during neuronal activity, highlighting the role of ATP-mediated activation of eNOS via P2Y1 receptors in functional hyperemia.

Infrared thermal imaging of rat somatosensory cortex with whisker stimulation

2012 ◽  
Vol 112 (7) ◽  
pp. 1215-1222 ◽  
Author(s):  
Takashi Suzuki ◽  
Yasuhiro Ooi ◽  
Junji Seki
Keyword(s):  
Somatosensory Cortex ◽  
Neural Activity ◽  
Thermal Imaging ◽  
Temperature Increase ◽  
Barrel Cortex ◽  
Brain Temperature ◽  
Local Thermal Equilibrium ◽  
Neural Activation ◽  
Whisker Stimulation ◽  
The Brain

The present study aims to validate the applicability of infrared (IR) thermal imaging for the study of brain function through experiments on the rat barrel cortex. Regional changes in neural activity within the brain produce alterations in local thermal equilibrium via increases in metabolic activity and blood flow. We studied the relationship between temperature change and neural activity in anesthetized rats using IR imaging to visualize stimulus-induced changes in the somatosensory cortex of the brain. Sensory stimulation of the vibrissae (whiskers) was given for 10 s using an oscillating whisker vibrator (5-mm deflection at 10, 5, and 1 Hz). The brain temperature in the observational region continued to increase significantly with whisker stimulation. The mean peak recorded temperature changes were 0.048 ± 0.028, 0.054 ± 0.036, and 0.097 ± 0.015°C at 10, 5, and 1 Hz, respectively. We also observed that the temperature increase occurred in a focal spot, radiating to encompass a larger region within the contralateral barrel cortex region during single-whisker stimulation. Whisker stimulation also produced ipsilateral cortex temperature increases, which were localized in the same region as the pial arterioles. Temperature increase in the barrel cortex was also observed in rats treated with a calcium channel blocker (nimodipine), which acts to suppress the hemodynamic response to neural activity. Thus the location and area of temperature increase were found to change in accordance with the region of neural activation. These results indicate that IR thermal imaging is viable as a functional quantitative neuroimaging technique.

Suppression of cortical functional hyperemia to vibrissal stimulation in the rat by epoxygenase inhibitors

2002 ◽  
Vol 283 (5) ◽  
pp. H2029-H2037 ◽  
Author(s):  
Xinqi Peng ◽  
Juan R. Carhuapoma ◽  
Anish Bhardwaj ◽  
Nabil J. Alkayed ◽  
John R. Falck ◽  
...  
Keyword(s):  
Blood Flow ◽  
Barrel Cortex ◽  
Neural Activation ◽  
Doppler Flowmetry ◽  
Blood Flow Response ◽  
Flow Response ◽  
Whisker Stimulation ◽  
Substrate Inhibitor ◽  
Cytochrome P 450 ◽  
Glial Cell Cultures

Application of glutamate to glial cell cultures stimulates the formation and release of epoxyeicosatrienoic acids (EETs) from arachidonic acid by cytochome P-450 epoxygenases. Epoxygenase inhibitors reduce the cerebral vasodilator response to glutamate and N-methyl-d-aspartate. We tested the hypothesis that epoxygenase inhibitors reduce the somatosensory cortical blood flow response to whisker activation. In chloralose-anesthetized rats, percent changes in cortical perfusion over whisker barrel cortex were measured by laser-Doppler flowmetry during whisker stimulation. Two pharmacologically distinct inhibitors were superfused subdurally: 1) N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH), an epoxygenase substrate inhibitor; and 2) miconazole, a reversible cytochrome P-450 inhibitor acting on the heme moiety. Superfusion with 5 μmol/l MS-PPOH decreased the hyperemic response to whisker stimulation by 28% (from 25 ± 9 to 18 ± 7%, means ± SD, n = 8). With 20 μmol/l MS-PPOH superfusion, the response was decreased by 69% (from 28 ± 9% to 9 ± 4%, n = 8). Superfusion with 20 μmol/l miconazole decreased the flow response by 67% (from 31 ± 6% to 10 ± 3%, n = 8). Subsequent superfusion with vehicle restored the response to 26 ± 11%. Indomethacin did not prevent MS-PPOH inhibition of the flow response, suggesting that EET-related vasodilation was not dependent solely on cyclooxygenase metabolism of 5,6-EET. Neither MS-PPOH nor miconazole changed baseline flow, reduced the blood flow response to an adenosine A2 agonist, or decreased somatosensory evoked potentials. The marked reduction of the cortical flow response to whisker stimulation with two different types of epoxygenase inhibitors indicates that EETs play an important role in the physiological coupling of blood flow to neural activation.

Characterization of CBF response to somatosensory stimulation: model and influence of anesthetics

1993 ◽  
Vol 264 (4) ◽  
pp. H1223-H1228 ◽  
Author(s):  
U. Lindauer ◽  
A. Villringer ◽  
U. Dirnagl
Keyword(s):  
Somatosensory Cortex ◽  
Laser Doppler Flowmetry ◽  
Parietal Bone ◽  
Laser Doppler ◽  
High Temporal Resolution ◽  
Somatosensory Stimulation ◽  
Doppler Flowmetry ◽  
Cranial Window ◽  
Mystacial Vibrissae ◽  
Alpha Chloralose

We investigated the cerebral blood flow (CBF) response to somatosensory stimulation. Stimulation of neuronal activity was performed by deflection (2-3/s) of the mystacial vibrissae in rats over a period of 60 s, and regional cortical CBF was measured continuously in the contralateral somatosensory cortex with laser-Doppler flowmetry. CBF within the somatosensory cortex was studied through the parietal bone thinned to translucency (n = 7) or through a closed cranial window with the dura mater removed (n = 7). In addition, the differential effect of anesthetics (halothane-N2O, n = 5; thiobutabarbiturate, n = 5; and alpha-chloralose, n = 7) on the CBF response to stimulation was investigated. After a rapid increase after stimulation onset (maximum reached within 2-3 s), CBF remained above baseline with a slight tendency to decrease despite continued stimulation. On termination of stimulation, CBF fell to near prestimulation values within 2-3 s. The following mean CBF responses above baseline during the 60-s stimulation period were obtained: halothane-N2O anesthesia, 25.4 +/- 5.9%; thiobutabarbiturate anesthesia, 10.6 +/- 2.4%; and alpha-chloralose anesthesia, 16.9 +/- 2.3 (through the translucent bone) and 16.2 +/- 2.9% (closed cranial window, dura removed). We conclude that coupling of CBF to neuronal function has a very high temporal resolution (< 3 s) and that whisker deflection in rats provides a physiological stimulus to study coupling with laser-Doppler flowmetry.

scholarly journals Stimulus-Induced Intercolumnar Synchronization of Neuronal Activity in Rat Barrel Cortex: A Laminar Analysis

2004 ◽  
Vol 92 (3) ◽  
pp. 1464-1478 ◽  
Author(s):  
Mengliang Zhang ◽  
Kevin D. Alloway
Keyword(s):  
Neuronal Activity ◽  
Cross Correlation ◽  
Barrel Cortex ◽  
Sensory Information ◽  
Stimulus Frequency ◽  
Correlation Coefficients ◽  
Brain Regions ◽  
Neuronal Synchronization ◽  
Cross Correlation Analysis ◽  
Whisker Stimulation

We used cross-correlation analysis to characterize the coordination of stimulus-induced neuronal activity in the primary somatosensory barrel cortex of isoflurane-anesthetized rats. On each trial, multiple whiskers were simultaneously deflected at frequencies that corresponded to 2, 5, 8, or 11 Hz. Among 476 neuron pairs that we examined, 342 (71.8%) displayed significant peaks of synchronized activity that exceeded the 99.9% confidence limits. The incidence and strength of these functional associations varied across different cortical layers. Only 52.9% of neuron pairs in layer IV displayed synchronized responses, whereas 84.1% of the infragranular neuron pairs were synchronized during whisker stimulation. Neuronal synchronization was strongest in the infragranular layers, weakest in layer IV, and varied according to the columnar configuration of the neuron pairs. Thus correlation coefficients were largest for neuron pairs in the same whisker barrel row but were smallest for neurons in different rows and arcs. Spontaneous activity in the infragranular layers was also synchronized to a greater degree than in the other layers. Although infragranular neuron pairs displayed similar amounts of synchronization in response to each stimulus frequency, granular and supragranular neurons were synchronized mainly during stimulation at 2 or 5 Hz. These results are consistent with previous studies indicating that infragranular neurons have intrinsic properties that facilitate synchronized activity, and they suggest that neuronal synchronization plays an important role in transmitting sensory information to other cortical or subcortical brain regions.

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