Author

Heta Helakari

Oulu University HospitalORCID 0000-0002-4354-4687Unclaimed ORCID profile · follow to get notified of new preprints

Biology Disciplines

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Organism:human· 8 Approach:statistical model· 8 Assay:imaging· 6 Research Focus:benchmarking· 2 Research Focus:cell-cell communication· 2 Assay:electronic health records· 2 Research Focus:spatial domain detection· 2 Research Focus:cell type annotation· 1

Frequent Co-Authors

Niko HuotariiD· 8 shared Vesa J. KiviniemiiD· 8 shared Vesa O. KorhoneniD· 8 shared Johanna PiispalaiD· 7 shared Johanna TuunaneniD· 7 shared Lauri RaitamaaiD· 7 shared Matti JärveläiD· 7 shared Mika KallioiD· 7 shared

Activity by Year

2020-2026 · peak 3/yr

Co-Author Collaboration Network

10 top collaborators · 45 mutual co-author links

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8 shared papersNeuroscience

Niko HuotariORCID

Mutual co-authors in cluster

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8 papers

Recent·Most cited

Infra-slow (<0.1 Hz) modulation of human brain pulsations in awake and sleep states

Tommi Väyrynen, Heta Helakari, Vesa O. Korhonen, Johanna Tuunanen, Niko Huotari, Janne Kananen, Seyed-Mohsen Ebrahimi, Ahmed Elabasy, Matti Järvelä, Katariina Hautamäki, Katariina Laurén, Lauri Raitamaa, Ulla Salmi, Johanna Piispala, Mika Kallio, Vesa J. Kiviniemi

This study investigates cross-frequency oscillatory interactions in brain pulsations during awake and NREM-sleep states, revealing directional coordination mechanisms between infra-slow, respiratory, and cardiovascular oscillations.

Journal of Neuroscience · Jun 5, 2026Peer-reviewedNeuroscience

Reduced harmonic complexity of brain parenchymal cardiovascular pulse waveforms in Alzheimer's disease

Anssi Koivula, Vilma Perkiömäki, Mika Aho, Aleksi Rasila, Valter Poltojainen, Vesa O. Korhonen, Matti Järvelä, Niko Huotari, Heta Helakari, Johanna Tuunanen, Lauri Raitamaa, Tommi Väyrynen, Johanna Krüger, Vesa J. Kiviniemi, Janne Kananen

This study introduces MREGRHP, a frequency domain imaging method, and finds reduced harmonic complexity in brain pulse waveforms in Alzheimer's disease patients.

NeuroImage · Oct 1, 2025Peer-reviewedNeuroscience

Arousal State Control of Physiological Human Brain Pulsations

Matti Järvelä, Janne Kananen, Heta Helakari, Vesa O. Korhonen, Niko Huotari, Lauri Raitamaa, Johanna Tuunanen, Mika Kallio, Johanna Piispala, Hanna Ansakorpi, Vesa J. Kiviniemi

This study uses fast fMRI to compare brain pulsation patterns in healthy awake individuals, healthy sleepers, and narcolepsy type 1 patients, revealing how hypocretin deficiency affects cerebrospinal fluid dynamics.

bioRxiv · Jan 27, 2025 · PreprintNeuroscience

Sleep increases propagation speed of physiological brain pulsations

Ahmed Elabasy, Heta Helakari, Tommi Väyrynen, Zalán Rajna, Niko Huotari, Lauri Raitamaa, Ville Isokoski, Matti Järvelä, Mika Kaakinen, Johanna Piispala, Mika Kallio, Vesa O. Korhonen, Tapio Seppänen, Vesa J. Kiviniemi

The paper measures CSF flow velocity during sleep and finds it increases due to stronger vasomotor and respiratory pulsations, while cardiovascular speed remains unchanged.

bioRxiv · Jan 9, 2025 · PreprintNeuroscience

Vasomotor Pulsation Becomes a Driver of Cerebrospinal Fluid and Electrophysiological Dynamics in Sleeping Human Brain

Tommi Väyrynen, Johanna Tuunanen, Heta Helakari, Ahmed Elabasy, Vesa O. Korhonen, Niko Huotari, Johanna Piispala, Mika Kallio, Maiken Nedergaard, Vesa J. Kiviniemi

The paper investigates how vasomotor pulsation drives cerebrospinal fluid and electrophysiological dynamics during sleep in humans.

bioRxiv · Oct 16, 2024 · PreprintNeuroscience

Cardiovascular and vasomotor pulsations in the brain and periphery during awake and NREM sleep in a multimodal fMRI study

Johanna Tuunanen, Heta Helakari, Niko Huotari, Tommi Väyrynen, Matti Järvelä, Janne Kananen, Annastiina Kivipää, Lauri Raitamaa, Seyed-Mohsen Ebrahimi, Mika Kallio, Johanna Piispala, Vesa J. Kiviniemi, Vesa O. Korhonen

This study examines cardiovascular and vasomotor pulsations in the brain and periphery during awake and NREM sleep using fMRI and photoplethysmography, finding increased synchrony and power in vasomotor waves during sleep.

Frontiers in Neuroscience · Oct 8, 2024Peer-reviewedNeuroscience

Sleep specific changes in infra-slow and respiratory frequency drivers of cortical EEG rhythms

Tommi Väyrynen, Heta Helakari, Vesa O. Korhonen, Johanna Tuunanen, Niko Huotari, Johanna Piispala, Mika Kallio, Lauri Raitamaa, Janne Kananen, Matti Järvelä, Jaakko Matias Palva, Vesa J. Kiviniemi

This study investigates how infra-slow fluctuations and respiratory rhythms influence fast cortical EEG oscillations during wakefulness and sleep, finding that slow signals drive fast oscillations with stronger coupling during sleep.

bioRxiv · Jan 20, 2023 · PreprintNeuroscience

Sleep-specific changes in physiological brain pulsations

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

This study quantifies how sleep affects physiological brain pulsations and shows that spectral entropy of these pulsations can distinguish sleep from awake states.

bioRxiv · Sep 3, 2020 · PreprintNeuroscience