The following is a list of fMRI terminology commonly used to describe stimulation and task parameters and protocols. The list follows the terminology used by the Brain Imaging Data Structure (BIDS - https://bids.neuroimaging.io/) for structural and functional MRI.
Dataset. A collection of neuroimaging and behavioral data acquired for use in a specific study. The dataset may consist of data acquired from multiple subjects, possibly over the course of many sessions.
Data acquisition. An uninterrupted period of time in which the scanner was acquiring data according to a particular scanning sequence/protocol.
Data type. A grouping of different types of related data. These may include: func (for functional, task-based and resting state functional MRI), dwi (diffusion weighted imaging), fmap (field inhomogeneity mapping data like field maps), anat (for anatomical, which includes structural imaging such as T1, T2, weighted images etc.), meg (magnetoencephalography), beh (for behavioral data, for example collected from tasks using hand grips, eye tracking data, pain stimuli response, etc.).
Session. A grouping of neuroimaging and behavioral data that is consistent across participants. A session includes the time it takes to complete all experimental tasks. This usually begins when a participant enters the research environment for the day or segment of the day until they leave it. However, if a subject must leave the scanner room and then be re-positioned on the scanner bed, the MRI acquisitions will still be considered to be one session and match sessions acquired in other subjects (although this should be documented in the lab book, as it may impact pre-processing and analysis). In situations where different data types are obtained over several visits (for example fMRI on one day and EEG on the next) they may be grouped in one session. A session typically starts with obtaining informed consent and completing the MRI safety checklist. It generally ends when the participant is removed from the scanner, but can also include a number of pre- or postobservations and measurements (e.g., additional behavioral or clinical testing, blood tests, questionnaires, EEG, etc.).
Task. A set of activities performed by the participant while in the scanner. Tasks usually involve stimuli and responses. Resting state scans should also be considered a task. A task is always performed in connection to one data acquisition. Even if during one acquisition the subject performed multiple conceptually different behaviors (with different sets of instructions) they will be considered one (combined) task.
Run. A continuous period of data acquisition that has the same acquisition parameters and task (however events may change from one run to another in relation to different subject responses or because of randomized presentation of the stimuli). A run is essentially the same as data acquisition.
Event. An isolated occurrence of a stimulus being presented, or a response being made. It is essential to have exact onset timing and duration information in addition to identify the events and when they occurred. Some tasks will not have events however (for example, resting state).