User accounts may include a small user picture. It can be a real image or an icon. Optionally, user pictures may be included on news items, comments, and forum posts. These personalize an account and can emphasize a community. They can also be annoying, and particularly when users abuse them with dumb images or animated GIFs.
... there would be a use for an image allowance to share and/or ask about a 3-D EEG measure ...
Files, images, and folders uploaded by users, and eventually published, are all included in the file/folder list under the "Files" menubar item. These are managed separately from administrative content, such as a user's image attached to their account. So, while uploaded files might be subject to a future quota system, the user image on the account won't be included.