Brewer et al. · 2011 · Observational fMRI
Three meditation practices in MRI
Experienced meditators and matched naive controls practiced concentration, loving-kindness and choiceless awareness. Experienced meditators showed relative deactivation in major default-mode regions and different connectivity involving attention and control-related areas.
What it supports: a relationship between meditation experience, active practice and network activity. The design does not show that reducing a region's activity causes meditation or flow.
Meditation experience is associated with differences in default mode network activity and connectivity · PNAS ↗
Garrison et al. · 2013 · Real-time fMRI feedback
Focused attention with PCC feedback
Participants viewed a real-time graph from posterior cingulate cortex while practicing focused attention. Experienced meditators could deliberately decrease the signal in the first experiment; novices did not show the same significant regulation. A separate experienced group replicated the pattern through a discovery protocol.
What it supports: a way to connect a measured response with ongoing experience and voluntary regulation. It does not establish durable learning or a flow-induction treatment.
Real-time fMRI links subjective experience with brain activity during focused attention · NeuroImage ↗
van Lutterveld et al. · 2016 · EEG feedback · 32 participants
Effortless awareness with source-space EEG
Sixteen novices and sixteen experienced meditators received feedback based on a beamformer estimate of PCC gamma activity at 40–57 Hz. Both groups linked decreases with effortless awareness and could voluntarily regulate the signal in that direction.
What it supports: feasibility of an EEG version of a PCC-focused feedback task. Source estimation and artifact control are part of the method; a new headband does not inherit the result by showing gamma power.
Source-space EEG neurofeedback links subjective experience with brain activity during effortless awareness meditation · NeuroImage ↗
Yu et al. · 2025 · Randomized active/sham fMRI feedback
Mindfulness feedback tested against sham
Of 43 adolescents exposed to early-life adversity, 22 received active PCC feedback and 21 artificial feedback during breath-focused mindfulness. Forty healthy comparison adolescents also participated. Active feedback did not outperform sham on PCC downregulation or the reported self-report measures.
What it supports: feasibility and an important limit on added benefit in this population and design. Improvements with a training task do not automatically demonstrate a specific neurofeedback effect.
Posterior cingulate cortex downregulation training using fMRI neurofeedback in adolescents with early life adversity exposure · Translational Psychiatry ↗
Ulrich et al. · 2014 · MRI perfusion · 27 participants
Flow during adaptive arithmetic
Arithmetic difficulty continuously adjusted to skill, with boredom and overload as comparisons. Flow was associated with increased responses in left inferior frontal cortex and putamen, and reduced responses in medial prefrontal cortex and amygdala.
What it supports: task-related flow has a distributed pattern with increases and decreases. This was imaging of flow correlates, rather than a feedback or stimulation experiment.
Neural correlates of experimentally induced flow experiences · NeuroImage ↗
Katahira et al. · 2018 · EEG correlates · 16 participants
Higher theta and moderate alpha
EEG and flow ratings were measured during boredom, flow and overload arithmetic conditions. Frontal theta was higher during both flow and overload than boredom. Flow combined higher frontal theta with moderate frontocentral alpha; alpha increased with task difficulty.
What it supports: considering multiple EEG features and task context. Higher theta alone was not a unique flow signal, and the study did not train or stimulate the pattern.
EEG Correlates of the Flow State: A Combination of Increased Frontal Theta and Moderate Frontocentral Alpha Rhythm · Frontiers in Psychology ↗
Eschmann et al. · 2022, online 2021 · EEG feedback · 48 participants
Theta training and reported flow
Everyone received a thirty-minute frontal-midline-theta neurofeedback session. The authors compared 25 responders with 23 non-responders. Training gains were associated with finger-tapping improvement and increased flow ratings, including an association beyond the corresponding motor gain. Transfer to an n-back task was not significant.
What it supports: a direct hypothesis for theta feedback and flow. Responders were not a randomized active group against a sham group; the authors describe the evidence as mainly correlational.
Theta Neurofeedback Training Supports Motor Performance and Flow Experience · Journal of Cognitive Enhancement ↗
Gold and Ciorciari · 2019 · Active/sham tDCS · 2 small experiments
Stimulation during game play
Eleven trained first-person-shooter players completed active and sham sessions in randomized order; 21 untrained Tetris players were randomized between conditions. The authors reported higher flow ratings with active tDCS in both experiments. Performance gains appeared in untrained players.
What it supports: further controlled work on stimulation and flow. Small samples, different games and different designs limit generalization. This did not demonstrate EEG-guided phase entrainment.
A Transcranial Stimulation Intervention to Support Flow State Induction · Frontiers in Human Neuroscience ↗
Helfrich et al. · 2014 · Simultaneous EEG/tACS · 14 participants
Alpha timing and visual detection
During an alpha-frequency tACS and visual task, the authors reported parieto-occipital alpha modulation, synchronization and phase-dependent target detection. Their analysis used concurrent EEG with stimulation-artifact removal.
What it supports: a specific oscillation-and-perception experiment. Flow and meditation were not measured. Concurrent-stimulation results need artifact validation; they do not establish a general flow frequency.
Entrainment of brain oscillations by transcranial alternating current stimulation · Current Biology ↗
Vossen et al. · 2015 · Intermittent tACS · 12 participants
Aftereffects can reflect plasticity
Intermittent alpha-frequency stimulation produced alpha-power aftereffects without the expected phase-continuity dependence or prolonged phase alignment of an entrainment echo. The authors concluded that plasticity mechanisms could account for the aftereffects.
What it supports: separating persistent power changes from continued phase locking. Neither a larger EEG peak nor an aftereffect by itself proves that an intended state was entrained.
Alpha Power Increase After tACS at Alpha Frequency Reflects Plastic Changes Rather Than Entrainment · Brain Stimulation ↗
Sources checked 28 October 2026. The library includes observational findings, feasibility work, controlled comparisons and mechanistic experiments; those designs answer different questions. The companion qualitative MRI paper is linked above.