Neuroimaging measures structural or functional properties of the nervous system. Different methods record different physical signals, so anatomical images and activity-sensitive measurements support different inferences.
For example, electroencephalography records electrical potential differences, while many functional vascular measurements depend on neurovascular coupling. Spatial overlap in an image is not by itself proof that one location implements a complete psychological process.
The relationship between neural activity and local vascular responses underlying many functional imaging measurements. Disease-related changes in this relationship complicate direct comparisons of activation magnitude.
Imaging a calcium-sensitive signal as an indirect measure related to cellular activity. Indicator kinetics, neuropil contributions and movement can affect its relationship to spikes.
Optical measurement of a fluorescent signal collected from a tissue volume. It can report population calcium or transmitter-sensor dynamics depending on the reporter; it is not automatically a single-neuron spike train.
Magnetoencephalography measures very small magnetic fields generated by electrical activity in neural tissue. It supplies a time-resolved signal that can constrain when activity changes relative to an event.
Inferring its neural sources is an inverse problem: sensor readings combine contributions from multiple locations and depend on their geometry. The technique therefore does not directly display the activity of one isolated neuron.
Electroencephalography records differences in electric potential using electrodes, commonly at the scalp. Summed activity in neural tissue contributes to the measured signal, providing millisecond-scale information about changes over time.
An event-related potential compares or averages this activity relative to defined events. Volume conduction and overlapping sources limit direct localization, so a scalp waveform cannot simply be equated with one small neural generator.
A sustained lateralized electrophysiological signal during visual-memory delays, typically measured as a difference between signals contralateral and ipsilateral to the attended visual field. Its load dependence and relation to behavioral capacity constrain models without fixing a universal storage count.
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Neuroimaging refers to a variety of techniques used to visualize the structure, function, and activity of the brain and nervous system. These methods allow researchers and clinicians to observe the brain in both healthy and diseased states, aiding in the understanding of its anatomy, functioning, and the pathology of neurological and psychiatric disorders.