US EditionStudy Finds 40% of fMRI Brain Scans Misread Neural Activity
Researchers at TUM and FAU found that about 40% of fMRI BOLD signals inversely reflect neural activity, challenging decades of brain disorder interpretations and AI model training.
- On December 12, 2025, researchers at the Technical University of Munich and Friedrich-Alexander-University Erlangen-Nuremberg published that about 40% of fMRI signals contradict actual brain activity.
- Neurovascular coupling — the mechanism linking neuronal activity to cerebral blood flow — is correct about 60% of the time, as many brain regions meet energy demand by increasing oxygen extraction fraction instead of blood flow.
- Using a novel quantitative MRI, the team measured oxygen consumption and BOLD signals in over 40 healthy participants during mental arithmetic and memory recall, revealing physiological variations by region and task.
- Immediate consequences include tens of thousands of published fMRI studies, including clinical research on depression and Alzheimer’s, requiring reinterpretation, while AI/machine learning developers using fMRI datasets and brain-computer interfaces face training label errors up to 40%.
- To address this, researchers recommend complementing fMRI with Quantitative MRI and cross-validating with EEG and PET to enable future energy-based brain models mapping oxygen consumption.
12 Articles
12 Articles
BOLD signal changes can oppose oxygen metabolism across the human cortex
Functional magnetic resonance imaging measures brain activity indirectly by monitoring changes in blood oxygenation levels, known as the blood-oxygenation-level-dependent (BOLD) signal, rather than directly measuring neuronal activity. This approach crucially relies on neurovascular coupling, the mechanism that links neuronal activity to changes in cerebral blood flow. However, it remains unclear whether this relationship is consistent for both p
40 percent of MRI signals do not correspond to actual brain activity
Contradiction to the prevailing paradigm in neuroimaging No general relationship between oxygen content and neuronal activity Conventional MRI method should be complemented by quantitative measurements For almost three decades, functional magnetic resonance imaging (fMRI) has been one of the main tools in brain research. Yet a new study published in the renowned journal Nature Neuroscience fundamentally challenges the way fMRI data ha…
40% of MRI signals do not correspond to actual brain activity, study suggests
For almost three decades, functional magnetic resonance imaging (fMRI) has been one of the main tools in brain research. Yet a new study published in Nature Neuroscience fundamentally challenges the way fMRI data have so far been interpreted with regard to neuronal activity.
Functional MRI signals can misrepresent true brain activity
Researchers at the Technical University of Munich (TUM) and the Friedrich-Alexander-University Erlangen-Nuremberg (FAU) found that an increased fMRI signal is associated with reduced brain activity in around 40 percent of cases.
40 Percent of MRI Signals Do Not Correspond to Actual Brain Activity
For almost three decades, functional magnetic resonance imaging (fMRI) has been one of the main tools in brain research. Yet a new study published in the renowned journal Nature Neuroscience fundamentally challenges the way fMRI data have so far been interpreted with regard to neuronal activity.
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