tokens: While nocistatin ( 0 . 5 - 5 . 0 nmol mouse - 1 , i . c . v . ) administered 30 min before spontaneous alternation performance or the training session of the passive avoidance task , had no effect on spontaneous alternation or passive avoidance behaviours , a lower per cent alternation and shorter median step - down latency in the retention test were obtained in nociceptin ( 1 . 5 and / or 5 . 0 nmol mouse - 1 , i . c . v . ) - treated normal mice .