How does Shakespeare present Macbeth's state of mind in act 3, scene 4?

In this scene, Macbeth is attempting to conduct himself with the appropriate bearing and grace of a lord welcoming guests, but he feels "cabin'd, cribb'd, confined, bound into saucy doubts and fears," knowing that he is responsible for more than one murder while fighting to keep this from being obvious.
When the ghost of Banquo enters, Macbeth is immediately afraid that he has been found out—we see his anxiety when he says, "Which of you have done this?" The others present at the dinner, being unable to see the ghost, are confused, but Macbeth continues to become more agitated, addressing the ghost directly and saying that it should not "shake [its] gory locks" at him. He disavows responsibility. This is an interesting section in the play because only Macbeth seems able to see the ghost; Lady Macbeth says Macbeth is looking "but on a stool." Unlike in Hamlet, there is good reason for the director to contemplate whether or not to actually show a ghost; arguably, the ghost of Banquo is simply Macbeth's own guilty conscience expressing itself to him and him alone.