When trying to understand a circuit, I often look for visually similar circuits, but even though I have found several OTA filters, they are always different from the Juno one. But here is the clue: These are similar:
|The typical Roland filter cell to the left, its equivalent to the right.|
The cell is really quite simple - the resistors, 68k and 560Ohm function as voltage dividers to reduce the input signal to the OTA. This is true for both the 68k on the input and the 68k in the feedback loop.