Final answer:
The primary developments of the bird brain involve advances in the primary vesicles, namely the prosencephalon and rhombencephalon.
Step-by-step explanation:
The primary developments of the brain of birds, including the corpus striatum and the midbrain, involve advances in the primary vesicles of the embryonic brain.
The prosencephalon, or forebrain, develops into the cerebrum and diencephalon. The cerebrum is responsible for higher cognitive functions, while the diencephalon includes structures such as the thalamus and hypothalamus.
The rhombencephalon, or hindbrain, develops into the pons, cerebellum, and medulla. The cerebellum plays a key role in motor coordination.