Brain imaging can reveal anatomy, patterns related to activity and certain molecular processes. Different technologies answer different questions, so a colorful brain image is not a complete explanation of how someone thinks, feels or responds to treatment.

Structure and function are different measurements

Structural MRI can show detailed anatomy. Functional MRI commonly uses changes related to blood oxygenation as an indirect indicator of activity. It does not directly count thoughts or measure every neuron firing. NIBIB: Magnetic resonance imaging

PET uses tracers to investigate particular biological targets or processes. Its interpretation depends on the tracer, model and analysis. A signal associated with an inflammatory target, for example, should not be treated as a universal measurement of all neuroinflammation.

Group differences are not automatic individual diagnoses

An average difference between study groups may overlap substantially at the individual level. Motion, analysis choices, sample size and multiple statistical comparisons can also influence findings. Replication and appropriate controls are essential.

Functional connectivity describes statistical relationships between signals in different regions. It does not necessarily demonstrate a direct anatomical connection or prove that communication has become better.

Why a changed scan is not enough

A small study of Semax and Selank reported short-term changes in resting-state connectivity. Those measurements did not by themselves establish improved memory, reduced anxiety or long-term benefit. Panikratova and colleagues, 2020

The strongest research links imaging to well-defined clinical or behavioral outcomes and explains what the technique cannot show. Brain imaging is powerful because it adds a layer of evidence. It should not be used as a visual shortcut around the need to demonstrate meaningful benefit.