To maximize BIDS compliance we should add a top-level _physio.json file in each dataset with :

• Manufacturer RECOMMENDED string Manufacturer of the equipment that produced the measurements.
• ManufacturersModelName RECOMMENDED string Manufacturer's model name of the equipment that produced the measurements.
• SoftwareVersions RECOMMENDED string Manufacturer's designation of software version of the equipment that produced the measurements.
• DeviceSerialNumber RECOMMENDED string The serial number of the equipment that produced the measurements. A pseudonym can also be used to prevent the equipment from being identifiable, so long as each pseudonym is unique within the dataset.

Biopac
MP160
Acknowledge xx.yy
SerialNumber -> to be looked up downstairs if not in the acq files headers.

Also add more verbose columns descriptions ( such as describing ECG or EDA or PPG electrode types/ placement on the body/ signal-specific amplifier module... and specifying units if we can have it) with additional fields as in this example in the spec:

{
    "SamplingFrequency": 100.0,
    "StartTime": -22.345,
    "Columns": ["cardiac", "respiratory", "trigger"],
    "Manufacturer": "Brain Research Equipment ltd.",
    "cardiac": {
        "Description": "continuous pulse measurement",
        "Units": "mV"
        },
    "respiratory": {
        "Description": "continuous measurements by respiration belt",
        "Units": "mV"
        },
    "trigger": {
        "Description": "continuous measurement of the scanner trigger signal"
        }
}

For the columns name + description, it is not possible to comply to the BIDS standards because they actually do not account for different type of cardiac signals (i.e. PPG vs ECG). Also, they don't provide a standard column name for EDA...

IIUC, these are the column name so for us:

    "Columns": [
        "time",
        "EDA",
        "PPG",
        "ECG",
        "TTL",
        "RSP"
    ]

which should have a top-level json with something like:

{
...
"EDA": { 
       "Description": "continuous skin conductance measure",
        "Units": "AU"},
"PPG": {       "Description": "continuous pulse measurement",
        "Units": "whatever"} 
}

BTW: why do we have a column "time".
Can't we just use SamplingFrequency+StartTime to determine the time relative to fMRI?
If that's a column with a fixed increment (of 1/SamplingFrequency s) that's a lot of data for nothing.

My 2 cents on the issue of the time column: it is negligible in terms of data size, and easier to parse for users than some kind of meta-data start time + sampling time. If we end up dropping frames as part of preprocessing, this format can also accomodate irregular grids. Is it something that is covered by the BIDS extension?

@all-contributors please add @me-pic for data preparation

@bpinsard

I've put up a pull request to add @me-pic! 🎉