Brainlet

Let's call these five smaller brain units, brainlets: […] Each brainlet is found in a specific part of your thinking brain.

Source: wiktionary

The Prof brainlet is the IT brainlet. The Prof embraces pure logic without the “messiness” of emotion or instinct. To The Prof, everything is objective and impersonal.

Source: wiktionary

...viz. the railway : an invention which is so thoroughly English that, even supposing it likely to have occurred to any slow Prussian brainlet, it would still have been impossible to have found any other nation (excepting perhaps America) with spirit or capital sufficient to have afforded the plan a trial.

Source: wiktionary

But a shade of bygone sorrow, Like a dream upon the morrow, Round his tiny brainlet clinging, Sets the wee cock ever singing,

Source: wiktionary