• Cyril Atkinson-Clement, Mohammad Alkhawashki, Marilyn Gatica, Stefanos Alexandros Kontogouris, and Marcus Kaiser.
• Precision Imaging, School of Medicine, University of Nottingham, Nottingham, UK; National Institute for Health and Care Research Biomedical Research Centre, University of Nottingham, Nottingham, UK. Electronic address: Cyril.Atkinson-Clement@nottingham.ac.uk.
• Neuromodulation. 2025 Feb 6.

ObjectiveDespite the growing interest in transcranial focused ultrasound stimulation (TUS), our understanding of its underlying mechanisms remains limited. In this study, we aimed to investigate the effects of TUS on several functional magnetic resonance imaging metrics by considering their latency, duration, and relationship with applied acoustic pressure.Materials And MethodsWe recruited 22 healthy volunteers and used a pre- vs post-TUS protocol. Half of the volunteers were stimulated in the right inferior frontal cortex and the other half in the right thalamus. The fractional amplitudes of low-frequency fluctuations, regional homogeneity, degree centrality, local functional connectivity density, and eigenvector centrality were considered. These metrics were compared before TUS and at three different time points in the first hour after TUS.ResultsOur results showed that 1) TUS primarily alters functional connectivity metrics at both the local and global levels; 2) stronger alterations are observed when the delay after TUS increases and 3) when the applied acoustic pressure is close to the maximum.ConclusionThese results suggest that some consequences of TUS might not be immediate, inviting us to revise the premise that TUS consequences are immediate and will progressively disappear.Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.

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