Should a comma follow the noun

Question

Please can someone explain why, when there is an inverted question and the subject is a noun, there is not a comma after the subject, as I was taught when I learned French at school?

Answer

Hi George, 
A comma ( une virgule) denotes a pause and works pretty much as in English. 
In all the examples in this lesson there are no commas which is correct as in the example given by Le Petit Grevisse - 
L'accusée dit-elle la vérité ? = Does the accused speak the truth?
but it could have been -
Marie va-t-elle au marché ? = Is Marie going to the market?
The only case which I know when you would have a comma in these types of sentences- statements, or inverted questions - would be after a stress pronoun -

Lui, s'appelle-t-il Henri ? = Is his name Henry?
Son frère va venir mais elle, ne viendra pas = Her brother is going to come but she won't be coming
Eux, ils arriveront demain matin = They'll arrive tomorrow

Hope this helps!