Your are confounding two issues. One bit of IP is the copyright assignment for the article itself. Typical for-pay journals require assignment in order to pub

Your are confounding two issues. One bit of IP is the copyright assignment for the article itself. Typical for-pay journals require assignment in order to publish (i.e. they at minimum own the publishing rights moving forward). The various bits of IP that can be assigned for the work/discoveries you did vary very much from institution to institution, and may vary with the source of funding. Nothing is really simple here, an it runs the gamut from the investigator owning everything to the investigator owning nothing other than attribution, etc. rights