They form stronger connections with each other than with other neurons and they develop more dendritic spines: protrusions that help neurons talk to each other.
Your mistake is in judging existence by its protrusion into matter as you are familiar with matter, and this attitude indeed will persist into any foreseeable future without basic change.
And the keel-like protrusion on their sternums, where the flight muscles attach, shrinks or disappears, except in penguins, who repurpose their flight muscles and keels for swimming.
Silent synapses - which, as their name suggests, transmit no signal from one nerve cell to another - are often found on the ends of slender, immature protrusions from nerve cells, called filopodia.
If all these conversation-like games, gestures, and tongue protrusions really do relate to the same brain area, it could help support that language evolved from our hands to our mouths.