Method for improving primary memory and/or learning

A method for improving primary memory or learning in a mammal, comprising administering to a mammal in need of primary memory or learning improvement a 4-amino benz[cd]indole selected from the group (.+-.)-4-(di-n-propyl)amino-6-methoxy-1,3,4,5-tetrahydrobenz[cd]indole, (.+-.)-6-acetyl-4-(di-n-propylamino)-1,3,4,5-tetrahydrobenz[cd]indole, (.+-.)-6-(2,2-dimethylpropanoyl)-4-(di-n-propylamino)-1,3,4,5-tetrahydrobe nz[cd]indole, (2aS,4R)-,(2aR,4S)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydroben z[cd]-indole, (2aR,4R)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[cd]indol e, (2aS,4S)-6-acetyl-4-(di-n-propylamino)-1,2,2a3,4,5-hexahydrobenz[cd]indole , (+)-(2aS,4R)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[cd] indole, (-)-2aR,4S)-6-acetyl-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz[cd]in dole, (+)-(2aS,4R)-6-(2-methylpropanoyl)-4-(di-n-propylamino)-1,2,2a,3,4,5-hexah ydrobenz[cd]indole, (+)-(2aS,4R)-6-(benzoyl)-4-(di-n-propylamine)-1,2,2a,3,4,5-hexahydrobenz[c d]indole, and (+)-(2aS,4R)-6-(propanoyl)-4-(di-n-propylamino)-1,2,2a,3,4,5-hexahydrobenz [cd]indole, or a pharmaceutically acceptable salt thereof, which is a 5-hydroxytryptamine receptor agonist selective for the 5-hydroxytryptamine-1A subtype, at a dose effective for improving primary memory or learning.