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14 results on '"brain pulsations"'

1. Accelerated multislice MRI with patterned excitation.

Author

de Zwart, Jacco A., van Gelderen, Peter, Wang, Yicun, and Duyn, Jeff H.

Subjects
MAGNETIC resonance imaging, DIFFUSION measurements
Abstract

Purpose: Accelerate multislice 2D MRI by using RF pulses that simultaneously act on different slices to combine contrast preparation and image acquisition. Theory and Methods: MRI applications often require the use of multiple RF pulses to generate desired contrast and prepare the signal for readout. Examples are the use of inversion prepulses to generate T1 contrast, or the use of spin‐echo preparations to generate T2 or diffusion contrast. In multislice MRI, this separation of contrast preparation and readout can render scans time‐inefficient and lengthy. We introduce a class of pulse sequences that overcomes this inefficiency by combining contrast preparation and signal readout. This is accomplished by using RF pulses that manipulate the magnetization of multiple slices simultaneously and a gradient crusher scheme that selects a target slice for readout. Results: Feasibility of the method was demonstrated for spin echo–based measurement of water diffusion and tissue pulsation in human brain at 3 T. Increases in time‐efficiency and reductions in scan time were highly dependent on specific implementation and reached as high as 25% and 53%, respectively. Conclusion: A novel approach to multislice MRI is demonstrated that reduces scan time for specific applications. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Increased interictal synchronicity of respiratory related brain pulsations in epilepsy.

Author

Kananen, Janne, Järvelä, Matti, Korhonen, Vesa, Tuovinen, Timo, Huotari, Niko, Raitamaa, Lauri, Helakari, Heta, Väyrynen, Tommi, Raatikainen, Ville, Nedergaard, Maiken, Ansakorpi, Hanna, Jacobs, Julia, LeVan, Pierre, and Kiviniemi, Vesa

Abstract

Respiratory brain pulsations have recently been shown to drive electrophysiological brain activity in patients with epilepsy. Furthermore, functional neuroimaging indicates that respiratory brain pulsations have increased variability and amplitude in patients with epilepsy compared to healthy individuals. To determine whether the respiratory drive is altered in epilepsy, we compared respiratory brain pulsation synchronicity between healthy controls and patients. Whole brain fast functional magnetic resonance imaging was performed on 40 medicated patients with focal epilepsy, 20 drug-naïve patients and 102 healthy controls. Cerebrospinal fluid associated respiratory pulsations were used to generate individual whole brain respiratory synchronization maps, which were compared between groups. Finally, we analyzed the seizure frequency effect and diagnostic accuracy of the respiratory synchronization defect in epilepsy. Respiratory brain pulsations related to the verified fourth ventricle pulsations were significantly more synchronous in patients in frontal, periventricular and mid-temporal regions, while the seizure frequency correlated positively with synchronicity. The respiratory brain synchronicity had a good diagnostic accuracy (ROCAUC = 0.75) in discriminating controls from medicated patients. The elevated respiratory brain synchronicity in focal epilepsy suggests altered physiological effect of cerebrospinal fluid pulsations possibly linked to regional brain water dynamics involved with interictal brain physiology. [ABSTRACT FROM AUTHOR]

Published
2022
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3. Dynamic brain ADC variations over the cardiac cycle and their relation to tissue strain assessed with DENSE at high‐field MRI.

Author

Sloots, Jacob‐Jan, Froeling, Martijn, Biessels, Geert Jan, and Zwanenburg, Jaco J. M.

Subjects
HEART beat, GRAY matter (Nerve tissue), WHITE matter (Nerve tissue), MAGNETIC resonance imaging, EXTRACELLULAR fluid
Abstract

Purpose: The ADC of brain tissue slightly varies over the cardiac cycle. This variation could reflect physiology, including mixing of the interstitial fluid, relevant for brain waste clearance. However, it is known from cardiac diffusion imaging that tissue deformation by itself affects the magnitude of the MRI signal, leading to artificial ADC variations as well. This study investigates to what extent tissue deformation causes artificial ADC variations in the brain. Theory and Methods: We implemented a high‐field MRI sequence with stimulated echo acquisition mode that simultaneously measures brain tissue deformation and ADC. Based on the measured tissue deformation, we simulated the artificial ADC variation by combining established theoretical frameworks and compared the results with the measured ADC variation. We acquired data in 8 healthy volunteers with diffusion weighting b = 300 and b = 1000 s/mm2. Results: Apparent diffusion coefficient variation was largest in the feet‐to‐head direction and showed the largest deviation from the mean ADC at peak systole. Artificial ADC variation estimated from tissue deformation was 1.3 ± 0.37·10−5 mm2/s in the feet‐to‐head direction for gray matter, and 0.75 ± 0.29·10−5 mm2/s for white matter. The measured ADC variation in the feet‐to‐head direction was 5.6·10−5 ± 1.5·10−5 mm2/s for gray matter and 3.2·10−5 ± 1.0·10−5 mm2/s for white matter, which was a factor of 3.5 ± 0.82 and 3.4 ± 0.57 larger than the artificial diffusion variations. The measured diffusion variations in the right‐to‐left/anterior‐to‐posterior direction were a factor of 1.5 ± 1.0/1.7 ± 1.4 and 2.0 ± 0.91/2.5 ± 0.94 larger than the artificial diffusion variations for gray matter and white matter, respectively. Conclusion: Apparent diffusion coefficient variations in the brain likely largely reflect physiology. [ABSTRACT FROM AUTHOR]

Published
2022
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4. Human NREM Sleep Promotes Brain-Wide Vasomotor and Respiratory Pulsations.

Author

Helakari, Heta, Korhonen, Vesa, Holst, Sebastian C., Piispala, Johanna, Kallio, Mika, Väyrynen, Tommi, Huotari, Niko, Raitamaa, Lauri, Tuunanen, Johanna, Kananen, Janne, Järvelä, Matti, Tuovinen, Timo, Raatikainen, Ville, Borchardt, Viola, Kinnunen, Hannu, Nedergaard, Maiken, and Kiviniemi, Vesa

Subjects
*DISTRIBUTION (Probability theory), *SLEEP, *CEREBROSPINAL fluid, *MAGNETIC resonance, *EYE movements
Abstract

The physiological underpinnings of the necessity of sleep remain uncertain. Recent evidence suggests that sleep increases the convection of cerebrospinal fluid (CSF) and promotes the export of interstitial solutes, thus providing a framework to explain why all vertebrate species require sleep. Cardiovascular, respiratory and vasomotor brain pulsations have each been shown to drive CSF flow along perivascular spaces, yet it is unknown how such pulsations may change during sleep in humans. To investigate these pulsation phenomena in relation to sleep, we simultaneously recorded fast fMRI, magnetic resonance encephalography (MREG), and electroencephalography (EEG) signals in a group of healthy volunteers. We quantified sleep-related changes in the signal frequency distributions by spectral entropy analysis and calculated the strength of the physiological (vasomotor, respiratory, and cardiac) brain pulsations by power sum analysis in 15 subjects (age 26.5 6 4.2 years, 6 females). Finally, we identified spatial similarities between EEG slow oscillation (0.2-2 Hz) power and MREG pulsations. Compared with wakefulness, nonrapid eye movement (NREM) sleep was characterized by reduced spectral entropy and increased brain pulsation intensity. These effects were most pronounced in posterior brain areas for very low-frequency (£ 0.1 Hz) vasomotor pulsations but were also evident brain-wide for respiratory pulsations, and to a lesser extent for cardiac brain pulsations. There was increased EEG slow oscillation power in brain regions spatially overlapping with those showing sleep-related MREG pulsation changes. We suggest that reduced spectral entropy and enhanced pulsation intensity are characteristic of NREM sleep. With our findings of increased power of slow oscillation, the present results support the proposition that sleep promotes fluid transport in human brain. [ABSTRACT FROM AUTHOR]

Published
2022
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5. Human NREM Sleep Promotes Brain-Wide Vasomotor and Respiratory Pulsations

Author

Helakari, H. (Heta), Korhonen, V. (Vesa), Holst, S. C. (Sebastian C.), Piispala, J. (Johanna), Kallio, M. (Mika), Väyrynen, T. (Tommi), Huotari, N. (Niko), Raitamaa, L. (Lauri), Tuunanen, J. (Johanna), Kananen, J. (Janne), Järvelä, M. (Matti), Tuovinen, T. (Timo), Raatikainen, V. (Ville), Borchardt, V. (Viola), Kinnunen, H. (Hannu), Nedergaard, M. (Maiken), Kiviniemi, V. (Vesa), Helakari, H. (Heta), Korhonen, V. (Vesa), Holst, S. C. (Sebastian C.), Piispala, J. (Johanna), Kallio, M. (Mika), Väyrynen, T. (Tommi), Huotari, N. (Niko), Raitamaa, L. (Lauri), Tuunanen, J. (Johanna), Kananen, J. (Janne), Järvelä, M. (Matti), Tuovinen, T. (Timo), Raatikainen, V. (Ville), Borchardt, V. (Viola), Kinnunen, H. (Hannu), Nedergaard, M. (Maiken), and Kiviniemi, V. (Vesa)

Abstract

The physiological underpinnings of the necessity of sleep remain uncertain. Recent evidence suggests that sleep increases the convection of cerebrospinal fluid (CSF) and promotes the export of interstitial solutes, thus providing a framework to explain why all vertebrate species require sleep. Cardiovascular, respiratory and vasomotor brain pulsations have each been shown to drive CSF flow along perivascular spaces, yet it is unknown how such pulsations may change during sleep in humans. To investigate these pulsation phenomena in relation to sleep, we simultaneously recorded fast fMRI, magnetic resonance encephalography (MREG), and electroencephalography (EEG) signals in a group of healthy volunteers. We quantified sleep-related changes in the signal frequency distributions by spectral entropy analysis and calculated the strength of the physiological (vasomotor, respiratory, and cardiac) brain pulsations by power sum analysis in 15 subjects (age 26.5 ± 4.2 years, 6 females). Finally, we identified spatial similarities between EEG slow oscillation (0.2–2 Hz) power and MREG pulsations. Compared with wakefulness, nonrapid eye movement (NREM) sleep was characterized by reduced spectral entropy and increased brain pulsation intensity. These effects were most pronounced in posterior brain areas for very low-frequency (≤0.1 Hz) vasomotor pulsations but were also evident brain-wide for respiratory pulsations, and to a lesser extent for cardiac brain pulsations. There was increased EEG slow oscillation power in brain regions spatially overlapping with those showing sleep-related MREG pulsation changes. We suggest that reduced spectral entropy and enhanced pulsation intensity are characteristic of NREM sleep. With our findings of increased power of slow oscillation, the present results support the proposition that sleep promotes fluid transport in human brain.

Published
2022

6. Increased interictal synchronicity of respiratory related brain pulsations in epilepsy

Author

Kananen, J. (Janne), Järvelä, M. (Matti), Korhonen, V. (Vesa), Tuovinen, T. (Timo), Huotari, N. (Niko), Raitamaa, L. (Lauri), Helakari, H. (Heta), Väyrynen, T. (Tommi), Raatikainen, V. (Ville), Nedergaard, M. (Maiken), Ansakorpi, H. (Hanna), Jacobs, J. (Julia), LeVan, P. (Pierre), Kiviniemi, V. (Vesa), Kananen, J. (Janne), Järvelä, M. (Matti), Korhonen, V. (Vesa), Tuovinen, T. (Timo), Huotari, N. (Niko), Raitamaa, L. (Lauri), Helakari, H. (Heta), Väyrynen, T. (Tommi), Raatikainen, V. (Ville), Nedergaard, M. (Maiken), Ansakorpi, H. (Hanna), Jacobs, J. (Julia), LeVan, P. (Pierre), and Kiviniemi, V. (Vesa)

Abstract

Respiratory brain pulsations have recently been shown to drive electrophysiological brain activity in patients with epilepsy. Furthermore, functional neuroimaging indicates that respiratory brain pulsations have increased variability and amplitude in patients with epilepsy compared to healthy individuals. To determine whether the respiratory drive is altered in epilepsy, we compared respiratory brain pulsation synchronicity between healthy controls and patients. Whole brain fast functional magnetic resonance imaging was performed on 40 medicated patients with focal epilepsy, 20 drug-naïve patients and 102 healthy controls. Cerebrospinal fluid associated respiratory pulsations were used to generate individual whole brain respiratory synchronization maps, which were compared between groups. Finally, we analyzed the seizure frequency effect and diagnostic accuracy of the respiratory synchronization defect in epilepsy. Respiratory brain pulsations related to the verified fourth ventricle pulsations were significantly more synchronous in patients in frontal, periventricular and mid-temporal regions, while the seizure frequency correlated positively with synchronicity. The respiratory brain synchronicity had a good diagnostic accuracy (ROCAUC = 0.75) in discriminating controls from medicated patients. The elevated respiratory brain synchronicity in focal epilepsy suggests altered physiological effect of cerebrospinal fluid pulsations possibly linked to regional brain water dynamics involved with interictal brain physiology.

Published
2022

7. Increased effect of physiological respiratory brain pulsations in focal-onset epilepsy

Author

Kananen, J. (Janne), Kiviniemi, V. (Vesa), and Ansakorpi, H. (Hanna)

Subjects
glymfaattinen järjestelmä, toiminnallinen MK, glymphatic system, MREG, fMRI, epilepsy, aivopulsaatiot, epilepsia, brain pulsations
Abstract

Neurological brain diseases induce increasing costs in health care around the world. Epilepsies are one of the most common neurological diseases globally. While seizure-freedom is achieved in a majority of patients with proper treatment, epilepsy can still be refractory to antiepileptic medication and can cause impaired quality of life and premature death compared to the general population. In clinical diagnostic work-up, the unpredictable and temporary nature of epileptic activity in the brain with several different specified and still unknown etiologies can make the precise localization of the epileptic foci difficult. A new pathophysiological theory behind epilepsies focuses on neuron-glia interactions and an impeccably functioning blood–brain barrier supporting the homeostasis for unhindered brain functionality. Cerebrospinal fluid is driven by brain pulsations via Aquaporin-4 in the brain and plays a critical role in supporting the water channels balance. Recently developed fast functional neuroimaging methods can be used to study whether this homeostasis is disturbed in patients with focal-onset epilepsy. Additionally, the fast functional MRI sequence, ultra-fast magnetic resonance encephalography (MREG), offers a method for differentiating distinct frequency brain pulsations. Previous evidence with intracranial electroencephalography has shown that respiration directly affects epileptic activity and brain function altogether. Thus, respiratory brain pulsations measured by MREG were a focus of particular interest in comparisons between patients with focal-onset epilepsy and healthy controls in this study, totaling 40and 102 subjects, respectively, gathered during 2012–2020 in Oulu, Finland and Freiburg, Germany. Additionally, we introduce data from 22 patients with new-onset seizure gathered in Oulu, Finland, allowing the exclusion of the potential effect of antiepileptic medication as a cause of the observed changes in observable brain pulsations. In conclusion, the methodology used in this study showed increased intrinsic respiratory brain pulsations in focal-onset epilepsy, offering a novel hypothesis of mechanisms behind the disease. Additionally, these pulsations were increased only at an individual level in epilepsy patients. Naturally, future comparative studies with current imaging studies and modalities will clarify the role and value of MREG in localizing the epileptogenic zone. These results could be explained by the transition in brain glymphatic water convection, which reciprocally affects potassium channels and, thus, brain electrophysiological homeostasis. This finding might at least partly explain the incomplete response to treatment in intractable epilepsy since a remedy to solute the clearance does not yet exist. Tiivistelmä Neurologiset aivosairaudet aiheuttavat alati kasvavia kustannuksia terveydenhuollolle eri puolilla maailmaa. Epilepsiat ovat yksi yleisimmistä neurologisista sairauksista maailmanlaajuisesti. Vaikka suurimmalla osalla potilaista saavutetaan kohtauksettomuus, epilepsia voi kuitenkin olla vaikea, jolloin asianmukaisesta lääkehoidostahuolimatta potilaalle aiheutuu merkittävää elämänlaadun alentumista ja kohonnut riskiennenaikaiselle kuolemalle verrattuna muuhun väestöön. Kliinisessä diagnostiikassa aivojen epileptisen toiminnan ennalta-arvaamattomuus ja kohtauksellisuus useiden tunnettujen ja tuntemattomien syiden vuoksi voi aiheuttaa haasteita epileptisen toiminnanpaikallistamiseen aivokudoksessa. Uusi patofysiologinen teoria epilepsian taustalla keskittyy hermosolujen ja sen tukikudoksen, eli neuronien ja glian vuorovaikutukseen ja veriaivoesteen toimintaan aivojen homeostaasin säilyttämiseksi. Aivo-selkäydinnesteen liikettä ajavat aivoissa tapahtuvat pulsaatiot, jotka Akvaporiini-4 kanavien välityksellä ylläpitävät aivojenvesikanavien tasapainoa. Uudella toiminnallisella neurokuvantamismenetelmällä voidaan tutkia, ovatko homeostaasia ylläpitävät aivojen pulsaatiot häiriintyneet paikallis-alkuisessa epilepsiassa. Lisäksi käytetty ultranopea magneettiresonanssienkefalogrammi (MREG), tarjoaa tutkimusmenetelmän eri taajuuksilla tapahtuvien aivopulsaatioidenerottamiseksi toisistaan. Aikaisemmin on osoitettu kallonsisäisillä aivosähkökäyrämittauksilla, että hengityksellä on suora vaikutus epileptiseen aivotoimintaan ja sen aktiivisuuteen. Tämän vuoksi MREG:lla mitatut aivojen hengityspulsaatiot olivat tutkimuksessa erityisenkiinnostuksen kohteena vertailtaessa paikallis-alkuista epilepsiaa sairastavia potilaita ja terveitä kontrolleja, joita kerättiin vuosien 2012–2020 aikana vastaavasti yhteensä 40 ja 102 kappaletta Oulussa ja Freiburgissa Saksassa. Lisäksi esittelemme Oulussa kerätyn 22 tuoreen kohtauspotilaan aineiston, joka mahdollisti lääkityksen vaikutuksenpoissulkemisen aivojen pulsaatioihin. Yhteenvetona voidaan todeta, että käytetty menetelmä osoitti aivojen hengityspulsaatioiden muuttuneen paikallisalkuisessa epilepsiassa tarjoten uuden hypoteettisenmekanismin epilepsian syynä. Lisäksi havaitsimme pulsaatioiden muuttumisen paikallisesti yksilöllisellä tasolla. Luonnollisesti tulevaisuudessa tarvitaan lisää komparatiivisia tutkimuksia eri modaliteettien välillä vertailemaan MREG:n hyödyllisyyttä epileptogeenisen alueen paikantamisessa. Saadut tulokset voidaan selittää aivojen muuttuneella glymfaattisen veden puhdistumalla, joka vaikuttaa aivokudoksessa vastavuoroisestikaliumkanaviin ja siten elektrofysiologiseen tasapainoon. Tämä voisi mahdollisesti selittää osittaista hoitovastetta vaikeassa epilepsiassa, koska glymfaattiseen puhdistumaan vaikuttavia hoitoja ei toistaiseksi ole käytössä.

Published
2021

8. Increased effect of physiological respiratory brain pulsations in focal-onset epilepsy

Author

Kiviniemi, V. (Vesa), Ansakorpi, H. (Hanna), Kananen, J. (Janne), Kiviniemi, V. (Vesa), Ansakorpi, H. (Hanna), and Kananen, J. (Janne)

Abstract

Neurological brain diseases induce increasing costs in health care around the world. Epilepsies are one of the most common neurological diseases globally. While seizure-freedom is achieved in a majority of patients with proper treatment, epilepsy can still be refractory to antiepileptic medication and can cause impaired quality of life and premature death compared to the general population. In clinical diagnostic work-up, the unpredictable and temporary nature of epileptic activity in the brain with several different specified and still unknown etiologies can make the precise localization of the epileptic foci difficult. A new pathophysiological theory behind epilepsies focuses on neuron-glia interactions and an impeccably functioning blood–brain barrier supporting the homeostasis for unhindered brain functionality. Cerebrospinal fluid is driven by brain pulsations via Aquaporin-4 in the brain and plays a critical role in supporting the water channels balance. Recently developed fast functional neuroimaging methods can be used to study whether this homeostasis is disturbed in patients with focal-onset epilepsy. Additionally, the fast functional MRI sequence, ultra-fast magnetic resonance encephalography (MREG), offers a method for differentiating distinct frequency brain pulsations. Previous evidence with intracranial electroencephalography has shown that respiration directly affects epileptic activity and brain function altogether. Thus, respiratory brain pulsations measured by MREG were a focus of particular interest in comparisons between patients with focal-onset epilepsy and healthy controls in this study, totaling 40and 102 subjects, respectively, gathered during 2012–2020 in Oulu, Finland and Freiburg, Germany. Additionally, we introduce data from 22 patients with new-onset seizure gathered in Oulu, Finland, allowing the exclusion of the potential effect of antiepileptic medication as a cause of the observed changes in observable brain pulsations. In, Tiivistelmä Neurologiset aivosairaudet aiheuttavat alati kasvavia kustannuksia terveydenhuollolle eri puolilla maailmaa. Epilepsiat ovat yksi yleisimmistä neurologisista sairauksista maailmanlaajuisesti. Vaikka suurimmalla osalla potilaista saavutetaan kohtauksettomuus, epilepsia voi kuitenkin olla vaikea, jolloin asianmukaisesta lääkehoidostahuolimatta potilaalle aiheutuu merkittävää elämänlaadun alentumista ja kohonnut riskiennenaikaiselle kuolemalle verrattuna muuhun väestöön. Kliinisessä diagnostiikassa aivojen epileptisen toiminnan ennalta-arvaamattomuus ja kohtauksellisuus useiden tunnettujen ja tuntemattomien syiden vuoksi voi aiheuttaa haasteita epileptisen toiminnanpaikallistamiseen aivokudoksessa. Uusi patofysiologinen teoria epilepsian taustalla keskittyy hermosolujen ja sen tukikudoksen, eli neuronien ja glian vuorovaikutukseen ja veriaivoesteen toimintaan aivojen homeostaasin säilyttämiseksi. Aivo-selkäydinnesteen liikettä ajavat aivoissa tapahtuvat pulsaatiot, jotka Akvaporiini-4 kanavien välityksellä ylläpitävät aivojenvesikanavien tasapainoa. Uudella toiminnallisella neurokuvantamismenetelmällä voidaan tutkia, ovatko homeostaasia ylläpitävät aivojen pulsaatiot häiriintyneet paikallis-alkuisessa epilepsiassa. Lisäksi käytetty ultranopea magneettiresonanssienkefalogrammi (MREG), tarjoaa tutkimusmenetelmän eri taajuuksilla tapahtuvien aivopulsaatioidenerottamiseksi toisistaan. Aikaisemmin on osoitettu kallonsisäisillä aivosähkökäyrämittauksilla, että hengityksellä on suora vaikutus epileptiseen aivotoimintaan ja sen aktiivisuuteen. Tämän vuoksi MREG:lla mitatut aivojen hengityspulsaatiot olivat tutkimuksessa erityisenkiinnostuksen kohteena vertailtaessa paikallis-alkuista epilepsiaa sairastavia potilaita ja terveitä kontrolleja, joita kerättiin vuosien 2012–2020 aikana vastaavasti yhteensä 40 ja 102 kappaletta Oulussa ja Freiburgissa Saksassa. Lisäksi esittelemme Oulussa kerätyn 22 tuoreen kohtauspotilaan aineiston, joka mahdollisti lääkityksen vaikutuk

Published
2021

9. Respiratory-related brain pulsations are increased in epilepsy:a two-centre functional MRI study

Author

Kananen, J. (Janne), Helakari, H. (Heta), Korhonen, V. (Vesa), Huotari, N. (Niko), Järvela, M. (Matti), Raitamaa, L. (Lauri), Raatikainen, V. (Ville), Rajna, Z. (Zalan), Tuovinen, T. (Timo), Nedergaard, M. (Maiken), Jacobs, J. (Julia), LeVan, P. (Pierre), Ansakorpi, H. (Hanna), Kiviniemi, V. (Vesa), Kananen, J. (Janne), Helakari, H. (Heta), Korhonen, V. (Vesa), Huotari, N. (Niko), Järvela, M. (Matti), Raitamaa, L. (Lauri), Raatikainen, V. (Ville), Rajna, Z. (Zalan), Tuovinen, T. (Timo), Nedergaard, M. (Maiken), Jacobs, J. (Julia), LeVan, P. (Pierre), Ansakorpi, H. (Hanna), and Kiviniemi, V. (Vesa)

Abstract

Resting-state functional MRI has shown potential for detecting changes in cerebral blood oxygen level-dependent signal in patients with epilepsy, even in the absence of epileptiform activity. Furthermore, it has been suggested that coefficient of variation mapping of fast functional MRI signal may provide a powerful tool for the identification of intrinsic brain pulsations in neurological diseases such as dementia, stroke and epilepsy. In this study, we used fast functional MRI sequence (magnetic resonance encephalography) to acquire ten whole-brain images per second. We used the functional MRI data to compare physiological brain pulsations between healthy controls (n = 102) and patients with epilepsy (n = 33) and furthermore to drug-naive seizure patients (n = 9). Analyses were performed by calculating coefficient of variation and spectral power in full band and filtered sub-bands. Brain pulsations in the respiratory-related frequency sub-band (0.11–0.51 Hz) were significantly (P < 0.05) increased in patients with epilepsy, with an increase in both signal variance and power. At the individual level, over 80% of medicated and drug-naive seizure patients exhibited areas of abnormal brain signal power that correlated well with the known clinical diagnosis, while none of the controls showed signs of abnormality with the same threshold. The differences were most apparent in the basal brain structures, respiratory centres of brain stem, midbrain and temporal lobes. Notably, full-band, very low frequency (0.01–0.1 Hz) and cardiovascular (0.8–1.76 Hz) brain pulses showed no differences between groups. This study extends and confirms our previous results of abnormal fast functional MRI signal variance in epilepsy patients. Only respiratory-related brain pulsations were clearly increased with no changes in either physiological cardiorespiratory rates or head motion between the subjects. The regional alterations in brain pulsations suggest that mechanisms driving

Published
2020

10. Respiratory-related brain pulsations are increased in epilepsy-a two-centre functional MRI study

Author

Kananen, Janne, Helakari, Heta, Korhonen, Vesa, Huotari, Niko, Jarvela, Matti, Raitamaa, Lauri, Raatikainen, Ville, Rajna, Zalan, Tuovinen, Timo, Nedergaard, Maiken, Jacobs, Julia, LeVan, Pierre, Ansakorpi, Hanna, Kiviniemi, Vesa, Kananen, Janne, Helakari, Heta, Korhonen, Vesa, Huotari, Niko, Jarvela, Matti, Raitamaa, Lauri, Raatikainen, Ville, Rajna, Zalan, Tuovinen, Timo, Nedergaard, Maiken, Jacobs, Julia, LeVan, Pierre, Ansakorpi, Hanna, and Kiviniemi, Vesa

Abstract

Resting-state functional MRI has shown potential for detecting changes in cerebral blood oxygen level-dependent signal in patients with epilepsy, even in the absence of epileptiform activity. Furthermore, it has been suggested that coefficient of variation mapping of fast functional MRI signal may provide a powerful tool for the identification of intrinsic brain pulsations in neurological diseases such as dementia, stroke and epilepsy. In this study, we used fast functional MRI sequence (magnetic resonance encephalography) to acquire ten whole-brain images per second. We used the functional MRI data to compare physiological brain pulsations between healthy controls (n- 102) and patients with epilepsy (n =33) and furthermore to drug-naive seizure patients (n= 9). Analyses were performed by calculating coefficient of variation and spectral power in full band and filtered sub-bands. Brain pulsations in the respiratory-related frequency sub-band (0.11-0.51 Hz) were significantly (P<0.05) increased in patients with epilepsy, with an increase in both signal variance and power. At the individual level, over 80% of medicated and drug-naive seizure patients exhibited areas of abnormal brain signal power that correlated well with the known clinical diagnosis, while none of the controls showed signs of abnormality with the same threshold. The differences were most apparent in the basal brain structures, respiratory centres of brain stem, midbrain and temporal lobes. Notably, full-band, very low frequency (0.01-0.1 Hz) and cardiovascular (0.81.76 Hz) brain pulses showed no differences between groups. This study extends and confirms our previous results of abnormal fast functional MRI signal variance in epilepsy patients. Only respiratory-related brain pulsations were clearly increased with no changes in either physiological cardiorespiratory rates or head motion between the subjects. The regional alterations in brain pulsations suggest that mechanisms driving the cerebros

Published
2020

11. New Systematizations of Nerve Function in the Enlightenment.

Author

Ochs, Sidney

Abstract

With the overturn of the old physiology underpinning Galenic medicine, new physiological foundations for medicine were searched for. Systems based on new physical principles proposed by Galileo and other physicists, and those on chemistry following its transformation from alchemy, were advanced: on physical principles by the iatrophysicists and on chemical principles by the iatrochemists. Both groups proposed agents to replace the ancient concept of animal spirits, but they essentially represented only a change of name. Alongside the nervous system by which sensations were perceived and motor nerves innervating muscles expressed the will, an involuntary nervous system was recognized – one by which the various bodily organs and its movements were carried out independently of the will (autonomously). Since Galen, the intercostal nerve chains were known, but were thought to be an offshoot of the vagus nerve originating from the brain, and it was so figured by Vesalius. These chains were then recognized as not connected directly to the brain, having its origin in neural connectives from the spinal cord. How the ganglia associated with this system, the intercostal chains and the ganglia found elsewhere with the involuntary nerves in the abdomen, their relation to the voluntary nervous system, and mode of action, became a matter of inquiry. BOERHAAVE'S SYSTEM OF NERVE FIBERS One of the most eminent clinicians of his day who incorporated the developments in physics and chemistry into a new system of physiology and medicine was Hermann Boerhaave (1668–1738), whose influential six-volume compendium, Institutiones medicae, was aimed at eliminating metaphysics from medicine and medical science. [ABSTRACT FROM AUTHOR]

Published
2004
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12. Respiratory-related brain pulsations are increased in epilepsy—a two-centre functional MRI study

Author

Ville Raatikainen, Vesa Kiviniemi, Heta Helakari, Pierre LeVan, Julia Jacobs, Hanna Ansakorpi, Zalan Rajna, Janne Kananen, Lauri Raitamaa, Niko Huotari, Vesa Korhonen, Timo Tuovinen, and Matti Järvelä

Subjects
medicine.medical_specialty, Midbrain, 03 medical and health sciences, Epilepsy, 0302 clinical medicine, Cerebrospinal fluid, CONNECTIVITY, Internal medicine, medicine, Respiratory system, Stroke, 030304 developmental biology, brain pulsations, EEG ACTIVATION, 0303 health sciences, INDEPENDENT COMPONENT ANALYSIS, HYPERVENTILATION, medicine.diagnostic_test, fast fMRI, business.industry, AcademicSubjects/SCI01870, General Engineering, Magnetic resonance imaging, FLUCTUATIONS, BARRIER, medicine.disease, NETWORKS, PET, FMRI, Cardiology, epilepsy, Original Article, AcademicSubjects/MED00310, brain physiology, Abnormality, Functional magnetic resonance imaging, business, SLEEP-DEPRIVATION, 030217 neurology & neurosurgery, respiration
Abstract

Resting-state functional MRI has shown potential for detecting changes in cerebral blood oxygen level-dependent signal in patients with epilepsy, even in the absence of epileptiform activity. Furthermore, it has been suggested that coefficient of variation mapping of fast functional MRI signal may provide a powerful tool for the identification of intrinsic brain pulsations in neurological diseases such as dementia, stroke and epilepsy. In this study, we used fast functional MRI sequence (magnetic resonance encephalography) to acquire ten whole-brain images per second. We used the functional MRI data to compare physiological brain pulsations between healthy controls (n = 102) and patients with epilepsy (n = 33) and furthermore to drug-naive seizure patients (n = 9). Analyses were performed by calculating coefficient of variation and spectral power in full band and filtered sub-bands. Brain pulsations in the respiratory-related frequency sub-band (0.11–0.51 Hz) were significantly (P, The study reports markedly elevated focal respiratory-related brain pulsation in epilepsy. The novel technique based on fast functional MRI enables non-invasive evaluation of both individual- and group-level changes. Presented findings suggest a link between epilepsy and glymphatic pulsation abnormality., Graphical Abstract Graphical Abstract

Published
2020

13. The Physics of Hydrocephalus.

Author

Penn, Richard D. and Linninger, Andreas

Subjects
*HYDROCEPHALUS, *FLUID dynamics, *TISSUES, *LIPIDS, *SURGERY
Abstract

This article reviews our previous work on the dynamics of the intracranial cavity and presents new clinically relevant results about hydrocephalus that can be gained from this approach. Simulations based on fluid dynamics and poroelasticity theory are used to predict CSF flow, pressures and brain tissue movement in normal subjects. Communicating hydrocephalus is created in the model by decreasing CSF absorption. The predictions are shown to reflect dynamics demonstrated by structural MRI and cine-MRI studies of normal subjects and hydrocephalus patients. The simulations are then used to explain unilateral hydrocephalus and how hydrocephalus could occur without CSF pulsations. The simulations also predict the known pressure/volume relationships seen on bolus infusions of CSF, and the small transmural pressure gradients observed in animal experiments and in patients with hydrocephalus. The complications and poor performance of shunts based on pressure-sensitive valves are explained and a system of feedback control is suggested as a solution. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Published
2009
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14. Respiratory-related brain pulsations are increased in epilepsy-a two-centre functional MRI study.

Author

Kananen J, Helakari H, Korhonen V, Huotari N, Järvelä M, Raitamaa L, Raatikainen V, Rajna Z, Tuovinen T, Nedergaard M, Jacobs J, LeVan P, Ansakorpi H, and Kiviniemi V

Abstract

Resting-state functional MRI has shown potential for detecting changes in cerebral blood oxygen level-dependent signal in patients with epilepsy, even in the absence of epileptiform activity. Furthermore, it has been suggested that coefficient of variation mapping of fast functional MRI signal may provide a powerful tool for the identification of intrinsic brain pulsations in neurological diseases such as dementia, stroke and epilepsy. In this study, we used fast functional MRI sequence (magnetic resonance encephalography) to acquire ten whole-brain images per second. We used the functional MRI data to compare physiological brain pulsations between healthy controls ( n  = 102) and patients with epilepsy ( n  = 33) and furthermore to drug-naive seizure patients ( n  = 9). Analyses were performed by calculating coefficient of variation and spectral power in full band and filtered sub-bands. Brain pulsations in the respiratory-related frequency sub-band (0.11-0.51 Hz) were significantly ( P  <   0.05) increased in patients with epilepsy, with an increase in both signal variance and power. At the individual level, over 80% of medicated and drug-naive seizure patients exhibited areas of abnormal brain signal power that correlated well with the known clinical diagnosis, while none of the controls showed signs of abnormality with the same threshold. The differences were most apparent in the basal brain structures, respiratory centres of brain stem, midbrain and temporal lobes. Notably, full-band, very low frequency (0.01-0.1 Hz) and cardiovascular (0.8-1.76 Hz) brain pulses showed no differences between groups. This study extends and confirms our previous results of abnormal fast functional MRI signal variance in epilepsy patients. Only respiratory-related brain pulsations were clearly increased with no changes in either physiological cardiorespiratory rates or head motion between the subjects. The regional alterations in brain pulsations suggest that mechanisms driving the cerebrospinal fluid homeostasis may be altered in epilepsy. Magnetic resonance encephalography has both increased sensitivity and high specificity for detecting the increased brain pulsations, particularly in times when other tools for locating epileptogenic areas remain inconclusive., (© The Author(s) (2020). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Published
2020
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