The 24-year-old USA international winger has moved to St Andrews on a three-month emergency loan.
"I've been chasing Brek for a while and actually wanted to sign him permanently at the start of the season," manager Lee Clark told the club's official website.
"He impressed me when he played for Barnsley here at St Andrew's on New Year's Day and, given our recent injuries, it made sense to make this loan move, importantly with no recall clause being something that I have stressed all along."