Section 59. There is hereby established on the books of the commonwealth a separate fund known as the Head Injury Treatment Services Trust Fund. Said trust fund shall consist of monies paid to the commonwealth pursuant to sections 20 and 24 of chapter 90, sections 8 and 34 of chapter 90B and any interest or investment earnings on such monies, except for monies deposited in the Thomas P. Kennedy Spinal Cord Injury Trust Fund under section 59A. The state treasurer, ex officio, shall be the custodian of said trust fund and shall receive, deposit and invest all monies transmitted to him under the provisions of this section and shall credit interest and earnings on the trust fund to said trust fund. Funds collected pursuant to said section 24 shall be expended without further appropriation for the purpose of developing and maintaining nonresidential rehabilitation services for head injured persons in such manner as the commissioner of rehabilitation may direct. Funds collected pursuant to said section 20 shall be expended without further appropriation for the purpose of developing and maintaining residential and nonresidential rehabilitation services for head injured persons in such manner as the commissioner of rehabilitation may direct. In order to ensure that said services established by the commissioner continue without interruption, the comptroller may certify for payment amounts in anticipation of revenues collected for the corresponding quarter during the previous fiscal year.