tokens: 5 , 7 - dichlorokynurenic acid ( 5 , 7 - DCKA ) , a selective glycine site antagonist , injected in doses of 2 . 5 and 4 . 5 microg / 0 . 5 microl bilaterally , into the rostral region of the striatum , decreased both the haloperidol - induced muscle rigidity ( MMG ) and the enhanced electromyographic activity ( EMG ) .