What kind of processes are "top-down" and "bottom-up" processes in the context of processing visual information in brain?
...There are discrete areas in the visual cortex dedicated to identifying specific aspects of vision – vertical or horizontal lines, colour or movement, for example. These elements are brought together to ensure that the total image arrives consistently in space and time. And even while our brains are swiftly adjusting to focus on the scene before us, images established in memory form feedback loops to confirm that we recognise what we have seen before, mediating prior knowledge into perception. As we acquire this personal knowledge then, we impose ‘top-down’ concepts on to ‘bottom-up’ perceptions. When we look at a cluttered scene in front of our eyes we may receive only partial information but our brains automatically fill in the gaps to make sense of things.