While the disability to work resulting from an injury is temporarily total, the employer shall pay or cause to be paid to the employee a weekly benefit equal to two-thirds of the employee's average weekly wage but not more than $575.00 per week nor less than $50.00 per week, except that when the weekly wage is below $50.00, the employer shall pay a weekly benefit equal to the average weekly wage. The weekly benefit under this Code section shall be payable for a maximum period of 400 weeks from the date of injury; provided, however, that in the event of a catastrophic injury as defined in subsection (g) of Code Section 34-9-200.1, the weekly benefit under this Code section shall be paid until such time as the employee undergoes a change in condition for the better as provided in paragraph (1) of subsection (a) of Code Section 34-9-104.