"while listening to operatic solos, musicians process the lyrics and the melodies in separate brain areas. this most clearly illustrates the functioning of different neural "

The musicians process the melodies and the lyrics while listening to the operatic solos in the different areas of the brain. The neural network of the brain is quite complex, and the different activities follow different neural pathways. In the listening of the operatic solos, the lyrics and the melodies of the song are processed in the different part of the brain, and hence, different neural networks function during this processing.

Hence, the blank can be filled with 'neural networks'.

the truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey.