RAMH: (R)-(−)-alpha-methylhistamine 1Effect reverted with concomitant administration of the H2 receptor antagonist ranitidine 2Effect reverted with concomitant administration of the H1 receptor antagonist pyrilamine 3Impairment induced using intrahippocampal injection of MK-801 4Impairment induced using intraseptal injection of muscimol 5Impairment induced using intrahippocampal injection of scopolamine.