Table 2: Knockout mice models and memory performance.

Behavioral taskKnockout typeEffect on memoryReference(s)

Water maze*Hdc −/− [111]
Water mazeHdc −/−[112]
Object recognition*Hdc −/−Unaffected [111]
Nonreinforced episodic object memoryHdc −/−[112]
Contextual fear conditioningHdc −/− [113]
One-trial passive avoidanceHdc −/− [111]
Open field (habituation)Hdc −/−Unaffected[114]
Inhibitory avoidanceKO H1−/−Unaffected [115]
Conditioned place preferenceKO H1−/− [116]
Radial-maze taskKO H1−/−[117]
Auditory and contextual fear conditioningKO H1−/− [68]
Auditory and contextual fear conditioningKO H2−/− [68]
Object recognitionKO H1−/− [68]
Object recognitionKO H2−/− [68]
Barnes mazeKO H1−/− [68]
Barnes mazeKO H2−/− [68]
Barnes mazeKO H3−/− [118]
Motoric long-term memoryKO H1−/− [119]
Episodic and procedural memoryKO H1−/− [119]

*This work was done using female mice.
Hdc: histidine decarboxylase.
H1, H2, H3: histaminergic receptor type.