Findings with reasonable support
Altered states involve measurable changes in connectivity, sensory gating and self-referential processing. Psychedelics reliably disrupt default-mode network integrity. Rhythmic sensory driving affects cortical entrainment.
Findings that are weaker than commonly claimed
Specific theta-drumming frequencies as a reliable trance switch; entoptic form-constant models as proof of prehistoric shamanism; neurotheology mapping a dedicated 'spiritual' brain region. Each is contested and none should be presented as settled.
The category error to avoid
Describing the neural correlates of an experience explains neither its meaning nor its truth-claim. A cultural practice is not reduced by being embodied.