Welcome to the board. There is a wealth of information to be found and shared here. It's one of the best sites of it's kind. That said, lets see if we can enlighten you on migration movements of bass. 'Buck' Perry did shed a lot of light on the subject along with a ton of information about structure and the above mentioned book along with 'Lunkers Love Nightcrawlers' are a must read for anyone wanting to understand that subject.
To begin with, bass that call shallow water their home during the summer don't migrate. The same goes for schooling bass as the majority of their movements during the summer are in relation to the forage movements such as shad schools. If the forage moves shallow the schoolies will too, but that isn't a true migration.
Migration refers to the movement of deep water fish from their deep water to the shallows and back. There is a seasonal migration to the shallows for the spawn and during the summer, a migration for feeding. The feeding migration can occur anywhere from twice daily to only once in a two or three day period. The availability or lack of deep water forage and frontal conditions have the biggest effect on frequency.
That movement is typically governed by structure, which those fish use similar to a road, that extends from the shallows to the deeper water. This is the reason why understanding structure is important to us. One thing to remember about this migration route that they use; Often, the fish will not make the complete journey to the shallows. For a number of different reasons they will stop somewhere along that path and then return to the depths. This can be an extended stop or it can last an hour or less. Again, forage availability and frontal or barametric pressure conditions are two of the factors that determine their length of stay.
As an example: There is a point that extends from a feeding flat out to deep water. One side of the point drops faster than the other and on that side of the point are a rock pile and an area where the bottom changes from soft bottom to sand or small gravel. The weeds stop growing at that point.
The point is the major structure in this example. The rock pile and the transition area are types of structure also, but in this instance they serve as 'rest stops' for fish migrating to the shallows to feed. If that structure, or the cover associated with it, holds forage there is no need for them to move shallower. If the point holds no 'rest stop' structure or cover, they would continue moving up to the shallows and return after feeding.
That is a simple example of a migration route. Hope that helps.