BEHAVIORAL DECREMENTS PERSIST IN RHESUS-MONKEYS TRAINED ON A SERIAL PROBE RECOGNITION TASK DESPITE PROTECTION AGAINST SOMAN LETHALITY BY BUTYRYLCHOLINESTERASE

Recently, it has been demonstrated that an exogenously administered en zyme such as butyrylcholinesterase (BuChE) can prevent death in rhesus monkeys exposed to multiple-lethal doses of the acetylcholinesterase inhibitor soman when the enzyme is given prior to soman exposure (3). We report that despite BuChE protecting against soman-induced lethalit y, behavioral effects are seen in these monkeys which last for at leas t 6 days as measured by performance on a serial probe recognition (SPR ) task. Analyses of the serial position curves showed that performance was lower on the probe trials when the probe items were from the midd le of the list than when the probe items were from the beginning or en d of the list which were unaffected. BuChE given alone also produced b ehavioral effects, causing all animals not to respond on the probe tri als until 8 h following BuChE administration. Taken together, these fi ndings suggest that the BuChE is not completely binding all of the som an and that a concentration of soman which is capable of causing behav ioral effects may be entering the CNS.