How does "The Cask of Amontillado" comment on psychological freedom and confinement?

You have certainly identified that psychological freedom
and confinement are key aspects of this masterfully gothic tale. It is worth thinking
about the kind of writing that Poe produced before answering this question. Poe was
known as a "Dark Romantic", which means he was one of a group of authors who focussed
their work on the dark side of humanity - evil, sin and the capacity within us all to do
terrible things.

Clearly, this becomes a useful context in
which to place this story. We are introduced to a narrator, who, we go on to suspect, is
unreliable, in that we begin to doubt what he professes to us. Consider how the story
begins:

The
thousand injuries of Fortunato I had borne as best I could; but when he ventured upon
insult, I vowed revenge.

We
begin to wonder about the accuracy of the narrator's perception when we see the trust
that Fortunato displays to Montresor - if he had indeed, "ventured upon insult", he
might not have been so quick to fall in to Montresor's
trap.

It is clear that we are seeing the narrator beneath
his mask of public respectability. The setting of the story is key in this respect too -
it is set during carnaval, when characters wore masks and fine clothing. It is perhaps
ironic that Montresor chooses this time to reveal his true inner
self.

Note too, the symbolic function of the catacombs.
Consider how they are described:

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We had passed through walls of piled bones, with
casks and puncheons intermingling, into the inmost recesses of the
catacombs.

As Montresor leads
Fortunato on into the ever-deeper depths of the labyrinthine catacombs, we as readers
are treated to a special voyage into the psychological state of Montresor - the deeper
we get, the more devilish, sadistic and horrific his thinking and actions become. It is
key that Montresor commits his heinous crime once they have penetrated the depths of the
catacombs and reached the finish - he is able to express his psychologically disturbed
state to the extreme. Yet, to return to your question, I wonder whether the bricking-in
of Fortunato represents the psychological repression of Montresor's evil desires and
actions - we can only assume that after chillingly sealing in Fortunato and leaving him
there to die, Montresor is able to put on his mask of respectability and operate in
Venetian society once more. Having "buried" his unacceptable psychological side he can
freely partake of "normal" society again.