One of the things that I find most poignant about this episode is that the disease actually makes Spock revert back to his childhood. Nimoy’s acting is brilliant here; look how childish his mannerisms are, the way he holds himself, the way he wipes his tears in the fourth gif. Look how weak he suddenly seems when he collapses against the doorway. And then he recites the times tables, of all things, in order to steady himself, which indicates that he’s regressed quite far (I memorized the times tables when I was eight or nine, but Vulcan children probably start much younger). And most gut-wrenchingly of all, he says (to whom?), ‘I’m sorry.’
The mechanical recitation of a prepared mantra–'I am in control of my emotions’–is evidence that all of this has happened before. We know Spock is under the influence of a disease that tears down people’s mental barriers and forces emotional responses, so it makes sense that he would mentally regress to the age when he started repressing his emotions in the first place. This must have been around the time he was taken out of his (human) mother’s care and put into (Vulcan) school. This scene is giving us a privileged glimpse into the difficulty of that transition.
How human had little Spock already grown under Amanda’s influence? Did she allow him to laugh and cry (as all human children do)? Did she encourage physical displays of affection, or flights of fancy? At any rate we know the passage into Vulcan culture must have been very difficult and demanding for Spock because he was reprimanded for many mistakes, or he would not have automatically apologized out of habit, even when there was no one around to hear him.