Mattock made 29 appearances for West Brom during last season's promotion campaign but has not featured in the Premier League.
His parent club do not have an option to recall Mattock during his loan spell.
Former Republic of Ireland Under-21 international Lowry has spent much of his Villa career out on loan, making 24 appearances during spells at Plymouth Argyle and Leeds United.
Speaking about Lowry's arrival, Adams added: "He is young, enthusiastic, fits the profile we are looking for and I have watched him recently for Villa reserves.
"He had a good loan spell at Leeds United last season so coming to a club like ours won't faze him."
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