How are sequential patterns grouped into meaningful objects in the brain?
The key here is the Gestalt principle formulated in the early 1900's consists of a set of 'laws' describing how perception elements are grouped into recognized objects. The Gestalt laws "prescribe for us what we are to recognize 'as one thing'". Recent data support this view (Pelli et al., 2009).

On a more fundamental level working memory is essential in this process. It is a form of short term memory. An example where short-term memory comes into play is when information is cut up in pieces, like in your example - 'Chunking' is the organization of material into shorter meaningful groups to make them more manageable.

Short-term memory is supported by transient patterns of neuronal communication in the regions of the frontal, prefrontal and parietal lobes of the brain. Long-term memories are maintained by more stable and permanent changes in neural connections widely spread throughout the brain. 

The hippocampus temporarily stores information and gates it to the long-term memory. Typically, information is transferred from the short-term working memory to the long-term memory within just a few seconds, 

Reference
- Pelli et al., Cogn Neuropsychol (2009); 26(1): 36-49