NEUROTRANSMITTER BASIS OF BEHAVIOR IN A M OLLUSK - CONTROL OF CHOICE BETWEEN SEARCHING AND DEFENSIVE RESPONSES TO A NOVEL OBJECT

The role of serotonin and opioid peptides in decision making was studi ed in the pond snail Lymnaea stagnalis. It was shown that 5-HTP increa sed the number of searching responses to a sudden presentation of a no vel object. Opiate antagonist naloxone decreased the number of searchi ng responses and increased the number of defensive and escape reaction s; The effect of 5-HTP and naloxone on decision making appear to be co ordinated with their effects on their behavioural state.