MB-EPI-comparison

This 3T fMRI dataset was collected in order to evaluate different multiband sequences at the Spinoza Centre for Neuroimaging (location REC, Amsterdam, The Netherlands).

## Contents
Each subject contains data from one session, in which a single working memory task was performed with different EPI sequences, indicated by the `acq` identifier:
* SeqMm3Tr2000: sequential (non-multiband) EPI, spatial resolution 3 mm. isotropic, TR of 2000 ms.;
* Mb4Mm2Tr1600: ultiband factor 4 EPI, spatial resolution 2 mm. isotropic, TR of 1600 ms.;
* Mb4Mm27Tr700: multiband factor 4 EPI, spatial resolution 2.7 mm. isotropic, TR of 700 ms.;
* Mb4Mm3Tr550: multiband factor 4 EPI, spatia resolution 3 mm. isotropic, TR of 550 ms.

Each subject contains two T1-weighted anatomical scans (one with axial slices, one saggital), one T2-weighted anatomical scans, a phase-difference fieldmap, four BOLD fMRI runs (corresponding to the four acquisition types listed above), and corresponding reverse-polarity ("topup") scans (to potentially compare B0-fieldmap based and topup-based unwarping). Additionally, physiology (*_physio.tsv.gz) is included for each corresponding BOLD fMRI run (converted from the Philips "SCANPHYSLOG" file using the "scanphyslog2bids" package; https://github.com/lukassnoek/scanphyslog2bids).

## Anonymity
In accordance with regulations from the University of Amsterdam, several precautions for participant anonymity were taken.
1. The informed consents signed by all participants contained a statement that their data could be shared with third parties;
2. No mapping from personal data (name, address, etc.) and subject identifier (e.g., sub-01) exists (and, in fact, never existed in the first place);
2. All structural data (T1-weighted scans) were defaced (using `pydeface`; https://github.com/poldracklab/pydeface);
3. Subject identifiers (sub-xx) were randomly shuffled

## Task
The “working memory” task used in this experiment was adapted from the task used in Pessoa, Gutierrez, Bandettini, and Ungerleider (2002). Participants were shown an
visual display with eight orientated bars, which after a delay period of 4 or 6 seconds was shown again with either an identical visual display or one with one bar changed in orientation. Participants had to report whether the display changed or not ("active" trials). In addition to these “working memory” trials, the task included 8 "control" trials (in which there was no visual display, but participants had to respond with a random button press) and 18 null trials. Thus, this experiment contained three primary conditions: active (targed changed), active (target did not change), and passive (control trial). See the `task-wm_events.json` file for more information about how these conditions (and additional information) is coded in the `*_events.tsv` files.

Trial order was identical for all participants.

Reference:
Pessoa, L., Gutierrez, E., Bandettini, P. A., & Ungerleider, L. G. (2002). Neural correlates of visual working memory: fMRI amplitude predicts task performance. *Neuron, 35* (5), 975-987.